Benign thyroid disease and dietary factors in thyroid cancer: a case-control study in Kuwait

We conducted a population-based study of 313 case-control pairs in Kuwait to examine the aetiology of thyroid cancer, the second most common neoplasm among women in this and several other countries in the Gulf region. Among the demographic variables, individuals with 12+ years of education had a significantly reduced risk of thyroid cancer (OR=0.6; 95% CI: 0.3-0.9). The average age at diagnosis (+/-s.d.) of thyroid cancer was 34.7+/-11 years in women and 39+/-13.4 years in men. History of thyroid nodule was reported only by cases (n=34; 10.9%; lower 95% CI: 12.0); and goitre by 21 cases and four controls (OR=5.3; 95% CI: 1.8-15.3). There was no significant increase in risk with history of hypothyroidism (OR=1.8) or hyperthyroidism (OR=1.7). For any benign thyroid disease, the OR was 6.4 (95% CI: 3.4-12.0); and the population attributable risk was about 26% (95% CI: 21.1-30.9). Stepwise regression analysis showed that high consumption of processed fish products (OR=2.2; 95% CI: 1.6-3.0) fresh fish (OR=0.5; 95% CI: 0.4-0.7) and chicken (OR=1.7; 95% CI: 1.2-2.3) were independently associated with thyroid cancer with significant dose-response relationships. Among the thyroid cancer patients who reported high consumption of fish products, a large majority also reported high consumption of fresh fish (98%) and shellfish (68%). No clear association emerged with consumption of cruciferous vegetables. These data support the hypothesis that hyperplastic thyroid disease is strongly related to thyroid cancer; and that habitual high consumption of various seafoods may be relevant to the aetiology of thyroid cancer. The association with chicken consumption requires further study.     

Menstrual and reproductive factors in relation to ovarian cancer risk

We assessed menstrual and reproductive factors in relation to ovarian cancer risk in a large, population-based, case-control study. 563 cases in Massachusetts and New Hampshire were ascertained from hospitals and statewide tumour registries; control women (n = 523) were selected through random digit dialing and matched to case women by age and telephone sampling unit. We used multivariate logistic regression to evaluate factors in relation to risk of ovarian cancer and the major tumour histologic subtypes. Ovarian cancer risk was reduced among parous women, relative to nulliparous women (OR = 0.4; 95% CI = 0.3-0.6). Among parous women, higher parity (P = 0.0006), increased age at first (P = 0.03) or last (P = 0.05) birth, and time since last birth (P = 0.04) were associated with reduced risk. Early pregnancy losses, abortions, and stillbirths were unrelated to risk, but preterm, term, and twin births were protective. Risk was lower among women who had breast-fed, relative to those who had not (OR = 0.7; 95% CI = 0.5-1.0), but the average duration of breast-feeding per child was unrelated to risk (P for trend = 0.21). Age at menarche and age at menopause were unrelated to risk overall, although increasing menarcheal age was protective among premenopausal women (P = 0.02). Menstrual cycle characteristics and symptoms were generally unrelated to risk, although cycle-related insomnia was associated with decreased risk (OR = 0.5; 95% CI = 0.3-0.8). We found no association between the type of sanitary product used during menstruation and ovarian cancer risk. In analyses by histologic subtype, reproductive and menstrual factors had most effect on risk of endometrioid/clear cell tumours, and least influential with regard to risk of mucinous tumours. Overall, our findings offer some support to current hypotheses of ovarian pathogenesis, and show aetiologic differences among the tumour subtypes.     

Family history of benign thyroid disease and cancer and risk of thyroid cancer

In a population-based study of 313 case-control pairs in Kuwait, we evaluated whether a family history of benign thyroid disease (BTD) and thyroid or other cancers was associated with an increased risk of thyroid cancer, the second most common neoplasm among women in this and several other Arab countries in the Gulf region. Family history of BTD was reported by 78 (24.9%) cases and 40 (12.8%) controls in 132 and 57 relatives, respectively. There was an approximately 2-fold increased risk of thyroid cancer in individuals who had a mother (Odds Ratio (OR)=2.3; 95% Confidence Intervals (95% CI): 1.1-5.1), sister(s) (OR=2.6; 95% CI: 1.3-5.3) or aunt(s) (OR=2.1; 95% CI: 0.9-5.3) with BTD; there was also a significant trend in increasing risk with an increasing number of affected female relatives (P<0.0001). Stratification by age at diagnosis of the case showed that individuals aged 相似文献   

Effect of family history,obesity and exercise on breast cancer risk among postmenopausal women

We examined effects of obesity and lifetime exercise patterns on postmenopausal breast cancer risk according to family history in a large population-based case control study conducted in Los Angeles County, California, because we hypothesized that both factors would affect risk through similar mechanistic pathways, and that their effects would be stronger among women with a family history. We studied 1883 postmenopausal breast cancer case subjects and 1628 postmenopausal control subjects ranging in age from 55-72 years. Cases were diagnosed with incident breast cancer in the late 1980s and 1990s. Controls were individually matched to case subjects on age, ethnic origin and neighborhood. In-person interviews determined known breast cancer risk factors including: height, weight, lifetime exercise, and family history of breast and other cancers. Breast cancer risk was raised among women who had at least 1 first-degree relative with breast cancer (odds ratio [OR] = 1.68; 95% confidence interval [CI] = 1.36-2.08). Risk increased with increasing levels of body-mass index (wt-kg/ht-m(2)) (p-trend = 0.005). Breast cancer risk was reduced among women who maintained, on average, 17.6 metabolic equivalent of energy expenditure (MET)-hr of activity/week from menarche onward (OR = 0.66; 95% CI = 0.48-0.90). Body-mass index, adjusted for lifetime exercise, was strongly associated with breast cancer risk among women with a positive family history of breast cancer (p-trend < 0.0001), but only weakly associated among women with no family history (p-trend = 0.08; homogeneity of trends p = 0.0005). In contrast, the risk reduction associated with exercise activity, adjusting for body-mass index, was limited to women without a family history of breast cancer (p-trend = 0.001; homogeneity of trends p = 0.005). Body-mass index and exercise activity, both modifiable risk factors for breast cancer, seem to have differential effects depending on a woman's family history of breast cancer, and may impact risk through different biological mechanisms.     

Reproductive risk factors for incident bladder cancer: Iowa Women's Health Study

We studied the association between reproductive factors and bladder cancer incidence in a prospective cohort study of 37,459 Iowa women aged 55-69 years and initially free from cancer in 1986. Women reported reproductive history and were followed prospectively through 2003. After adjusting for age and smoking, there was an inverse association between age at menopause and incident bladder cancer (n = 192). Compared with menopause at age > or =48, the hazard ratio (HR) of bladder cancer was 1.32 (95% CI; 0.90-1.94) for menopause at 43-47, and 1.60 (95% CI; 1.06-2.39) for < or =42 (p-trend = 0.02). The associations were similar for ages at natural and surgical menopause. In addition, women with a history of bilateral oophorectomy had an increased risk of bladder cancer compared with those who did not undergo bilateral oophorectomy: HR = 1.58 (95% CI; 1.12, 2.22). Finally, there was an indication of a positive association between bladder cancer and shorter lifetime years of ovulation (p-trend = 0.09). There were no associations between incident bladder cancer and age at first birth, number of births, age at menarche, use of hormone replacement therapy or any other reproductive characteristics. This study provides evidence that increased risk of bladder cancer is associated with earlier age at menopause in postmenopausal women.     

Effect of pregnancy as a risk factor for breast cancer in BRCA1/BRCA2 mutation carriers

Early age at first birth and multiparity have been associated with a decrease in the risk of breast cancer in women in the general population. We examined whether this relationship is also present in women at high risk of breast cancer due to the presence of a mutation in either of the 2 breast cancer susceptibility genes, BRCA1 or BRCA2. We performed a matched case-control study of 1,260 pairs of women with known BRCA1 or BRCA2 mutations, recruited from North America, Europe and Israel. Women who had been diagnosed with breast cancer were matched with unaffected control subjects for year of birth, country of residence, and mutation (BRCA1 or BRCA2). Study subjects completed a questionnaire detailing their reproductive histories. Odds ratios (ORs) and 95% confidence intervals (CIs) were derived by conditional logistic regression. Among BRCA1 carriers, parity per se was not associated with the risk of breast cancer (OR for parous vs. nulliparous = 0.94; 95% CI = 0.75-1.19; p = 0.62). However, women with a BRCA1 mutation and 4 or more children had a 38% decrease in breast cancer risk compared to nulliparous women (OR = 0.62; 95% CI = 0.41-0.94). In contrast, among BRCA2 carriers, increasing parity was associated with an increased risk of breast cancer; women with 2 or more children were at approximately 1.5 times the risk of breast cancer as nulliparous women (OR = 1.53; 95% CI = 1.01-2.32; p = 0.05). Among women with BRCA2 mutations and who were younger than age 50, the (adjusted) risk of breast cancer increased by 17% with each additional birth (OR = 1.17; 95% CI = 1.01-1.36; p = 0.03). There was no significant increase in the risk of breast cancer among BRCA2 carriers older than 50 (OR for each additional birth = 0.97; 95% CI = 0.58-1.53; p = 0.92). In the 2-year period following a birth, the risk of breast cancer in a BRCA2 carrier was increased by 70% compared to nulliparous controls (OR = 1.70; 95% CI = 0.97-3.0). There was a much smaller increase in breast cancer risk among BRCA2 carriers whose last birth was 5 or more years in the past (OR = 1.24; 95% CI = 0.79-1.95). A modest reduction in risk of breast cancer was observed among BRCA1 carriers with 4 or more births. Among BRCA2 carriers, increasing parity was associated with a significant increase in the risk of breast cancer before age 50 and this increase was greatest in the 2-year period following a pregnancy.     

Impact of reproductive factors and lactation on breast carcinoma in situ risk

Incidence rates for breast carcinoma in situ (CIS) have increased markedly over the past 20 years. Breast CIS, detected primarily on mammography, now represents 30-45% of all screened detected breast cancers. We conducted a large population-based case-control study to evaluate the impact of reproductive factors and lactation on breast CIS risk. Case subjects were newly diagnosed with breast CIS at ages 35-64 years between March 1, 1995 and May 31, 1998 (n = 567), resided in Los Angeles County and were born in the United States. Control subjects (n = 614), identified through random digit dialing, fulfilled the same eligibility criteria and were required to have had at least one screening mammogram in the 2-year period before their interview. Women with a positive family history of breast cancer had a 2-fold increase in breast CIS risk. Parous women were at reduced risk relative to nulligravid women (odds ratio [OR] = 0.67, 95% confidence interval [CI] = 0.46-1.00). Among nulliparous women, pregnancy was unrelated to breast CIS risk. Among parous women, risk declined with each additional term pregnancy (p-trend = 0.003). No associations were found with age at first term pregnancy, induced abortion or miscarriage. Long duration of breast-feeding (> or =24 months) was associated with increased risk (OR = 2.00, 95% CI = 1.11-3.60). The observed effects of family history and pregnancy on breast CIS risk are consistent with those observed for invasive breast cancer. The results for breast-feeding are contrary to what has been observed in studies of invasive breast cancer.     

Serum concentrations of estrogens, sex hormone-binding globulin, and androgens and risk of breast cancer in postmenopausal women

We assessed the relationship between serum concentrations of estrogens, androgens, and sex hormone-binding globulin and risk of breast cancer among postmenopausal women. Study participants provided serum prior to breast biopsy or mastectomy in 3 hospitals in Grand Rapids, Michigan between 1977 and 1987. A total of 179 subjects with localized breast cancer were compared to 152 subjects with nonproliferative breast changes that have not been associated with elevated breast cancer risk. Increasing serum concentrations of estrone and estrone sulfate were associated with increases in breast cancer risk; the odds ratios (ORs) in the fourth quartiles compared to the first were 2.3 (95% confidence interval (CI) 1.1-4.6) for both (p-trend = 0.02 and 0.03, respectively). Estradiol and bioavailable estradiol concentrations were associated with nonstatistically significant increases in risk. Androstenediol levels were associated with risk (p-trend = 0.01); the OR in the fourth compared to the first quartile was 2.2 (95% CI 1.0-4.6). Testosterone, dehydroepiandrosterone and androstenedione levels were not associated with increased risk. Sex hormone-binding globulin was associated with a nonsignificant decrease in risk. Associations with estrone and estrone sulfate persisted after adjustment for androstenediol (ORs for fourth compared to first quartiles were 2.0 (95% CI 0.9-4.5) and 2.2 (95% CI 1.0-4.6), respectively (p-trend = 0.16 for both). The association with androstenediol was attenuated after adjustment for estrone (OR for fourth compared to first quartile was 1.6 (95% CI 0.7-3.6); p-trend = 0.13). Higher serum concentrations of estrogens were associated with increased breast cancer risk in postmenopausal women. Androgen levels were not independently associated with substantially increased risk.     

Analysis of menstrual, reproductive, and life-style factors for breast cancer risk in Turkish women

The aim of this study was to investigate the association between menstrual, reproductive, and life-style factors and breast cancer in Turkish women. In a hospital-based case-control study in Ankara, 622 patients with histologically confirmed breast cancer were compared with 622 age-matched controls, admitted to the same hospital for acute and non-neoplastic diseases. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI) related to risk factors. Overall, menopausal status and age at menopause were found to be significantly associated with breast cancer. Having a full-term pregnancy and early age at first birth were associated with decreased breast cancer risk (OR=0.45, 95% CI=0.30–0.66; OR=0.34, 95% CI=0.22–0.53, respectively). Postmenopausal women with lactation longer than 48 mo had reduced risk of breast cancer (OR=0.36, 95% CI=0.14–0.93). In conclusion, decreased parity, late age at first birth, early menopause, and shorter duration of lactation were the most important determinants of breast cancer risk in Turkish women.     

Effects of Menstrual and Reproductive Factors on the Risk of Breast Cancer: Meta-analysis of the Case-Control Studies in Japan

To elucidate the magnitude of the effect of menstrual and reproductive factors on breast cancer occurrence among Japanese women, we reviewed eight case-control studies previously conducted in Japan and used a quantitative method (meta-analysis) to summarize the data. While individual studies have different methods and populations, the estimated odds ratios (ORs) in the studies were statistically homogeneous for all study variables. It was confirmed that early age at menarche, late age at first birth, and premenopausal status are significantly associated with risk of breast cancer; an estimated combined OR of 0.68 (95% confidence interval (CI): 0.59-0.77) was obtained for women with onset of menstruation after age 16 compared to those before age 14. Nulliparous women had higher risk than women with first birth before age 25 (OR=1.56 95%, CI: 1.27-1.91). The OR for women with first birth after age 35 was 2.26 (95% CI: 1.85-2.77) compared to women at first birth before age 25. Premenopausal women had a higher risk than women with menopause before age 50 (OR=2.21, 95% CI: 1.53-3.20). We also found a significant protective effect of high parity after controlling for age at first birth and the other menstrual factors. The OR estimate for 3 or more births compared to nulliparity was 0.68 (95% CI: 0.54-0.86). The meta-analysis provided quantitative estimates of breast cancer risk among Japanese women with improved precision.     

Clinical Risk Factor Analysis for Breast Cancer: 568,000 Subjects Undergoing Breast Cancer Screening in Beijing, 2009

Objectives: Although there are many reports about the risk of breast cancer, few have reported clinicalfactors including history of breast-related or other diseases that affect the prevalence of breast cancer. This studyexplores these risk factors for breast cancer cases reported in Beijing in 2009. Materials and Methods: Datawere derived from a Beijing breast cancer screening performed in 2009, of 568,000 women, from 16 districts ofBeijing, all aged between 40 and 60 years. In this study, multilevel statistical modeling was used to identify clinicalfactors that affect the prevalence of breast cancer and to provide more reliable evidence for clinical diagnosticsby using screening data. Results and Conclusion: Those women who had organ transplants, compared withthose with none, were associated with breast cancer with an odds ratio (OR) = 65.352 [95% confidence interval(CI): 8.488-503.165] and those with solid breast mass compared with none had OR = 1.384 (95% CI: 1.022-1.873). Malignant tendency was strongly associated with increased risk of breast cancer, OR = 207.999(95%CI: 151.950-284.721). The risk of breast cancer increased with age, OR1 = 2.759 (95% CI: 1.837-4.144, 56-60 vs.40-45), OR2 = 2.047 (95% CI: 1.394-3.077, 51-55 vs. 40-45), OR3 = 1.668 (95% CI: 1.145-2.431). Normal resultsof B ultrasonic examination show a lower risk among participants, OR= 0.136 (95% CI: 0.085-0.218). Thosewomen with ductal papilloma compared with none were associated with breast cancer, OR=6.524 (95% CI:1.871-22.746). Therefore, this study suggests that clinical doctors should pay attention to these high-risk factors.     

Dietary Carbohydrate,Fiber and Sugar and Risk of Breast Cancer According to Menopausal Status in Malaysia

Background: Dietary carbohydrate, fiber and sugar intake has been shown to play a role in the etiology ofbreast cancer, but the findings have been inconsistent and limited to developed countries with higher cancerincidence. Objective: To examine the association of premenopausal and postmenopausal breast cancer risk withdietary carbohydrate, fiber and sugar intake. Materials and Methods: This population based case-control studywas conducted in Malaysia with 382 breast cancer patients and 382 controls. Food intake pattern was assessed viaan interviewer-administered food frequency questionnaire. Logistic regression was used to compute odds ratios(OR) with 95% confidence intervals (CI) and a broad range of potential confounders were included in analysis.Results: A significant two fold increased risk of breast cancer among premenopausal (OR Q4 to Q1=1.93, 95%CI:1.53-2.61, p-trend=0.001) and postmenopausal (OR Q4 to Q1=1.87, 95%CI: 1.03-2.61, p-trend=0.045) womenwas observed in the highest quartile of sugar. A higher intake of dietary fiber was associated with a significantlylower breast cancer risk among both premenopausal (ORQ4 to Q1=0.31, 95%CI: 0.12-0.79, p-trend=0.009) andpostmenopausal (ORQ4 to Q1=0.23, 95%CI: 0.07-0.76, p-trend=0.031) women. Conclusions: Sugar and dietaryfiber intake were independently related to pre- and postmenopausal breast cancer risk. However, no associationwas observed for dietary carbohydrate intake.     

Reproductive and hormonal risk factors for thyroid cancer in Los Angeles County females.

We conducted an individually matched case-control study (292 pairs) of female thyroid cancer patients to examine the role of reproductive history and exogenous hormones in this disease. Radiation treatment to the head or neck [28 cases and 2 controls exposed; odds ratio (OR), 14.0; 95% confidence interval (CI), 3.5-121.3] and certain benign thyroid diseases (including adolescent thyroid enlargement, goiter, and nodules or tumors) were strongly associated with thyroid cancer. Irregular menstruation increased risk (OR, 1.8; 95% CI, 0.9-3.7). Age at menarche and pregnancy history were not related to disease. Women with natural menopause and hysterectomized women without oophorectomy had no increase in risk, but disease risk was elevated in women with bilateral oophorectomy (OR, 6.5; 95% CI, 1.1-38.1). In general, use of oral contraceptives and other exogenous estrogens was not associated with thyroid cancer. However, risk increased with number of pregnancies in women using lactation suppressants (P = 0.03) and decreased with duration of breastfeeding (P = 0.04). These data provide only limited support for the hypothesis that reproductive and hormonal exposures are responsible for the marked excess of thyroid cancer risk in adult females.     

Breast Cancer Risk From Modifiable and Non-Modifiable Risk Factors among Women in Southeast Asia: A Meta-Analysis

Objective: The aim of this study was to determine breast cancer risk from modifiable and non-modifiable factors among women in Southeast Asia. Methods: This meta-analysis was performed on research articles on breast cancer risk factors in PubMed, ProQuest and EBSCO databases published between 1997 and October 2017. Pooled odds ratios (OR) are calculated using fixed and random-effect models. Data were processed using Review Manager 5.3 (RevMan 5.3). Results: From a total of 1,211 articles, 15 studies (1 cohort and 14 case control studies) met the criteria for systematic review. Meta-analysis results showed that of the known modifiable risk factors for breast cancer, parity (nulipara) had the highest odd ratio (OR = 1.85 [95% CI 1.47-2.32]) followed by body mass index (overweight) (OR = 1.61 [95% CI 1.43-1.80]) and use of oral contraceptives (OR = 1.27 [95% CI 1.07-1.51]). Of non-modifiable risk factors, family history of breast cancer had the highest odd ratio (OR = 2.53 [95% CI 1.25-5.09]), followed by age (≥ 40 years) (OR = 1.53 [95% CI 1.34-1.76]) and menopausal status (OR = 1.44 [95% CI 1.26-1.65]). Conclusion: This analysis confirmed associations between both modifiable risk factors (parity, body mass index and use of oral contraceptives) and non-modifiable risk factors (family history of breast cancer, age and menopausal status) with breast cancer.     

Tubal ligation,hysterectomy and epithelial ovarian cancer in the New England Case–Control Study

Previous studies have observed that tubal ligation and hysterectomy are associated with a decreased risk of ovarian cancer; however, little is known about whether these associations vary by surgical characteristics, individual characteristics or tumor histology. We used logistic regression to examine tubal ligation, simple hysterectomy and hysterectomy with unilateral oophorectomy in relation to risk of epithelial ovarian cancer in the New England Case–Control Study. Our primary analysis included 2,265 cases and 2,333 controls. Overall, tubal ligation was associated with a lower risk of epithelial ovarian cancer [odds ratio (OR) = 0.82, 95% confidence interval (CI): 0.68–0.97], especially for endometrioid tumors (OR = 0.45, 95% CI: 0.29–0.69). The inverse association between tubal ligation and ovarian cancer risk was stronger for women who had undergone the procedure at the time of last delivery (OR = 0.60, 95% CI: 0.42–0.84) rather than at a later time (OR = 0.93, 95% CI: 0.75–1.15). Overall, simple hysterectomy was not associated with ovarian cancer risk (OR: 1.09, 95% CI: 0.83–1.42), although it was associated with a nonsignificant decreased risk of ovarian cancer among women who underwent the procedure at age 45 or older (RR: 0.64, 95% CI: 0.40–1.02) or within the last 10 years (OR = 0.65, 95% CI: 0.38–1.13). Overall, women who had a hysterectomy with a unilateral oophorectomy had significantly lower risk of ovarian cancer (OR = 0.65, 95% CI: 0.45–0.94). In summary, tubal ligation and hysterectomy with unilateral oophorectomy were inversely associated with ovarian cancer risk in a large population‐based case–control study. Additional research is necessary to understand the potential biologic mechanisms by which these procedures may reduce ovarian cancer risk.     

Anthropometric factors and breast cancer risk among urban and rural women in South India: a multicentric case-control study

Breast cancer (BC) incidence in India is approximately twice as high in urban women than in rural women, among whom we investigated the role of anthropometric factors and body size. The study was conducted at the Regional Cancer Centre, Trivandrum, and in three cancer hospitals in Chennai during 2002-2005. Histologically confirmed cases (n=1866) and age-matched controls (n=1873) were selected. Anthropometric factors were measured in standard ways. Information on body size at different periods of life was obtained using pictograms. Odds ratios (OR) of BC were estimated through logistic regression modelling. Proportion of women with body mass index (BMI)>25.0 kg/m(2), waist size >85 cm and hip size >100 cm was significantly higher among urban than rural women. Risk was increased for waist size >85 cm (pre-menopausal: OR=1.24, 95% CI: 0.96-1.62; post-menopausal: 1.61, 95% CI: 1.22-2.12) and hip size >100 cm (pre-menopausal: OR=1.47, 95% CI: 1.05-2.06; post-menopausal 2.42, 95% CI: 1.72-3.41). Large body size at age 10 (OR=1.75, 95% CI: 1.01-3.03) and increased BMI (OR=1.33, 95% CI: 1.05-1.69 for 25.0-29.9 kg/m(2) and OR=1.56, 95% CI: 1.03-2.35 for 30+ kg/m(2)) were associated with pre-menopausal BC risk. Our data support the hypotheses that increased anthropometric factors are risk factors of BC in India.     

Risk factors for breast cancer among young women in southern Iran

Age standardized incidence rates of breast cancer in developed countries is nearly threefold higher than in developing countries. Iran has had one of the lowest incidence rates for breast cancer in the world, but during the last four decades increasing incidence rates of breast cancer made it the most prevalent cancer in Iranian women. After adjustment for age, Iranian young women are at relatively higher risk of breast cancer than their counterparts in developed countries. The purpose of this study was to investigate some established risk factors of breast cancer in Iranian young women. A hospital-based case control study comprising 521 women with histologically confirmed, incident breast cancer and 521 controls frequency-matched by age and province of residence was conducted. Logistic regression performed to investigate associations of reproductive and anthropometric factors with breast cancer risk. In multivariate analysis, family history [odds ratio (OR): 1.61; 95% confidence interval (CI): 1.07-2.42], oral contraceptives (OC) usage (OR: 1.52; 95% CI: 1.11-2.08), low parity (OR parity ≥ 3 vs. 1-2: 0.33; 95% CI: 0.23-0.49), employment (OR: 1.83; 95% CI: 1.05-3.23) and shorter period of breast feeding (OR ≥ 37 months vs. < 37: 0.61; 95% CI: 0.44-0.84) were related to a higher risk of breast cancer in young women. This was the first study focusing on risk factors of breast cancer in Iranian young women. The trend of decreasing parity and shortened duration of breast feeding along with OC usage might partly explain the rapid rising of breast cancer incidence in Iranian young women.     

Parity and risk of thyroid cancer: a nested case-control study of a nationwide Swedish cohort

The association between parity and risk of thyroid cancer was examined in a case-control study nested within a cohort of Swedish women born 1925–60. A total of 1,409 cases of thyroid cancer were compared with 7,019 agematched controls. Odds ratios (OR) and 95 percent confidence intervals (CI) were calculated as estimates of relative risk. A weak association was found between parity and risk of thyroid cancer (OR for ever-parous women cf nulliparous was 1.1, CI=1.0–1.3). For the subset of papillary cancers, there was a significantly increased risk (OR for ever-parous cf nulliparous = 1.3, CI=1.0–1.6), and among women diagnosed at the age of 50 or older, there was a positive linear trend with increasing number of livebirths. Women during the first year after a livebirth had an increased risk of thyroid cancer compared with women who delivered 10 or more years before; this association was most prominent among uniparous women (OR=2.5, CI=1.1–5.9). An increased risk was also apparent for age over 20 years at livebirth (among uniparous women) and age over 25 years at last livebirth (among multiparous women). A negligible effect of parity on thyroid cancer risk was seen, but each livebirth may have a short-term and age-dependent promoting effect.Authors are with the Department of Cancer Epidemiology, University Hospital, Uppsala, Sweden (M.R. Galanti, M. Lambe, A. Ebbora, R. Sparda B. Pettersson): Department of Social Medicine, University Hospital, Uppsala, Sweden (M. Lambe); Department of Epidemiology, Harvard School of Public Health, Boston, USA (A. Ekbom). Address correspondence to Dr M. Rosaria Galanti, Department of Cancer Epidemiology, University Hospital, S-751 85 Uppsala, Sweden. This work was supported in part by grant n. 3136-B92-02XBB from the Swedish Cancer Society.     

Do thyroid disorders increase the risk of breast cancer?

The objective of this study was to determine whether thyroid disorders or treatment of such disorders affects the risk of breast cancer. Subjects aged 35-64 years were participants in the National Institute of Child Health and Human Development Women's Contraceptive and Reproductive Experiences Study, a population-based, case-control study of invasive breast cancer that was carried out at five sites in the United States. In-person interviews were completed for 4575 women (cases) with breast cancer (2953 white and 1622 black) and 4682 control women (3021 white and 1661 black). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multiple logistic regression methods. Models included adjustment for age (5-year age groups), race (white or black), and site. A history of any thyroid disorder (OR = 1.1, 95% CI = 0.9-1.2) was not associated with breast cancer risk. Only women with a history of thyroid cancer had an increased risk, but this was restricted to parous women (parous OR = 3.4, 95% CI = 1.5-8.1; nulliparous OR = 0.5, 95% CI = 0.04-5.1). Breast cancer risk was not associated with treatment for thyroid disorders. There was no statistical interaction between thyroid disorders, thyroid treatments, and race, menopausal status, or parity. We found no association between thyroid disorders or their associated treatments and the risk of breast cancer.     

Risk factors for breast cancer in Turkish women with early pregnancies and long-lasting lactation--a case-control study

A hospital-based case-control study was carried out among 504 women with breast cancer and 610 controls to analyse the risk factors for breast cancer in Turkey. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for each risk factor were obtained from logistic regression analysis. Risk factors for breast cancer were found to be long-term lactation (> or = 5 years versus never OR 0.31, 95% CI 0.12-0.79), young age at menarche (< 15 years versus > or = 15 OR 1.72, 95% CI 1.30-2.28), late age at first full-term pregnancy (> or = 30 versus < 20 OR 2.86, 95% CI 1.32-6.21), oral contraceptive use (ever versus never OR 1.51, 95% CI 1.10-2.08), positive family history (positive versus negative OR 2.81, 95% CI 1.35-5.82), and menstrual irregularity (yes versus no OR 1.61, 95% CI 1.05-2.49). The results of the present study will lead to a better understanding of the risk factors for breast cancer in a developing country.