Cancer risk among Danish women with cosmetic breast implants

The available epidemiologic evidence does not support a carcinogenic effect of silicone breast implants on breast or other cancers. Data on cancer risk other than breast cancer are limited and few studies have assessed cancer risk beyond 10-15 years after breast implantation. We extended follow-up of our earlier cohort study of Danish women with cosmetic breast implants by 7 years, yielding 30 years of follow-up for women with longest implant duration. The study population consisted of women who underwent cosmetic breast implant surgery at private clinics of plastic surgery (n = 1,653) or public hospitals (n = 1,110), and a control group of women who attended private clinics for other plastic surgery (n = 1,736), between 1973-95. Cancer incidence through 2002 was ascertained using the Danish Cancer Registry. Risk evaluation was based on computation of standardized incidence ratios (SIR) and Cox proportional hazards models, adjusting for age, calendar period and reproductive history. We observed 163 cancers among women with breast implants compared to 136.7 expected based on general population rates (SIR = 1.2; 95% confidence interval [CI] = 1.0-1.4), during a mean follow-up period of 14.4 years (range = 0-30 years). Women with breast implants experienced a reduced risk of breast cancer (SIR = 0.7; 95% CI = 0.5-1.0), and an increased risk of non-melanoma skin cancer (SIR = 2.1; 95% CI = 1.5-2.7). Stratification by age at implantation, calendar year at implantation and time since implantation showed no clear trends, however, the statistical precision was limited in these analyses. When excluding non-melanoma skin cancer, the SIR for cancer overall was 1.0 (95% CI = 0.8-1.2). With respect to other site-specific cancers, no significantly increased or decreased SIR were observed. Similar results were found when directly comparing women who had implants at private clinics with women who attended private clinics for other plastic surgery, with rate ratios for cancer overall, breast cancer and non-melanoma skin cancer of 1.1 (95% CI = 0.8-1.6), 0.7 (95% CI = 0.4-1.3) and 1.5 (95% CI = 0.8-2.7), respectively. In conclusion, our study lends further support to the accumulating evidence that silicone breast implants are not carcinogenic. Reasons for the consistently reported deficit of breast cancer among women with breast implants remain unclear, whereas increased exposure to sunlight may explain the excess occurrence of non-melanoma skin cancer. We found no indication of delayed diagnosis of breast cancer due to the presence of breast implants.     

Cancer incidence in a cohort of Ontario and Quebec women having bilateral breast augmentation

The possibility that women, who receive breast implants for cosmetic purposes, have increased long-term risks of developing cancer continues to be debated. The objective of our study was to prospectively examine cancer incidence among women who received breast implants. A cohort was assembled of 24,558 women, 18 years of age and older, who underwent bilateral cosmetic breast augmentation, and 15,893 women who underwent other cosmetic procedures in Ontario or Quebec between 1974 and 1989. These plastic surgery patients were selected from the same clinics as the implant population. Incident cancers were identified by linking to Canadian registry data up to December 31, 1997. In total, 676 cancers were identified among women who received breast implants compared to 899 expected based on general population rates (standardized incidence ratio (SIR) = 0.75; 95% confidence interval (CI) = 0.70-0.81). Overall cancer incidence rates among women who received breast implants were similar to that of the other plastic surgery patients (relative risk (RR) = 0.91, 95% CI = 0.81-1.02). However, women who received breast implants had lower breast cancer rates than the plastic surgery patients (RR = 0.64, 95% CI = 0.53-0.79). No increased risks were observed among the implant population for any of the other cancer sites examined. Comparisons involving only women who received breast implants found no association between long-term breast cancer incidence and implant site (submuscular vs. subglandular), fill (saline vs. silicone) or envelope (polyurethane-coated or not). In conclusion, women undergoing cosmetic breast augmentation do not appear to be at an increased long-term risk of developing cancer.     

Cancer occurrence after cosmetic breast implantation in Denmark

Most studies on cancer incidence after breast implantation have focused on breast cancer, while the risk of cancers at other sites has been less well investigated. We examined cancer incidence among 1,653 women who underwent cosmetic breast implant surgery at private clinics of plastic surgery in Denmark and 1,736 women attending the same clinics for other reasons during the period 1973-1995. Furthermore, we updated previously reported results among 1,114 women who received implants for cosmetic indications at public hospitals. All women were followed for cancer through the Danish Cancer Registry. In comparison with the general female population, the overall standardized incidence ratio (SIR) for cancer among women who received implants in private clinics was 1.65 [95% confidence interval (CI) = 1.17-2.27]. This elevated SIR reflected increased incidence ratios for almost all major cancer sites; however, only for non-melanoma skin cancer was there an excess of more than 2 cases. No significant excess of cancer was observed among women who received implants in public hospitals (SIR = 1.10, 95% CI = 0.76-1.52) or among women attending the private clinics for other problems (SIR = 1.10, 95% CI = 0.78-1.52). The SIRs for breast cancer after breast implantation were 1.1 (95% CI = 0.5-2.2) among private clinic patients and 0.9 (95% CI = 0.4-1.7) among public hospital patients. The overall findings of these 2 implant cohorts and results from other investigations suggest that cancer risk is probably not increased among women receiving cosmetic breast implants. The inconsistent results for private clinics and public hospitals are likely related to selection bias and confounding among the private clinic patients, but our data did not permit exploration of these possibilities. Further research into the determinants of these inconsistencies is warranted.     

Breast implants and cancer risk in Denmark

Although millions of women worldwide have received breast implants for cosmetic or medical reasons, possible late effects (in particular cancer) have not been well studied. To provide quantitative information on cancer occurrence among women undergoing breast implant surgery, 1,135 women treated for cosmetic reasons in Denmark were evaluated. Patients were identified using the nationwide Hospital Discharge Registry with linkage to the nationwide Danish Cancer Registry to determine subsequent cancer incidence. The average age of the women at implant surgery was 31 years, and the average follow-up was 8.4 years, up to a maximum of 17 years. Overall, 27 cancers developed after implant surgery compared with 24.7 expected based on incidence rates from the general population (standardized incidence ratio [SIR]= 1.1; 95% CI: 0.7-1.6). Eight breast cancers were observed vs. 7.8 expected (SIR = 1.0; 95% CI: 0.4-2.0). No evidence was found to link breast implants with increased cancer risk in the decade after surgery. While the results are encouraging, longer follow-up into later life will be necessary to assess fully any possible adverse effects. Int. J. Cancer 71: 956-958, 1997. © 1997 Wiley-Liss Inc.     

The influence of cosmetic breast augmentation on the stage distribution and prognosis of women subsequently diagnosed with breast cancer

This study aimed to determine whether cosmetic breast implants impair the early detection of breast cancer, and adversely influence survival. This analysis derives from a cohort of 24,558 women who received bilateral cosmetic breast implants, and 15,893 women who underwent other plastic surgery procedures at the same practices in Ontario and Quebec, Canada, between 1974 and 1989. Incident cancers and vital status through 1997 were determined by record linkage to the Canadian Cancer Registry and Canadian Mortality Database. Analyses are based on a total of 182 and 202 incident cases of breast cancer identified among the implant and control groups, respectively. Contingency table analyses were performed to test for differences in the stage distribution of breast cancers between the 2 groups. Potential differences in survival were evaluated using the Kaplan–Meier estimates and Cox proportional hazards models. Women who received breast implants were more likely to have advanced stage breast carcinoma relative to the other plastic surgery patients (crude and adjusted ps ≤ 0.01). No statistically significant differences in distributions between the implant and control patients were found for age at diagnosis, tumor size, histological type, period of diagnosis or length of follow‐up. The delayed diagnosis in augmented women did not appear to influence the overall prognosis. Breast cancer‐specific survival was similar in both groups (hazard ratio = 1.06; 95% confidence interval = 0.65–1.74). In conclusion, this study suggests that breast implants delay the detection of breast cancer, but there was no statistically significant difference in survival between the breast implant and other plastic surgery groups.     

Canadian breast implant cohort: extended follow-up of cancer incidence

Cosmetic breast implants are not associated with increased breast cancer incidence, but variations of risk according to implant characteristics are still poorly understood. As well, the assessment of cancer risk for sites other than breast needs to be clarified. The purpose of this study was to fill these research gaps. This study presents an extended analysis of 10 more years of follow-up of a large Canadian cohort of women who received either cosmetic breast implants (n = 24,558) or other cosmetic surgery (15,893). Over 70% of the implant cohort was followed for over 20 years. Cancer incidence among implant women was compared to those of controls using multivariate Poisson models and the general female population using the standardized incidence ratios (SIRs). Women with breast implants had reduced rates of breast and endometrial cancers compared to other surgery women. Subglandular implants were associated to a reduced rate of breast cancer compared to submuscular implants [incidence rate ratio (IRR) = 0.78, 95% confidence interval (CI) = 0.63-0.96] and this reduction persisted over time. We observed a sevenfold increased rate (IRR = 7.36, 95% CI = 1.86-29.12) of breast cancer in the first 5 years after the date of surgery for polyurethane-coated subglandular implant women but this IRR decreased progressively over time (p value for trend = 0.02). We also observed no increased risk of rarer forms of cancer among augmented women. A reduction in breast cancer incidence was observed for women with subglandular implants relative to women with submuscular implants. Possible increase of breast cancer incidence shortly after breast augmentation with polyurethane implants needs to be verified.     

Risk of breast cancer in female flight attendants: a population-based study (Iceland)

Objectives: To study whether increased cancer risk, particularly of cancer types previously related to radiation, was found among cabin attendants, using employment time as a surrogate of exposure to cosmic radiation. Methods: A cohort of 1690 cabin attendants, 158 men and 1532 women from the Icelandic Cabin Crew Association and two airline companies in Iceland, was established. Cancer sites were ascertained between 1955 and 1997 by follow-up in a cancer registry. The personal identification number of each subject was used in record linkage to population-based registers containing vital and emigration status, reproductive factors and histologically verified cancer diagnosis. Standardized incidence rates (SIR) of different cancer sites in relation to employment time and year of hiring were calculated, as well as predictive values of breast cancer risk for evaluating possible confounding due to reproductive factors. Results: The total number of person-years was 27,148. Among the women, 64 cancers were observed whereas 51.63 were expected (SIR 1.2, 95% CI 1.0–1.6), and significantly increased risk for malignant melanoma (SIR 3.0, 95% CI 1.2–6.2) was found. Significantly increased risks of overall cancers (SIR 1.3, 95% CI 1.0–1.8) and breast cancer (SIR 1.6, 95% CI 1.0–2.4) were observed among the female cabin attendants when 15 years lag time was applied. Those hired in 1971 or later had the heaviest exposure to cosmic radiation at a young age and had significantly increased risk of overall cancer (SIR 2.8, 95% CI 1.4–4.9) and breast cancer (SIR 4.1, 95% CI 1.7–8.5). Predictive values calculated on the basis of reproductive factors among the cabin attendants and the population, and risk of breast cancer were 1.0 for parous vs. nulliparous, 1.0 for number of children, and 1.1 for age at birth of first child. Conclusion: The increased risk of breast cancer and malignant melanoma among cabin attendants seems to be occupationally related. The part played by occupational exposures, i.e. cosmic radiation, disturbance of the circadian rhythm, and electromagnetic fields or combination of these factors in the etiology of breast cancer among the cabin crew, is still a puzzle as confounding due to parity appears to be ruled out. The relationship between the sunbathing habits of the cabin crew and the increased risk of malignant melanoma needs to be clarified. There is also an urgent need to elucidate the importance of these findings for today's aviation.     

Risk of cancer in BRCA1 and BRCA2 mutation-positive and -negative breast cancer families (Finland)

Objectives: To compare the risk of cancer between BRCA1 or BRCA2 mutation-positive and -negative families. Methods: We assessed standardized incidence ratios (SIR) in 107 Finnish breast cancer families (12 BRCA1, 11 BRCA2, 84 non-BRCA1/2) with confirmed genealogy. The observed numbers of cancer cases were compared to the expected ones; both numbers were based on the population-based Finnish Cancer Registry. Results: Risk of ovarian cancer for first-degree relatives was high in BRCA1 (SIR 29, 95% confidence interval 9.4–68) and in BRCA2 families (SIR 18, 8.3–35), but not increased for non-BRCA1/2 families (SIR 1.0, 0.2–2.9). The SIR for subsequent ovarian cancer among breast cancer patients was 61 (20–142), 38 (11–98), and 0 (0–4.2), respectively. The risk of subsequent new breast cancer among breast cancer patients was equally high in BRCA1 families (SIR 11, 3.6–26) and in BRCA2 families (SIR 10, 3.3–24) and somewhat lower in mutation-negative families (SIR 3.7, 2.1–6.1). The risk of breast cancer among relatives was markedly increased in all three groups. The only elevated SIR, besides breast and ovarian, was that for prostate cancer in BRCA2 families (SIR 4.9, 1.8–11). Conclusions: The excess risk of breast cancer in non-BRCA1/2 families suggests the existence of another predisposition gene which seems not to be linked with increased risk of ovarian cancer.     

Increased risk of second malignancies after in situ breast carcinoma in a population-based registry

Among 1276 primary breast carcinoma in situ (BCIS) patients diagnosed in 1972-2002 in the Southern Netherlands, 11% developed a second cancer. Breast carcinoma in situ patients exhibited a two-fold increased risk of second cancer (standardised incidence ratios (SIR): 2.1, 95% confidence interval (CI): 1.7-2.5). The risk was highest for a second breast cancer (SIR: 3.4, 95% CI: 2.6-4.3; AER: 66 patients per 10,000 per year) followed by skin cancer (SIR: 1.7, 95% CI: 1.1-2.6; AER: 17 patients per 10,000 per year). The increased risk of second breast cancer was similar for the ipsilateral (SIR: 1.9, 95% CI: 1.3-2.7) and contralateral (SIR: 2.0, 95% CI: 1.4-2.8) breast. Risk of second cancer was independent of age at diagnosis, type of initial therapy, histologic type of BCIS and period of diagnosis. Standardised incidence ratios of second cancer after BCIS (SIR: 2.3, 95% CI: 1.8-2.8) resembled that after invasive breast cancer (SIR: 2.2, 95% CI: 2.1-2.4). Surveillance should be directed towards second (ipsi- and contra-lateral) breast cancer.     

Cancer among Scandinavian women with cosmetic breast implants: A pooled long‐term follow‐up study

No increased risks of specific types of cancer following breast implantation have been consistently reported, but data on risk beyond 15 years are limited. We have pooled the results of 2 nationwide cohort studies of 3,486 Swedish and 2,736 Danish women who underwent cosmetic breast implantation between 1965 and 1993. Cancer incidence through 2002 was ascertained through nationwide cancer registries. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated to compare cancer incidence among women with implants with women in the general population. Mean duration of follow up was 16.6 years (range 0.1–37.8 years). Over 50% of women were followed for 15 years or more after breast implantation and 13.3% for at least 25 years. There was a reduced incidence of breast cancer (SIR = 0.73; 95% CI 0.58–0.90), whereas lung cancer was above expectation (SIR = 1.64; 95% CI 1.10–2.36). The increased risk of lung cancer is expected due to the high prevalence of smoking among the women with implants in our study. With respect to other site‐specific cancers, no significantly increased or decreased SIR was observed. This study, which includes women followed for almost 4 decades, represents the longest follow up of women with cosmetic breast implants to date. The results provide no evidence of an association between breast implants and any type of cancer. © 2008 Wiley‐Liss, Inc.     

Risk of breast cancer subsequent to histological or clinical diagnosis of fibroadenoma - retrospective longitudinal study of 3938 cases

Background: The widespread belief that fibroadenoma is associatedwith an increased risk of subsequent breast cancer is based on studies ofhistologically-confirmed fibroadenomas. In current practice only a minorityof fibroadenomas are excised; most of them are diagnosed on the basis ofpalpation and imaging, and are not surgically removed. The decision forsurgical excision may be influenced by the presence of individual riskfactors, and this can act as a confounder and bias studies that are based onlyon surgically excised fibrodenomas.Patients and methods: To investigate this hypothesis we linked datafrom a consecutive series of 3938 fibroadenomas diagnosed histologically (n= 1335) or clinically (n = 2603) in women aged 30 to 69 years to theTuscany Cancer Registry database. After exclusion of concurrent breast cancersor cancers occurring within six months after the diagnosis of fibroadenoma,the observed and expected incidence of subsequent breast cancer were compared.Results: The overall Standardized Incidence Ratio (SIR) for excisedand non-excised fibroadenomas was 1.38 (95% CI = 1.1–1.7). TheSIR for histologically-confirmed fibroadenomas was 2.0 (95% CI1.4–2.7) whereas there was no apparent risk for non-excisedfibroadenomas (SIR = 0.97, 95% CI = 0.7–1.4).Conclusion: This study suggests that assessment of breast cancer risksubsequent to a diagnosis of fibroadenoma may be biased if the analysis islimited to surgically-excised fibroadenomas.     

A cohort study of reproductive factors and family history of breast cancer in southern Sweden

Background. Studies have been contradictory regarding the hypothesis that reproductive risk factors of breast cancer as parity and age at first full-term pregnancy (AFFP) operate differently in women with and without a family history of breast cancer. Methods. The overall tumour incidence and breast cancer incidence related to fertility factors were followed in a population based cohort of 29,508 women aged 25–65 when interviewed between 1990 and 1992 in south Sweden. At the end of the follow up in December 1999, the cohort constituted 226,611 person years. The risk of breast cancer in relation to reproductive factors were studied in women with at least one first degree relative with breast cancer and compared with women without a family history. Findings. A total of 1145 malignant tumours were seen and 1166.6 were expected (SIR = 0.98, 95% CI = 0.93–1.04). Slightly more breast cancer cases were seen 434 than expected 387.69 (SIR = 1.12, 95% CI = 1.02–1.23). A family history of breast cancer among a first degree relative was present in 1615 women. Forty-five breast cancers were seen among these women while 24.27 was expectecd (SIR = 1.85, 95% CI = 1.35–2.48). Nulliparous women with a family history of breast cancer had a higher risk of breast cancer, SIR = 1.76, 95% CI = 0.64–3.82, compared with nulliparous women without a family history, SIR = 1.13, 95% CI 0.99–1.29. Similarly women with parity 1–2 with a family history had a higher SIR = 1.81, 95% CI = 1.16–2.69 compared with women without a family history having 1–2 children, SIR = 1.13, 95% CI = 0.99–1.29. In women with 3 children those with a family history continued to have a high SIR = 1.98, 95% CI = 1.11–3.27 compared with women without a family history SIR = 0.90, 95% CI = 0.73–1.09. An early full-term pregnancy was protective in both groups. A higher risk than nulliparous women were seen after age 25 in the family history group and after age 30 in the sporadic cancer group. Interpretation. Women with a first degree family history of breast cancer do not experience the same protection from a high number of pregnancies as women without a family history. However, an early first full-term pregnancy seems to offer a substantial protection in the family history group if undertaken before age 20. This suggest that reproductive factors tend to operate differently in the two groups of women.     

Incidence of cancer among patients with knee implants in Sweden, 1980-1994

BACKGROUND: As knee implants become more common, it is important to study their potential health risks. We investigated cancer occurrence in a nationwide population-based cohort of 30,011 patients who underwent knee replacement surgery in Sweden from 1980 to 1994. METHODS: Patients were followed from 1 year after the date of their surgery through December 31, 1995, accruing 122,616 person-years of observation. The average follow-up time was 4.3 years, with 2365 patients followed for 10 years or more. RESULTS: Overall cancer incidence was not elevated compared with the general population of Sweden (standardized incidence ratio [SIR] = 1.03; 95% confidence interval [CI] = 0.98-1.08). A reduced rate for all respiratory cancers (SIR = 0.73; 95% CI = 0.59-0.91) and for lung cancer (SIR = 0.73; 95% CI = 0.58-0.91) was found among both men and women. Elevated rates were found for prostate (SIR = 1.20; 95% CI = 1.06-1.34) and bone cancer (SIR = 6.00; 95% CI = 1.24-17.52) in men. The bone cancer excess was based on three observed cases, two of which occurred at a site unrelated to the implant and the site of the third tumor is unknown. Rates of connective tissue cancer and leukemia-lymphoma were not elevated significantly among knee implant recipients. Long-term follow-up (>or= 10 years) did not show a significant excess risk for all cancer (SIR = 1.10; 95% CI = 0.86-1.38) or for any site-specific cancer, including bone cancer, lymphoma, or leukemia. Subgroup analyses for patients with rheumatoid arthritis produced results similar to the overall results. CONCLUSIONS: This epidemiologic study of cancer risk among patients with knee implants is the largest to date. It provides evidence that the incidence of cancer among patients with knee implants is similar to that of the general population. Continued follow-up of this cohort is warranted to evaluate further potential long-term effects of these implants.     

Cancer incidence among marine engineers,a population-based study (Iceland)

Objectives: Marine engineers are in their occupation exposed to different chemicals, organic solvents, exhaust gases, oils, and petroleum products, and were formerly exposed to asbestos. The aim was to study the cancer pattern, with particular attention to lung and bladder cancer, in an Icelandic cohort of marine engineers, indirectly controlling for their smoking habits. Methods: A cohort of 6603 male marine engineers was followed up from 1955 to 1998, a total of 167,715 person-years. The cohort was record linked by the engineers' personal identification numbers to population-based registers containing the vital and emigration status and cancer diagnosis. Standardized incidence ratios (SIRs) were calculated for all cancers and different cancer sites in relation to different lag time and year of graduation. Information on smoking habits was obtained by administering a questionnaire to a sample of the cohort (n = 1501). Results: In the total cohort 810 cancers were observed, whereas 794 were expected (SIR 1.0, 95% CI 1.0–1.1), and significantly increased risk of stomach cancer (SIR 1.3, 95% CI 1.0–1.5) and lung cancer (SIR 1.2, 95% CI 1.0–1.5) was found. Increased risk of all cancers (SIR 1.2, 95% CI 1.1–1.3), stomach cancer (SIR 1.5, 95% CI 1.1–1.9), lung cancer (SIR 1.4, 95% CI 1.2–1.8), pleural mesothelioma (SIR 4.8, 95% CI 1.3–12.3), and urinary bladder cancer (SIR 1.3, 95% CI 1.0–1.8) were observed when a 40-year lag time was applied. The engineers' smoking habits were similar to those in a sample of the general population. The predictive value for lung cancer was 1.03. Conclusions: The increased risk for mesothelioma is possibly attributable to the previous asbestos exposure. The excess of lung cancer could also be related to asbestos exposure. The high incidence of stomach cancer, lung cancer, and bladder cancer may be related to exposure to chemical risk factors, such as oils and petroleum products, as confounding due to smoking seems to be ruled out. In the light of the limited exposure information in the present study the importance of the different occupational exposures needs to be evaluated in further studies.     

Family history and risk of breast cancer in hispanic and non-hispanic women: the New Mexico Women's Health Study

Objectives: Many epidemiologic studies have demonstrated that an increased risk of breast cancer is associated with positive family history of this disease. Little information had been available on the relationship of breast cancer risk with family history in Hispanic women. To investigate the association of family history of breast cancer on the risk of breast cancer, we examined the data from the New Mexico Women's Health Study (NMWHS), a statewide case–control study. Methods: In this study 712 women (332 Hispanics and 380 non-Hispanic whites) with breast cancer and 844 controls (388 Hispanics and 456 non-Hispanic whites) were included. Conditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (95% CI), adjusted for sociodemographic, medical, and reproductive factors. Results: We found an increased risk in women with a history of breast cancer in one or more first-degree or second-degree relatives (OR = 1.5, 95% CI 1.2–1.9), first-degree relatives (OR = 1.3, 95% CI 1.0–1.8) and second-degree relatives (OR = 1.6, 95% CI 1.2–2.2). Hispanic women had higher risk estimates for a positive family history (OR = 1.7, 95% CI 1.1–2.5) than non-Hispanic white women (OR = 1.4, 95% CI 1.0–2.0); however, the differences were not statistically significant. In both ethnic groups a higher risk was observed in premenopausal women compared with postmenopausal women and women diagnosed with breast cancer before age 50years compared with older women. Conclusions: The results indicate that Hispanic women with a family history of breast cancer are at increased risk of breast cancer.     

Bone Mineral Density and Endogenous Hormones and Risk of Breast Cancer in Postmenopausal Women (United States)

Objective: This case–cohort study was designed to examine whether total hip bone mineral density (BMD) is independently associated with breast cancer over and above its association with other determinants, including levels of total and bioavailable estradiol and testosterone and sex-hormone binding globulin. Methods: Our study population was selected from a cohort of 8203 postmenopausal women who were screened for the Fracture Intervention Trial in 1992, at which time BMD was assessed, and blood samples were obtained. A total of 109 women developed breast cancer during four years of follow-up; 173 other randomly selected women from the larger cohort were also selected. Cox proportional hazards with robust variance adjustment was used for these analyses. Results: Relative to women in the lower fourth of the BMD distribution, the risk associated with being in the upper fourth was 2.6 (95% confidence interval (CI) 1.1–5.8). After adjusting for serum hormone levels, the corresponding relative risk was 2.5 (95% CI 0.9–5.2). With body mass index and number of years since menopause added to the multivariate analysis, the relative risk decreased to 1.4 (95% CI 0.5–4.0).Conclusions: BMD may not influence breast cancer risk independent of its relationship with endogenous hormones and measured covariates.     

Risk factors for local recurrence after conservative treatment in stage I breast cancer. Definition of a subgroup not requiring radiotherapy

Background: Risk factors for local recurrence after breast-conservingtreatment of early breast cancer have not previously been evaluated insettings where mammography has been a major pathway to diagnosis of bothprimary tumour and recurrences, or in patients treated surgically by a formalsector resection.Patients and methods: Three hundred eighty-one women with stage Iprimary breast cancer were randomised after a standardised sector resectionto either a course of postoperative radiotherapy to 54 Gy to the breast (XRTgroup) or to surgery alone (non XRT group). At five years, 43 localrecurrences, six of them in the XRT group, appeared. Patient characteristicscollected from the medical records, histopathological characteristicsdetermined by re-examination of slides, and mammographic characteristcs fromthe pre-operative mammograms were evaluated as risk factors for recurrence byunivariate and multivariate Cox proportional hazards models. Results arereported as relative hazards (RH) with 95% confidence intervals(95% CI).Results: In the univariate analysis comedo cancer, RH 3.5 (95%CI 1.8–6.7), lobular cancers RH 2.8 (95% CI 1.1–7.1),mammographic appearance as circular/oval shaped density, RH 2.3 (95%CI 1.1–4.5), and mammographic appearance as a stellate lesion withmicrocalcifications inside the lesion, RH 3.8 (95% CI 1.1–13.0)were identified as risk factors for local recurrence. Age, with a RH of 0.97(95% CI 0.94–0.99) for each increasing year was inverselyassociated with risk. A multivariate analysis, which also took postoperativeradiotherapy into account, only showed comedo cancers with a RH 2.6(95% CI 1.3–5.0) and mammographic appearance of a stellate lesionwith microcalcification inside the lesion RH 4.5 (95% CI1.1–17.6) to be statistically significant. The estimates for age RH 0.98(95% CI 0.95–1.0) and lobular cancers RH 2.5 (95% CI0.98–6.6) were marginally changed, with widened CIs. Patients > 60years of age, without comedo or lobular carcinomas were found to be at lowrisk (5.9% at five years in Kaplan–Meyer estimate) of localrecurrence, even without postoperative radiotherapy.Conclusion: Low age, comedo and lobular cancers and mammographicappearance of the tumour as a stellate lesion with microcalcifications insidethe lesion indicate an increased risk for local recurrence after sectorresection in stage I tumours at five years. Patients >60 years of agewithout comedo or lobular cancers are at low risk for local recurrence at fiveyears even without postoperative radiotherapy.     

Increased risk of early-stage breast cancer related to consumption of sweet foods among women less than age 45 in the United States

Objectives: To evaluate the associations of dietary macronutrients, food groups, and eating patterns with risk of breast cancer in a population-based case–control study. Methods: In this study among women 20–44 years of age, 568 cases with breast cancer and 1451 population-based controls were included. They completed a detailed in-person interview, a self-administered food-frequency questionnaire and were measured for anthropometric indices. Logistic regression was used to estimate odds ratios (OR) and their 95% confidence intervals (CI) of breast cancer, adjusted for age, study site, race, education, alcohol consumption, oral contraceptive usage, smoking status, and body mass index. Results: There was no association between breast cancer risk and intake of calories, macronutrients, or types of fat. Risk of breast cancer was unrelated to intakes of a variety of food groups, including red meats, dairy, high-fat snacks and desserts, or foods high in animal fat. Increased risk was observed for high intake of a food group composed of sweet items, particularly sodas and desserts. Risk increased linearly with percent of calories from sweets and frequency of sweets intake. Consumption of sweets 9.8 or more times per week compared with <2.8 times per week was associated with an adjusted OR of 1.32 (95% CI = 1.0–1.8). This association did not appear to be due to the high-fat foods or carbonated beverages that comprised the food group. Compared with women reporting one or two meals and snacks per day, reduced risks were noted for women reporting six or more (OR = 0.69, 95% CI = 0.4–1.1). Conclusions: These data suggest a modest relationship between intakes of sweet items with risk of in-situ and localized breast cancer in young women. This relation is consistent with the hypothesized link of high insulin exposure and risk of breast cancer. There was some suggestion that women who ate many times during the day were at reduced risk of disease, which is also consistent with an insulin-related mechanism.     

Breastfeeding and breast cancer risk by age 50 among women in Germany

Background: Epidemiological evidence which suggests that prolonged breastfeeding protects against breast cancer has accumulated in recent years. Issues with regard to the timing of breastfeeding and effect modification by correlates of breastfeeding and other risk factors of breast cancer remain unresolved. Methods: A population-based case–control family study of breast cancer among women diagnosed by the age of 50, conducted in two geographic areas in Germany, was used to evaluate the effect of breastfeeding on risk of breast cancer. Results: Among parous women in this study (553 cases, 1094 age-matched population controls), having ever breastfed a child for at least 1 month did not confer protection (odds ratio of 0.9 and 95% confidence interval (CI) 0.8–1.2). However, risk of breast cancer significantly decreased with increasing duration of breastfeeding (p for trend = 0.01) and the estimated relative risk was 0.6 (95% CI 0.4–0.9) for 13–24 months of cumulative breastfeeding and 0.5 (95% CI 0.3–1.1) for 25 months or more. Risk was less related to number of children breastfed than to increasing average length of breastfeeding per child (p for trend = 0.03). Conclusions: The reduction in risk associated with duration of breastfeeding was not primarily due to breastfeeding the firstborn and more evident in women who were older ( > 25 years) when they first breastfed and among women who experienced a recent full-term pregnancy. Risks were modified somewhat by a first-degree family history of breast cancer whereby a greater reduction in risk per additional month of breastfeeding was observed among women with a family history than those without (0.9 vs. 1.0). The study results support a protective role of prolonged breastfeeding against the development of breast cancer in predominantly premenopausal women in Germany.     

Metabolic disorders and breast cancer risk (United States)

Objective: To clarify the hormonal context of breast cancer etiology we used data from a large, population-based case–control study to investigate the relationship between breast cancer risk and a history of diabetes mellitus, disorders associated with estrogen stimulation (uterine fibroids, endometriosis, gallstones), and disorders associated with androgen stimulation (acne, hirsutism, and polycystic ovaries). Methods: Breast cancer patients between 50 and 75 years old were identified from state-wide tumor registries in Wisconsin, Massachusetts, and New Hampshire; controls were randomly selected from drivers' license lists (age less than 65) or Medicare enrollment files (age 65–74). Information on reproductive history, medical history, and personal habits was obtained by telephone interview. A total of 5659 cases and 5928 controls were interviewed and provided suitable data. Results: There was no overall association between breast cancer risk and reported history of diabetes mellitus, endometriosis, uterine fibroids, gallstones, or cholecystectomy. However, the disorders with androgenic associations all conferred an increased risk: the overall odds ratio (OR) for a history of acne was 1.4 (95% CI 1.0–1.9), that for hirsutism was 1.2 (95% CI 0.81–1.8), and that for polycystic ovaries 1.6 (95% CI 0.8–3.2). Diabetes mellitus diagnosed before age 35 conferred an odds ratio of 0.52 (95% 0.25–1.1), while diabetes diagnosed at a later age was associated with an increased risk (OR = 1.2, 95% CI 1.0–1.4). Conclusions: Androgen-related phenomena are likely to be important in the etiology of breast cancer.