Tubal ligation in relation to menopausal symptoms and breast cancer risk

Background:

Local inflammation after tubal ligation may affect ovarian function and breast cancer risk.

Methods:

We analysed tubal ligation, menopausal characteristics, and breast cancer risk in the Sister Study cohort (N=50 884 women).

Results:

Tubal ligation was associated with hot flashes (hazard ratio (HR) 1.09; 95% confidence interval (CI): 1.06–1.12) but not menopausal age (HR 0.99; 95% CI: 0.96–1.02). Tubal ligation did not have an impact on breast cancer overall (HR 0.95; 95% CI: 0.85–1.06), but had a suggested inverse relation with oestrogen receptor+/progesterone receptor+ invasive tumours (HR 0.84; 95% CI: 0.70–1.01), possibly because of subsequent hysterectomy/bilateral oophorectomy.

Conclusion:

Tubal ligation does not influence overall breast cancer risk.     

Weight change in adulthood and risk of postmenopausal breast cancer: the HUNT study of Norway

Background:

Adult weight gain is associated with increased risk of postmenopausal breast cancer. Most previous studies are limited by using recalled or self-reported data, and it is not known if age-specific weight changes are important for breast cancer risk.

Methods:

In a Norwegian cohort of 28 153 women (and 900 incident breast cancers) with longitudinal anthropometric measurements over up to 30 years, we studied both overall and age-related weight changes in adulthood and risk of postmenopausal breast cancer.

Results:

Overall, weight gain in adulthood was associated with increased breast cancer risk (hazard ratio (HR) per kg per year 1.31, 95% confidence interval (CI) 1.11–1.54). Weight gain before (HR per kg per year 1.38, 95% CI 1.09–1.75) or around menopause (1.69, 95% CI 1.32–2.16) was associated with increased risk, but there was no clear risk increase associated with later weight gain (HR per kg per year 0.92, 95% CI 0.73–1.18).

Conclusion:

Weight gain in adulthood was associated with increased risk of breast cancer. Our results suggest that weight gain before and around menopausal age may be particularly important for breast cancer risk among postmenopausal women.     

Association of tamoxifen use and increased diabetes among Asian women diagnosed with breast cancer

Background:

We conducted a population-based cohort study to assess whether tamoxifen treatment is associated with an increased incidence of diabetes.

Methods:

Data obtained from the Taiwanese National Health Insurance Research Database were used for a population-based cohort study. The study cohort included 22 257 breast cancer patients diagnosed between 1 January 2000 and 31 December 2004. Among them, 15 210 cases received tamoxifen treatment and 7047 did not. Four subjects without breast cancer were frequency-matched by age and index year as the control group. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using multivariate Cox proportional hazards regression analysis.

Results:

Breast cancer patients exhibited a 14% higher rate of developing diabetes (adjusted HR=1.14, 95% CI=1.08–1.20) compared with non-breast cancer controls, but the significant difference was limited to tamoxifen users. In addition, tamoxifen users exhibited a significantly increased risk of diabetes compared with non-tamoxifen users among women diagnosed with breast cancer (adjusted HR=1.31, 95% CI=1.19–1.45). Stratification by age groups indicated that both younger and older women diagnosed with breast cancer exhibited a significantly higher risk of diabetes than the normal control subjects did, and tamoxifen users consistently exhibited a significantly higher diabetes risk than non-tamoxifen users or normal control subjects did, regardless of age. Both recent and remote uses of tamoxifen were associated with an increased likelihood of diabetes.

Conclusions:

The results of this population-based cohort study suggested that tamoxifen use in breast cancer patients might increase subsequent diabetes risk. The underlying mechanism remains unclear and further larger studies are mandatory to validate our findings.     

Background risk of breast cancer influences the association between alcohol consumption and mammographic density

Background:

Alcohol consumption has been suggested to increase risk of breast cancer through a mechanism that also increases mammographic density. Whether the association between alcohol consumption and mammographic density is modified by background breast cancer risk has, however, not been studied.

Methods:

We conducted a population-based cross-sectional study of 53 060 Swedish women aged 40–74 years. Alcohol consumption was assessed using a web-based self-administered questionnaire. Mammographic density was measured using the fully-automated volumetric Volpara method. The Tyrer–Cuzick prediction model was used to estimate risk of developing breast cancer in the next 10 years. Linear regression models were used to evaluate the association between alcohol consumption and volumetric mammographic density and the potential influence of Tyrer–Cuzick breast cancer risk.

Results:

Overall, increasing alcohol consumption was associated with higher absolute dense volume (cm³) and per cent dense volume (%). The association between alcohol consumption and absolute dense volume was most pronounced among women with the highest (⩾5%) Tyrer–Cuzick 10-year risk. Among high-risk women, women consuming 5.0–9.9, 10.0–19.9, 20.0–29.9, and 30.0–40.0 g of alcohol per day had 2.6 cm³ (95% confidence interval (CI), 0.2–4.9), 2.9 cm³ (95% CI, −0.6 to 6.3), 4.6 cm³ (95% CI, 1.5–7.7), and 10.8 cm³ (95% CI, 4.8–17.0) higher absolute dense volume, respectively, as compared with women abstaining from alcohol. A trend of increasing alcohol consumption and higher absolute dense volume was seen in women at low (⩽3%) risk, but not in women at moderate (3.0–4.9%) risk.

Conclusion:

Alcohol consumption may increase breast cancer risk through increasing mammographic density, particularly in women at high background risk of breast cancer.     

Pre-existing diabetes and breast cancer prognosis among elderly women

Background:

The objective of this study was to assess the impact of pre-existing diabetes on breast cancer prognosis.

Methods:

Women (n=2833) with centrally confirmed invasive breast cancer in the Women''s Health Initiative, who were linked to Medicare claims data (CMS) were followed from the date of breast cancer diagnosis to date of death or 20 September 2013. Information on diabetes was identified through the CMS Chronic Condition Warehouse algorithm. Cox proportional hazard regression was used to estimate adjusted hazard ratios for overall mortality. A competing risks model (proportional subdistribution) model was used to estimate hazard ratios for breast cancer-specific mortality.

Results:

Women with diabetes were more likely to have factors related to delayed diagnosis (less recent mammograms, and more advanced cancer stage) and were less likely to receive radiation therapy. Compared with women without diabetes, women with diabetes had significantly increased risk of overall mortality (HR=1.57, 95% CI: 1.23–2.01) and had nonsignificantly increased risk for breast cancer-specific mortality (HR=1.36, 95% CI: 0.86–2.15) before adjustment for factors related to delayed diagnosis and treatment. Adjustment for these factors resulted in a little change in the association of diabetes with overall mortality risk, but further attenuated the point estimate for breast cancer-specific mortality.

Conclusions:

Our study provides additional evidence that pre-existing diabetes increases the risk of total mortality among women with breast cancer. Very large studies with data on breast cancer risk factors, screening and diagnostic delays, treatment choices, and the biological influence of diabetes on breast cancer will be needed to determine whether diabetes also increases the risk for breast cancer-specific mortality.     

Does alcohol increase breast cancer risk in African-American women? Findings from a case–control study

Background:

Alcohol is an important risk factor for breast cancer in Caucasian women, but the evidence in African-American (AA) women is limited and results are inconclusive.

Methods:

Associations between recent and lifetime drinking and breast cancer risk were evaluated in a large sample of AA women from a case–control study in New York and New Jersey. Multivariable logistic regression models provided odds ratios (ORs) and 95% confidence intervals (CIs).

Results:

There was no association between recent drinking and breast cancer risk, even when stratified by menopausal status or by hormone receptor status. A borderline decreased risk with increased lifetime consumption was found (OR=0.77; 95% CI: 0.58–1.03), which was stronger among women who drank when under 20 years of age (OR=0.65; 95% CI: 0.47–0.89), regardless of menopausal or hormone receptor status.

Conclusion:

Breast cancer risk associated with recent alcohol consumption was not apparent in AA women, while early age drinking seemed to decrease risk. This is the first investigation on recent and lifetime drinking in subgroups and drinking during different age periods in AA women. If findings are replicated, racial differences in biological pathways involving alcohol and its metabolites should be explored.     

A nested case–control study of adjuvant hormonal therapy persistence and compliance,and early breast cancer recurrence in women with stage I–III breast cancer

Background:

Non-persistence and non-compliance are common in women prescribed hormonal therapy for breast cancer, but little is known about their influence on recurrence.

Methods:

A nested case–control study of associations between hormonal therapy non-persistence and non-compliance and the risk of early recurrence in women with stage I–III breast cancer was undertaken. Cases, defined as women with a breast cancer recurrence within 4 years of hormonal therapy initiation, were matched to controls (1 : 5) by tumour stage and age. Conditional logistic regression was used to examine associations between early recurrence and hormonal therapy non-persistence and non-compliance.

Results:

Ninety-four women with breast cancer recurrence were matched to 458 controls. Women who were non-persistent (⩾180 days without hormonal therapy) had a significantly increased adjusted recurrence odds ratio (OR) of 2.88 (95%CI 1.11, 7.46) compared with persistent women. There was no significant association between low compliance (OR 1.30; 95% CI 0.74, 2.30) and breast cancer recurrence.

Conclusion:

Hormonal therapy non-persistence is associated with a significantly higher risk of early recurrence in women with stage I–III oestrogen receptor (ER)-positive breast cancer. This finding is consistent with results from randomized studies of hormonal therapy treatment duration and suggests that interventions to target modifiable risk factors for non-persistence are required.     

Association between diabetes,diabetes treatment and risk of developing endometrial cancer

Background:

A growing body of evidence suggests that diabetes is a risk factor for endometrial cancer incidence. However, most of these studies used case-control study designs and did not adjust for obesity, an established risk factor for endometrial cancer. In addition, few epidemiological studies have examined the association between diabetes treatment and endometrial cancer risk. The objective of this study was to assess the relationships among diabetes, diabetes treatment and endometrial cancer risk in postmenopausal women participating in the Women''s Health Initiative (WHI).

Methods:

A total of 88 107 postmenopausal women aged 50–79 years who were free of cancer and had no hysterectomy at baseline were followed until date of endometrial cancer diagnosis, death, hysterectomy or loss to follow-up, whichever came first. Endometrial cancers were confirmed by central medical record and pathology report review. Multivariate Cox proportional hazards regression models were used to estimate hazard ratios (HRs) (95% confidence interval (CI)) for diagnosis of diabetes and metformin treatment as risk factors for endometrial cancer.

Results:

Over a mean of 11 years of follow-up, 1241 endometrial cancers developed. In the primary analysis that focused on prevalent diabetes at enrolment, compared with women without diabetes, women with self-reported diabetes, and the subset of women with treated diabetes, had significantly higher risk of endometrial cancer without adjusting for BMI (HR=1.44, 95% CI: 1.13–1.85 for diabetes, HR=1.57, 95% CI: 1.19–2.07 for treated diabetes). However after adjusting for BMI, the associations between diabetes, diabetes treatment, diabetes duration and the risk of endometrial cancer became non-significant. Elevated risk was noted when considering combining diabetes diagnosed at baseline and during follow-up as time-dependent exposure (HR=1.31, 95% CI: 1.08–1.59) even after adjusting for BMI. No significant association was observed between metformin use and endometrial cancer risk.

Conclusions:

Our results suggest that the relationship observed in previous research between diabetes and endometrial cancer incidence may be largely confounded by body weight, although some modest independent elevated risk remains.     

The association of waiting times from diagnosis to surgery with survival in women with localised breast cancer in England

Background:

Survival from breast cancer in the United Kingdom is lower than in other developed countries. It is unclear to what extent waiting times for curative surgery affect survival.

Methods:

Using national databases for England (cancer registries, Hospital Episode Statistics and Office of National Statistics), we identified 53 689 women with localised breast cancer, aged ⩾15 years, diagnosed between 1996 and 2009, who had surgical resection with curative intent within 62 days of diagnosis. We used relative survival and excess risk modelling to determine associations between waiting times and 5-year survival.

Results:

The median diagnosis to curative surgery waiting time among breast cancer patients was 22 days (interquartile range (IQR): 15–30). Relative survival was similar among women waiting between 25 and 38 days (RS: 93.5% 95% CI: 92.8–94.2%), <25 days (RS: 93.0% 95% CI: 92.5–93.4%) and between 39 and 62 days (RS: 92.1% 95% CI: 90.8–93.4%). There was little evidence of an increase in excess mortality with longer waiting times (excess hazard ratio (EHR): 1.06; 95% CI: 0.88–1.27 comparing waiting times 39-62 with 25–38 days). Excess mortality was associated with age (EHR 65–74 vs 15–44 year olds: 1.23; 95% CI: 1.07–1.41) and deprivation (EHR most vs least deprived: 1.28; 95% CI: 1.09–1.49), but waiting times did not explain these differences.

Conclusion:

Within 62 days of diagnosis, decreasing waiting times from diagnosis to surgery had little impact on survival from localised breast cancer.     

Incidence of colorectal cancer in BRCA1 and BRCA2 mutation carriers: results from a follow-up study

Background:

The BRCA1 and BRCA2 genes confer increased susceptibility to breast and ovarian cancer and to a spectrum of other cancers. There is controversy regarding the risk of colorectal cancer conferred by germline mutations in these two genes.

Methods:

We followed 7015 women with a BRCA mutation for new cases of colorectal cancer. Incidence rates in carriers were compared with population-specific incidence rates, and standardised incidence ratios (SIRs) were estimated. The expected numbers of cancers were computed by multiplying person–years at risk by the appropriate age-, sex- and country-specific incidence rates from the five countries.

Results:

Twenty-one incident colorectal cancer cases were observed among all mutation carriers, compared with 23.6 cases expected. The SIR for BRCA1 carriers was 0.92 (95% confidence interval (CI), 0.54–1.40, P=0.7) and for BRCA2 carriers was 0.82 (95% CI, 0.30–1.81, P=0.7). The SIR for colon cancer was 3.81 (95% CI 1.77–7.23) for women below the age of 50 years (both genes combined) and was 0.60 (95% CI 0.33–1.00) for women aged 50 years and above.

Conclusion:

The risk of colorectal cancer is increased in female carriers of BRCA1 mutations below the age of 50 years but not in women with BRCA2 mutations or in older women.     

Anti-diabetic medications and risk of primary liver cancer in persons with type II diabetes

Background:

Type II diabetes increases liver cancer risk but the risk may be mitigated by anti-diabetic medications. However, choice of medications is correlated with diabetes duration and severity, leading to confounding by indication.

Methods:

To address this association, we conducted a nested case–control study among persons with type II diabetes in the Clinical Practice Research Datalink. Cases had primary liver cancer and controls were matched on age, sex, practice, calendar time, and number of years in the database. Exposure was classified by type and combination of anti-diabetic prescribed and compared to non-use. Odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated using conditional logistic regression.

Results:

In 305 cases of liver cancer and 1151 controls, there was no association between liver cancer and anti-diabetic medication use compared to non-use (OR=0.74 (95% CI=0.45–1.20) for metformin-only, 1.10 (95% CI=0.66–1.84) for other oral hypoglycaemic (OH)-only, 0.89 (95% CI=0.58–1.37) for metformin+other OH, 1.11 (95% CI=0.60–2.05) for metformin+insulin, 0.81 (95% CI=0.23–2.85) for other OH+insulin, and 0.72 (95% CI=0.18–2.84) for insulin-only). Stratification by duration of diabetes did not alter the results.

Conclusions:

Use of any anti-diabetic medications in patients with type II diabetes was not associated with liver cancer, though there was a suggestion of a small protective effect for metformin.     

Organic food consumption and the incidence of cancer in a large prospective study of women in the United Kingdom

Background:

Organically produced foods are less likely than conventionally produced foods to contain pesticide residues.

Methods:

We examined the hypothesis that eating organic food may reduce the risk of soft tissue sarcoma, breast cancer, non-Hodgkin lymphoma and other common cancers in a large prospective study of 623 080 middle-aged UK women. Women reported their consumption of organic food and were followed for cancer incidence over the next 9.3 years. Cox regression models were used to estimate adjusted relative risks for cancer incidence by the reported frequency of consumption of organic foods.

Results:

At baseline, 30%, 63% and 7% of women reported never, sometimes, or usually/always eating organic food, respectively. Consumption of organic food was not associated with a reduction in the incidence of all cancer (n=53 769 cases in total) (RR for usually/always vs never=1.03, 95% confidence interval (CI): 0.99–1.07), soft tissue sarcoma (RR=1.37, 95% CI: 0.82–2.27), or breast cancer (RR=1.09, 95% CI: 1.02–1.15), but was associated for non-Hodgkin lymphoma (RR=0.79, 95% CI: 0.65–0.96).

Conclusions:

In this large prospective study there was little or no decrease in the incidence of cancer associated with consumption of organic food, except possibly for non-Hodgkin lymphoma.     

Concordance of National Cancer Registration with self-reported breast,bowel and lung cancer in England and Wales: a prospective cohort study within the UK Collaborative Trial of Ovarian Cancer Screening

Background:

It has been suggested that lower UK cancer survival may be due to incomplete case ascertainment by cancer registries.

Methods:

We assessed concordance between self-reported breast, bowel and lung cancer and cancer registration (CR) for 1995–2007 in England and Wales in the UK Collaborative Trial of Ovarian Cancer Screening.

Results:

Concordance of breast cancer CR was higher (94.7%:95% CI: 94.1–95.3%) than for bowel (85.1%:95% CI: 82.1–87.8%) and lung (85.4%:95% CI: 76.3–92.0%). CR concordance was lower in breast cancer (94.5% vs 98.8%) survivors compared with deceased but the difference was small. No difference was found for bowel (85.3% vs 94.6%) or lung (87.1% vs 90.5%) cancer.

Conclusion:

Concordance of CR and self-reported cancer is high. Incomplete registration is unlikely to be a major cause of lower UK survival rates.     

Reproductive risk factors and oestrogen/progesterone receptor-negative breast cancer in the Breast Cancer Family Registry

Background:

Oestrogen receptor (ER)- and progesterone receptor (PR)-negative (ER−PR−) breast cancer is associated with poorer prognosis compared with other breast cancer subtypes. High parity has been associated with an increased risk of ER−PR− cancer, but emerging evidence suggests that breastfeeding may reduce this risk. Whether this potential breastfeeding benefit extends to women at high risk of breast cancer remains critical to understand for prevention.

Methods:

Using population-based ascertained cases (n=4011) and controls (2997) from the Breast Cancer Family Registry, we examined reproductive risk factors in relation to ER and PR status.

Results:

High parity (⩾3 live births) without breastfeeding was positively associated only with ER−PR− tumours (odds ratio (OR)=1.57, 95% confidence interval (CI), 1.10–2.24); there was no association with parity in women who breastfed (OR=0.93, 95% CI 0.71–1.22). Across all race/ethnicities, associations for ER−PR− cancer were higher among women who did not breastfeed than among women who did. Oral contraceptive (OC) use before 1975 was associated with an increased risk of ER−PR− cancer only (OR=1.32, 95% CI 1.04–1.67). For women who began OC use in 1975 or later there was no increased risk.

Conclusions:

Our findings support that there are modifiable factors for ER−PR− breast cancer and that breastfeeding in particular may mitigate the increased risk of ER−PR− cancers seen from multiparity.     

Hormone use and risk for lung cancer: a pooled analysis from the International Lung Cancer Consortium (ILCCO)

Background:

The association between oral contraceptive (OC) use, hormone replacement therapy (HRT) and lung cancer risk in women is still debated.

Methods:

We performed a pooled analysis of six case–control studies (1961 cases and 2609 controls) contributing to the International Lung Cancer Consortium. Potential associations were investigated with multivariable unconditional logistic regression and meta-analytic models. Multinomial logistic regressions were performed to investigate lung cancer risk across histologic types.

Results:

A reduced lung cancer risk was found for OC (odds ratio (OR)=0.81; 95% confidence interval (CI): 0.68–0.97) and HRT ever users (OR=0.77; 95% CI: 0.66–0.90). Both oestrogen only and oestrogen+progestin HRT were associated with decreased risk (OR=0.76; 95% CI: 0.61–0.94, and OR=0.66; 95% CI: 0.49–0.88, respectively). No dose-response relationship was observed with years of OC/HRT use. The greatest risk reduction was seen for squamous cell carcinoma (OR=0.53; 95% CI: 0.37–0.76) in OC users and in both adenocarcinoma (OR=0.79; 95% CI: 0.66–0.95) and small cell carcinoma (OR=0.37; 95% CI: 0.19–0.71) in HRT users. No interaction with smoking status or BMI was observed.

Conclusion:

Our findings suggest that exogenous hormones can play a protective role in lung cancer aetiology. However, given inconsistencies with epidemiological evidence from cohort studies, further and larger investigations are needed for a more comprehensive view of lung cancer development in women.     

Vitamin D intake,blood 25(OH)D levels,and breast cancer risk or mortality: a meta-analysis

Background:

Experimental studies suggest potential anti-carcinogenic properties of vitamin D against breast cancer risk, but the epidemiological evidence to date is inconsistent.

Methods:

We searched MEDLINE and EMBASE databases along with a hand search for eligible studies to examine the association between vitamin D status (based on diet and blood 25-hydroxyvitamin D (25(OH)D)) and breast cancer risk or mortality in a meta-analysis. A random-effect model was used to calculate a pooled adjusted relative risk (RR).

Results:

A total of 30 prospective studies (nested case-control or cohort) were included for breast cancer incidence (n=24 studies; 31 867 cases) or mortality (n=6 studies; 870 deaths) among 6092 breast cancer patients. The pooled RRs of breast cancer incidence for the highest vs the lowest vitamin D intake and blood 25(OH)D levels were 0.95 (95% CI: 0.88–1.01) and 0.92 (95% CI: 0.83–1.02), respectively. Among breast cancer patients, high blood 25(OH)D levels were significantly associated with lower breast cancer mortality (pooled RR=0.58, 95% CI: 0.40–0.85) and overall mortality (pooled RR=0.61, 95% CI: 0.48–0.79). There was no evidence of heterogeneity and publication bias.

Conclusions:

Our findings suggest that high vitamin D status is weakly associated with low breast cancer risk but strongly associated with better breast cancer survival.     

Alcohol intake and endometrial cancer risk: a meta-analysis of prospective studies

Background:

Studies on alcohol intake in relation to endometrial cancer risk have produced inconsistent results.

Methods:

For a meta-analysis, we identified cohort studies of alcohol and endometrial cancer by a literature search of Pub-Med and Embase up to 1 March 2010 and by searching the reference lists of relevant articles.

Results:

Seven cohort studies, including 1 511 661 participants and 6086 endometrial cancer cases, were included in the dose–response random-effect meta-regression model. Compared with non-drinkers, women drinking less than 1 drink of alcohol (13 g of ethanol) per day had a lower risk for endometrial cancer; this risk was lower by 4% (95% confidence interval (95% CI): 0.93–1.00) for consumption up to 0.5 drink per day and by 7% (95% CI: 0.85–1.02) for consumption up to 1 drink. However, we found evidence of an increased risk for endometrial cancer for intakes higher than two alcoholic drinks per day: compared with non-drinkers, the risk was higher by 14% (95% CI: 0.95–1.36) for 2–2.5 drinks per day and by 25% (95% CI: 0.98–1.58) for >2.5 drinks per day.

Conclusion:

Our meta-analysis indicates a possible J-shaped relationship between alcohol intake and endometrial cancer risk.     

Age-specific risk of breast cancer in women with neurofibromatosis type 1

Background:

Young women with neurofibromatosis type 1 (NF1) are reported to have a higher risk of breast cancer than others, and this might have implications for screening programmes. Our aim was to calculate this risk.

Methods:

An all-England linked data set of hospital admissions and deaths was analysed to determine age-specific rates of breast cancer in women with NF1 and controls.

Results:

The age-specific excess risk of breast cancer, comparing the NF1 cohort with the control cohort, was elevated 6.5-fold (95% confidence interval 2.6–13.5) in women aged 30–39 years. There was a 4.4 (2.5–7.0) times higher risk among women aged 40–49.

Conclusions:

Women with NF1 develop breast cancer at younger ages than the general population.     

The association of diabetes with colorectal cancer risk: the Multiethnic Cohort

Background:

Diabetics have been found to have a greater risk of colorectal cancer than non-diabetics.

Methods:

We examined whether this relationship differed by ethnic group, cancer site or tumour stage in a population-based prospective cohort, including 3549 incident colorectal cancer cases identified over a 13-year period (1993–2006) among 199 143 European American, African American, Native Hawaiian, Japanese American and Latino men and women in the Multiethnic Cohort.

Results:

Diabetics overall had a significantly greater risk of colorectal cancer than did non-diabetics (relative risk (RR)=1.19, 95% confidence interval (CI)=1.09–1.29, P-value (P)<0.001). Positive associations were observed for colon cancer, cancers of both the right and left colon, and cancers diagnosed at a localised and regional/distant stage. The association with colorectal cancer risk was significantly modified by smoking status (P_Interaction=0.0044), with the RR being higher in never smokers (RR=1.32, 95% CI=1.15–1.53, P<0.001) than past (RR=1.19, 95% CI=1.05–1.34, P=0.007) and current smokers (RR=0.90, 95% CI=0.70–1.15, P=0.40).

Conclusion:

These findings provide strong support for the hypothesis that diabetes is a risk factor for colorectal cancer.     

Breast cancer risk following Hodgkin lymphoma radiotherapy in relation to menstrual and reproductive factors

Background:

Women treated with supradiaphragmatic radiotherapy (sRT) for Hodgkin lymphoma (HL) at young ages have a substantially increased breast cancer risk. Little is known about how menarcheal and reproductive factors modify this risk.

Methods:

We examined the effects of menarcheal age, pregnancy, and menopausal age on breast cancer risk following sRT in case–control data from questionnaires completed by 2497 women from a cohort of 5002 treated with sRT for HL at ages <36 during 1956–2003.

Results:

Two-hundred and sixty women had been diagnosed with breast cancer. Breast cancer risk was significantly increased in patients treated within 6 months of menarche (odds ratio (OR) 5.52, 95% confidence interval (CI) (1.97–15.46)), and increased significantly with proximity of sRT to menarche (P_trend<0.001). It was greatest when sRT was close to a late menarche, but based on small numbers and needing reexamination elsewhere. Risk was not significantly affected by full-term pregnancies before or after treatment. Risk was significantly reduced by early menopause (OR 0.55, 95% CI (0.35–0.85)), and increased with number of premenopausal years after treatment (P_trend=0.003).

Conclusion:

In summary, this paper shows for the first time that sRT close to menarche substantially increases breast cancer risk. Careful consideration should be given to follow-up of these women, and to measures that might reduce their future breast cancer risk.