Weight and weight changes in early adulthood and later breast cancer risk

Obesity is a well‐established cause of postmenopausal breast cancer. However, early life adiposity is inversely associated with breast cancer incidence. To understand these conflicting relations, we use validated measures to assess adiposity in childhood and late adolescence, as well as weight change, in relation to total invasive breast cancer incidence and receptor subtypes. We conducted a prospective observational study among 74,177 women from the Nurses’ Health Study from 1980–2012, with updated risk factors every 2 years during which 4,965 incident invasive breast cancers occurred. Overall, weight at age 18 was inversely associated with both premenopausal (HR per 30 kg = 0.52, 95% CI = 0.39–0.71) and postmenopausal (HR per 30 kg = 0.81, 95% CI = 0.72–0.92) breast cancer which was largely explained by adiposity at age 10. Long‐term weight gain from age 18 both during premenopause and postmenopause were positively associated with postmenopausal breast cancer risk. However, premenopausal weight gain was not related to premenopausal breast cancer risk. Furthermore, weight gain since age 18 was positively associated with ER+/PR+ postmenopausal breast cancer (HR per 30 kg = 1.50, 95% CI = 1.36–1.65) but not ER+/PR? (HR per 30 kg = 0.96, 95% CI = 0.78–1.19) or ER?/PR? (HR per 30 kg = 1.16, 95% CI = 0.95–1.42) postmenopausal breast cancer. Overall, 17% of ER+/PR+ postmenopausal breast cancer and 14% of total postmenopausal breast cancer are attributable to weight gain of > 5 kg since age 18.     

Weight gain prior to diagnosis and survival from breast cancer.

BACKGROUND: To examine the effects of prediagnostic obesity and weight gain throughout the life course on survival after a breast cancer diagnosis, we conducted a follow-up study among a population-based sample of women diagnosed with first, primary invasive, and in situ breast cancer between 1996 and 1997 (n = 1,508). METHODS: In-person interviews were conducted shortly after diagnosis to obtain information on height and weight at each decade of life from age 20 years until 1 year before diagnosis. Patients were followed to determine all-cause (n = 196) and breast cancer-specific (n = 127) mortality through December 31, 2002. RESULTS: In multivariate Cox proportional hazards models, obese women had increased mortality due to breast cancer compared with ideal weight women among those who were premenopausal at diagnosis [hazard ratio (HR), 2.85; 95% confidence interval (95% CI), 1.30-6.23] and postmenopausal at diagnosis (HR, 1.91; 95% CI, 1.06-3.46). Among women diagnosed with premenopausal breast cancer, those who gained >16 kg between age 20 years and 1 year before diagnosis, compared with those whose weight remained stable (+/-3 kg), had more than a 2-fold elevation in all-cause (HR, 2.45; 95% CI, 0.96-6.27) and breast cancer-specific mortality (HR, 2.09; 95% CI, 0.80-5.48). Women diagnosed with postmenopausal breast cancer who gained more than 12.7 kg after age of 50 years up to the year before diagnosis had a 2- to 3-fold increased risk of death due to all-causes (HR, 2.69; 95% CI, 1.63-4.43) and breast cancer (HR, 2.95; 95% CI, 1.36-6.43). CONCLUSIONS: These results indicate that high levels of prediagnostic weight and substantial weight gain throughout life can decrease survival in premenopausal and postmenopausal breast cancer patients.     

Risk Factor Analysis for Breast Cancer in Premenopausal and Postmenopausal Women of Punjab,India

Objective: Amritsar, the second largest town of agrarian state of Punjab, India reports high number of breast cancer cases every year. The present study investigated the etiology of breast cancer using various obesity indices and other epidemiological factors among breast cancer patients residing in and around Amritsar city. Methods: In this case control study, risk factors for breast cancer were analyzed in 542 female subjects: 271 females with breast cancer patients and 271 unrelated healthy females matched for age as control females. Results: Bivariate analysis for risk factors in cases and controls showed a lower risk (OR=0.65, 95% CI 0.43-0.99, p=0.04) in obese cases with BMI≥25kg/m2 as compared to subjects with normal BMI. Risk factor analysis showed that parameter which provided risk for cancer in postmenopausal women was obesity and in premenopausal women was parity. Postmenopausal women with BMI (overweight: OR=0.39, 95% CI 0.17-0.92, p=0.03; obese: OR= 0.26, 95% CI 0.13-0.52, p=0.00), WC (OR=0.17, 95% CI 0.05-0.52, p=0.00) and WHtR (p=0.02) had highr risk. Premenopausal women with 3 or less than 3 children had a higher risk (OR=5.54, 95 % CI 2.75-11.19, p=0.00) than postmenopausal women when compared to women with more than 3 children. Binary logistic regression analysis revealed that low parity (≤3) substantially increased the risk for breast cancer (OR=4.80, 95% CI 2.34-9.85, p=0.00) in premenopausal women. Conclusion: Obesity, parity associated breast cancer risk and reduced breastfeeding cumulatively predispose the premenopausal women of this region to higher risk of breast cancer.     

The association of soy food consumption with the risk of subtype of breast cancers defined by hormone receptor and HER2 status

Soy food intake has previously been associated with reduced breast cancer risk. Epidemiological evidence for subgroups of breast cancer, particularly by menopausal and hormone receptor status, is less consistent. To evaluate the role of hormone receptor and menopausal status on the association between soy food intake and breast cancer risk, we measured usual soy food intake in adolescence and adulthood via food frequency questionnaire in 70,578 Chinese women, aged 40–70 years, recruited to the Shanghai Women's Health Study (1996–2000). After a median follow‐up of 13.2 years (range: 0.01–15.0), 1,034 incident breast cancer cases were identified. Using Cox models, we found that adult soy intake was inversely associated with breast cancer risk [hazard ratio (HR) for fifth versus first quintile soy protein intake = 0.78; 95% confidence interval (CI):0.63–0.97]. The association was predominantly seen in premenopausal women (HR = 0.46; 95% CI:0.29‐0.74). Analyses further stratified by hormone receptor status showed that adult soy intake was associated with significantly decreased risk of estrogen receptor (ER)+/progesterone receptor (PR)+ breast cancer in postmenopausal women (HR = 0.72; 95% CI:0.53–0.96) and decreased risk of ER?/PR? breast cancer in premenopausal women (HR = 0.46; 95% CI:0.22–0.97). The soy association did not vary by human epidermal growth factor‐2 (HER2) status. Furthermore, we found that high soy intake during adulthood and adolescence was associated with reduced premenopausal breast cancer risk (HR = 0.53; 95% CI: 0.32–0.88; comparing third vs. first tertile) while high adulthood soy intake was associated with postmenopausal breast cancer only when adolescent intake was low (HR = 0.63; 95% CI: 0.43–0.91). Our study suggests that hormonal status, menopausal status and time window of exposure are important factors influencing the soy‐breast cancer association.     

General and abdominal obesity and survival among young women with breast cancer.

Among postmenopausal women, obesity is linked to increased risk of breast cancer and poorer subsequent survival. For premenopausal women, obesity may reduce incidence, but less is known about its effect on prognosis, particularly for abdominal obesity. This study investigated whether general or abdominal obesity at diagnosis influenced survival in a cohort of young women with breast cancer. A population-based follow-up study was conducted among 1,254 women ages 20 to 54 who were diagnosed with invasive breast cancer between 1990 and 1992 in Atlanta or New Jersey. Women were interviewed within several months of diagnosis and asked about their weight and height at age 20 and in the year before diagnosis. Study personnel did anthropometric measures at the interview. With 8 to 10 years of follow-up, all-cause mortality status was determined using the National Death Index (n = 290 deaths). Increased mortality was observed for women who were obese [body mass index (BMI), > or =30] at the time of interview compared with women of ideal weight [BMI, 18.5-24.9; stage- and income-adjusted hazard ratio (HR), 1.48; 95% confidence interval (95% CI), 1.09-2.01]. A similar result was seen for the highest versus lowest quartile of waist-to-hip ratio (HR, 1.52; 95% CI, 1.05-2.19). Strong associations with mortality were found for women who were obese at age 20 (HR, 2.49; 95% CI, 1.15-5.37) or who were overweight/obese (BMI, > or =25) at both age 20 and the time of interview (HR, 2.22; 95% CI, 1.45-3.40). This study provides evidence that breast cancer survival is reduced among younger women with general or abdominal obesity.     

Weight Gain and Alcohol Drinking Associations with Breast Cancer Risk in Japanese Postmenopausal Women - Results from the Japan Collaborative Cohort (JACC) Study

Background: We investigated four factors, height, weight gain since age 20, physical activity, and alcohol drinking, for associations with risk of breast cancer (BC) according to menopausal status, using the latest data of the Japan Collaborative Cohort Study (JACC Study). Materials and Methods: We confined the analysis to 24 areas available of cancer incidence information, excluding women with a previous diagnosis of BC. Baseline data were collected from 38,610 (9,367 premenopausal, and 29,243 postmenopausal) women during 1988 and 1990. The study subjects were followed-up at the end of 2009, and 273 (84 premenopausal, and 189 postmenopausal) cases of BC were newly diagnosed in 501,907 person-years. The Cox model was used to estimate a hazards ratio (HR) and its 95% confidence interval (CI) of BC risk. Results: As a result of the multivariate analysis adjusting for age at baseline survey, age at menarche, number of live births, and, age at first delivery, weight gain since age 20 of 6.7 kg-9.9 kg, and 10.0 kg were significantly associated with increased risk for postmenopausal BC (HR=2.48, 95% CI 1.40-4.41, and, HR=2.94, 95% CI 1.84-4.70, respectively). Significantly increased trend of BC risk was also observed in weight gain since age 20 (p for trend, p<0.001). Amount of ethanol intake per day15.0 g was significantly associated with increased risk for postmenopausal BC in the multivariable-adjusted analysis (HR=2.74, 95% CI 1.32-5.70). Conclusions: Higher weight gain in adulthood and larger amounts of ethanol intake were significantly associated with increased risk of BC in Japanese postmenopausal women. None of the investigated factors were significantly associated with BC risk in Japanese premenopausal women.     

Circulating insulin-like growth factor-I and binding protein-3 and the risk of breast cancer.

Four meta-analyses and literature reviews have concluded that a positive association exists between circulating levels of insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) and breast cancer risk for premenopausal but not postmenopausal women. Recently, a large prospective study reported an association with IGF-I and IGFBP-3 concentration for breast cancer diagnosed after, but not before, the age of 50 years; and in a large cohort of primarily premenopausal women, IGF-I and IGFBP-3 were not associated with breast cancer risk. We did a case-cohort study within the Melbourne Collaborative Cohort Study, which included a random sample of 1,901 women (subcohort) and 423 breast cancer cases diagnosed during a mean of 9.1 years of follow-up. IGF-I and IGFBP-3 concentrations were measured in plasma collected at baseline. The association between quartiles of IGF concentration and breast cancer risk was tested using a Cox model adjusted for known and potential confounders. The hazard ratio (HR) for breast cancer comparing the fourth with the first quartiles was 1.20 [95% confidence interval (95% CI), 0.87-1.65] for IGF-I and 1.09 (95% CI, 0.78-1.53) for IGFBP-3. Both associations varied with age: for IGF-I, the HRs for breast cancer comparing the fourth with the first quartiles were 0.60 (95% CI, 0.25-1.45) before age 50 and 1.61 (95% CI, 1.04-2.51) after age 60 (test for the log-linear trend of HR according to age, P = 0.05); for IGFBP-3, the HRs were 0.79 (95% CI, 0.34-1.83) before age 50 and 1.62 (95% CI, 1.03-2.55) after age 60 (test for log-linear trend, P = 0.08). IGF-I and IGFBP-3 were positively associated with breast cancer risk in older women but not in younger women. More prospective studies are needed to clarify the age dependence of the association between IGF-I and IGFBP-3 and breast cancer.     

The association of plasma DHEA and DHEA sulfate with breast cancer risk in predominantly premenopausal women.

Concentrations of adrenal androgens are positively associated with postmenopausal breast cancer risk; however, results in premenopausal women are conflicting. Therefore, we conducted a prospective nested case-control study within the Nurses' Health Study II cohort to examine the relationship of DHEA and DHEA sulfate (DHEAS) with breast cancer risk in predominantly premenopausal women. Blood samples were collected from 1996 to 1999. The analysis included 317 cases of breast cancer diagnosed after blood collection and before June 1, 2003; for each case, two controls were matched on age, fasting status, time of day and month of blood collection, race/ethnicity, and timing of blood draw within the menstrual cycle. No associations were observed between DHEA or DHEAS levels and breast cancer risk overall [in situ and invasive; DHEA relative risk (RR), top versus bottom quartile, 1.2; 95% confidence interval (95% CI), 0.8-1.8, P(trend) = 0.53; DHEAS RR, 1.3; 95% CI, 0.9-2.0; P(trend) = 0.07]. However, both DHEA and DHEAS were positively associated with estrogen receptor-positive/progesterone receptor-positive breast cancer (DHEA RR, 1.6; 95% CI, 0.9-2.8, P(trend) = 0.09; DHEAS RR, 1.9; 95% CI, 1.1-3.3, P(trend) = 0.02). We observed a significant interaction by age, with an RR for DHEAS of 0.8 (95% CI, 0.4-1.5, P(trend) = 0.62) for women <45 years old and 2.0 (95% CI, 1.2-3.5, P(trend) = 0.003) for women >/=45 years old; results were similar for DHEA. Our results suggest that adrenal androgens are positively associated with breast cancer among predominately premenopausal women, especially for estrogen receptor-positive/progesterone receptor-positive tumors and among women over age 45 years.     

Risk of endometrial cancer in relationship to cigarette smoking: results from the EPIC study

Current epidemiologic evidence indicates that cigarette smoking reduces the risk of endometrial cancer. We examined data from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort to analyze further aspects of the smoking-endometrial cancer relationship, such as possible modifying effects of menopausal status, HRT use, BMI and parity. In a total of 249,986 women with smoking exposure and menopausal status information, 619 incident endometrial cancer cases were identified during 1.56 million person-years of follow-up. Among postmenopausal women, the hazard ratio (HR) for current smokers versus never smokers was 0.70 (95% CI = 0.53-0.93), while it was 1.75 (95% CI = 1.13-2.70) among premenopausal women at recruitment. After adjustment for risk factors, the HR for postmenopausal women was slightly attenuated to 0.78 (95% CI = 0.59-1.03). No heterogeneity of effect was observed with HRT use or BMI. Among premenopausal women, current smokers of more than 15 cigarettes per day or who smoked for 30 years or more at the time of recruitment had a more than 2-fold increased risk of endometrial cancer compared to never smokers (HR = 2.54; 95% CI = 1.47-4.38 and HR = 2.23; 95% CI = 1.04-4.77, respectively). Past smoking was not associated with endometrial cancer risk, either among pre- or postmenopausal women. In this prospective study, we observed an increased risk of endometrial cancer with cigarette smoking in premenopausal women. The reduction of endometrial cancer risk observed among postmenopausal women does not have direct public health relevance since cigarette smoking is the main known risk factor for cancer.     

Body size and breast cancer risk: findings from the European Prospective Investigation into Cancer And Nutrition (EPIC)

The evidence for anthropometric factors influencing breast cancer risk is accumulating, but uncertainties remain concerning the role of fat distribution and potential effect modifiers. We used data from 73,542 premenopausal and 103,344 postmenopausal women from 9 European countries, taking part in the EPIC study. RRs from Cox regression models were calculated, using measured height, weight, BMI and waist and hip circumferences; categorized by cohort-wide quintiles; and expressed as continuous variables, adjusted for study center, age and other risk factors. During 4.7 years of follow-up, 1,879 incident invasive breast cancers were identified. In postmenopausal women, current HRT modified the body size-breast cancer association. Among nonusers, weight, BMI and hip circumference were positively associated with breast cancer risk (all ptrend < or = 0.002); obese women (BMI > 30) had a 31% excess risk compared to women with BMI < 25. Among HRT users, body measures were inversely but nonsignificantly associated with breast cancer. Excess breast cancer risk with HRT was particularly evident among lean women. Pooled RRs per height increment of 5 cm were 1.05 (95% CI 1.00-1.16) in premenopausal and 1.10 (95% CI 1.05-1.16) in postmenopausal women. Among premenopausal women, hip circumference was the only other measure significantly related to breast cancer (ptrend = 0.03), after accounting for BMI. In postmenopausal women not taking exogenous hormones, general obesity is a significant predictor of breast cancer, while abdominal fat assessed as waist-hip ratio or waist circumference was not related to excess risk when adjusted for BMI. Among premenopausal women, weight and BMI showed nonsignificant inverse associations with breast cancer.     

Premenopausal levels of circulating insulin-like growth factor I and the risk of postmenopausal breast cancer

Increased levels of insulin-like growth factor I (IGF-I) may directly stimulate breast cell proliferation and promote growth and survival of transformed cells. Higher levels of IGF-I have been associated with increased risk of premenopausal breast cancer but not postmenopausal breast cancer. We investigated whether circulating levels of IGF-I prior to menopause are associated with breast cancer diagnosed after menopause in a population-based nested case-control study. Female cohort participants were enrolled in 1974 (n = 15,192) and 1989 (n = 18,724) and blood was drawn. Cases were women diagnosed with primary breast cancer at ages > or =50, of whom 152 were premenopausal at blood draw. One control was matched to each case on cohort participation, age, ethnic group, menopausal status and date of blood draw. Levels of IGF-I and IGF binding protein 3 (IGFBP-3) were measured using enzyme-linked immunoabsorbent assays. The association between IGF-I and breast cancer was determined using conditional logistic regression, adjusting for IGFBP-3. IGF-I levels decreased with age (p = 0.0001). Prior to age-stratification, IGF-I levels neither measured before nor after menopause were associated with postmenopausal breast cancer. After age-stratification, associations were suggested in the youngest premenopausal age group (upper vs. lowest third: odds ratio (OR) = 5.31, 95% confidence intervals (CI) = 0.85-33.13; p trend = 0.06) and oldest postmenopausal age group (upper vs. lowest third: OR = 3.41, 95% CI = 0.66-17.71; p trend = 0.13). The association between circulating levels of IGF-I and postmenopausal breast cancer risk may be modified by age. Increased levels of circulating IGF-I may be of particular interest in the younger premenopausal women and older postmenopausal women. Age-stratification should be undertaken in larger investigations of IGF-I levels as predictors of postmenopausal breast cancer.     

Randomized trial of fenretinide to prevent second breast malignancy in women with early breast cancer.

BACKGROUND: Fenretinide, a vitamin A analogue, has been shown to inhibit breast carcinogenesis in preclinical studies. We determined the efficacy of fenretinide in preventing a second breast malignancy in women with breast cancer. METHODS: We randomly assigned 2972 women, aged 30-70 years, with surgically removed stage I breast cancer or ductal carcinoma in situ to receive for 5 years either fenretinide orally (200 mg/day) or no treatment. The primary end point was the incidence of contralateral breast cancer or ipsilateral breast cancer 7 years after randomization. Other end points considered post hoc were the same outcomes stratified by menopausal status, incidence of distant metastases, overall mortality, and tumors in other organs. The hazards of breast cancer occurrence were determined by Cox proportional hazards regression analysis. Statistical tests were two-sided. RESULTS: At a median observation time of 97 months, there were no statistically significant differences in the occurrence of contralateral breast cancer (P =.642) or ipsilateral breast cancer (P =.177) between the two arms. However, an interaction was detected between fenretinide treatment and menopausal status in both outcomes (P for interaction in both outcomes =.045), with a possible beneficial effect in premenopausal women (contralateral breast cancer: adjusted hazard ratio [HR] = 0.66, and 95% confidence interval [CI] = 0.41-1.07; ipsilateral breast cancer: adjusted HR = 0.65, and 95% CI = 0.46-0. 92) and an opposite effect in postmenopausal women (contralateral breast cancer: adjusted HR = 1.32, and 95% CI = 0.82-2.15; ipsilateral breast cancer: adjusted HR = 1.19, and 95% CI = 0.75-1. 89). There were no statistically significant differences between the two arms in tumors in other organs, incidence of distant metastasis, and all-cause mortality. CONCLUSIONS: Fenretinide treatment of women with breast cancer for 5 years appears to have no statistically significant effect on the incidence of second breast malignancies overall, although a possible benefit was detected in premenopausal women. These studies, particularly the post hoc analyses, are considered exploratory and need to be confirmed.     

Circulating insulin and c-peptide levels and risk of breast cancer among predominately premenopausal women.

Insulin and insulin resistance have been hypothesized to increase the risk of breast cancer as insulin increases breast cell proliferation and inhibits sex hormone binding globulin. Although insulin is directly related to body weight, adiposity is inversely associated with breast cancer risk in premenopausal women but directly related to risk in postmenopausal women. To explore the association between insulin and c-peptide levels and breast cancer risk, we conducted a nested case-control study of predominantly premenopausal women within the Nurses' Health Study II cohort. From 1996 to 1999, blood samples were collected from 29,611 participants. A total of 317 cases were diagnosed after blood collection and before June 2003 and matched to 634 controls; 75% of these women were premenopausal at blood collection. Logistic regression models, controlling for breast cancer risk factors, were used to calculate relative risks (RR) and 95% confidence intervals (95% CI). Among women with fasting blood samples (n = 211 cases), insulin was suggestively inversely associated with breast cancer risk (highest versus lowest quartile: RR, 0.5; 95% CI, 0.3-1.0; P(trend) = 0.06). Among all women, c-peptide was not associated with breast cancer risk (highest versus lowest quartile: RR, 1.1; 95% CI, 0.7-1.7; P(trend) = 0.79); results were similar among fasting samples. These associations did not differ by age, body mass index, or waist-to-hip ratio. Overall, higher levels of insulin and c-peptide were not associated with a higher risk of breast cancer among predominantly premenopausal women.     

Insulin-like growth factor I (IGF-I), IGF-binding proteins, and breast cancer.

Epidemiological evidence supports a role for the insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) in the induction and progression of various cancers. Estrogen, which plays a role in the etiology of breast cancer, both regulates and is influenced by the IGF family. Risk of breast cancer associated with serum levels of IGF-I and/or IGFBPs may therefore depend upon menopausal status. A nested, case-control study was conducted on 66 women who were premenopausal and 60 who were postmenopausal at the time of diagnosis of primary breast cancer; they were selected from a cohort of 95,000 women who underwent multiphasic health check-ups > 30 years ago when enrolled in the Kaiser Permanente Medical Care Program. For each case, one control who matched by age, date of examination, and length of follow-up was chosen. Concentrations of IGF-I, insulin, glucose, and IGFBP-1, IGFBP-2, and IGFBP-3 in serum drawn at least 2 years before diagnosis (mean times of 10.5 and 15.8 years for pre- and postmenopausal cases, respectively) were compared using conditional logistic regression analysis. All statistical tests were two-sided. Serum IGF-I, adjusted for insulin, glucose, and body mass index, was weakly associated with breast cancer risk across quartiles for premenopausal women only (P for trend = 0.05). Serum IGFBP-3 was higher in premenopausal cases versus controls (P = 0.04) and showed a positive trend in risk for increasing quartiles (P for trend = 0.033). After adjusting for insulin, glucose, body mass index, and IGF-I, premenopausal women in the highest quartile of IGFBP-3 had an elevated risk of breast cancer [odds ratio (OR) = 5.28, 95% confidence interval (CI) = 1.13-24.7]. Conversely, IGFBP-3 was lower in postmenopausal cases versus controls (P = 0.04) but showed no significant trend in risk. Postmenopausal women with glucose levels in the diabetic range were at increased risk for developing breast cancer (OR = 2.06, 95% CI = 0.87-4.91), whereas those in the highest quartile of IGFBP-2 had a substantial reduction (71%) in risk relative to those in the lowest quartile (OR = 0.29, 95% CI = 0.09-0.92). Serum IGFBP-1 was not associated with breast cancer risk in either pre- or postmenopausal women. In premenopausal women, elevated serum IGF-I and IGFBP-3 are associated with increased breast cancer risk, whereas elevated serum IGFBP-2 is inversely associated with risk of postmenopausal breast cancer.     

Differential effects of reproductive factors on the risk of pre- and postmenopausal breast cancer. Results from a large cohort of French women

The aim of this study was to obtain a better understanding of the role of hormonal factors in breast cancer risk and to determine whether the effect of reproductive events differs according to age at diagnosis. It analysed the effect of age at menarche, age at first full-term pregnancy, number of full-term pregnancies and number of spontaneous abortions both on the overall risk of breast cancer and on its pre- or postmenopausal onset, using the data on 1718 breast cancer cases, obtained from a large sample of around 100000 French women participating in the E3N cohort study. The results provide further evidence that the overall risk of breast cancer increases with decreasing age at menarche, increasing age at first pregnancy and low parity. No overall effect of spontaneous abortions was observed. The effect of these reproductive factors differed according to menopausal status. Age at menarche had an effect on premenopausal breast cancer risk, with a decrease in risk with increasing age of 7% per year (P<0.05). Compared to those who had their first menstrual periods at 11 or before, women experiencing menarche at 15 or after had an RR of 0.66 (95% CI 0.45-0.97) in the premenopausal group. Age at first full-term pregnancy had an effect on both pre- and postmenopausal breast cancer risk, with significant tests showing increasing risk per year of increasing age (P=0.001 and P<0.05 respectively). A first full-term pregnancy above age 30 conveyed a risk of 1.63 (95% CI 1.12-2.38) and 1.35 (95% CI 1.02-1.78) in the pre- and postmenopausal groups respectively. A protective effect of high parity was observed only for postmenopausal breast cancer risk (P for trend test =0.001), with point estimates of 0.79 (95% CI 0.60-1.04), 0.69 (95% CI 0.54-0.88), 0.66 (95% CI 0.51-0.85) and 0.64 (95% CI 0.48-0.86) associated to a one, two, three and four or more full-term pregnancies. A history of spontaneous abortion had no significant effect on the risk of breast cancer diagnosed before or after menopause. Our results suggest that reproductive events have complex effects on the risk of breast cancer.     

Breast cancer risk in relation to history of preeclampsia and hyperemesis gravidarum: Prospective analysis in the Generations Study

Preeclampsia and hyperemesis gravidarum are pregnancy complications associated with altered sex hormone levels. Previous studies suggest preeclampsia may be associated with a decreased risk of subsequent breast cancer and hyperemesis with an increased risk, but the evidence remains unclear. We used data from the Generations Study, a large prospective study of women in the United Kingdom, to estimate relative risks of breast cancer in relation to a history of preeclampsia and hyperemesis using Cox regression adjusting for known breast cancer risk factors. During 7.5 years average follow‐up of 82,053 parous women, 1,969 were diagnosed with invasive or in situ breast cancer. Women who had experienced preeclampsia during pregnancy had a significantly decreased risk of premenopausal breast cancer (hazard ratio (HR) =0.67, 95% confidence interval (CI): 0.49–0.90) and of HER2‐enriched tumours (HR = 0.33, 95% CI: 0.12–0.91), but there was no association with overall (HR = 0.90, 95% CI: 0.80–1.02) or postmenopausal (HR = 0.97, 95% CI: 0.85–1.12) breast cancer risk. Risk reductions among premenopausal women were strongest within 20 years since the last pregnancy with preeclampsia. Hyperemesis was associated with a significantly increased risk of HER2‐enriched tumours (HR = 1.76, 95% CI: 1.07–2.87), but not with other intrinsic subtypes or breast cancer risk overall. These results provide evidence that preeclampsia is associated with a decreased risk of premenopausal and HER2‐enriched breast cancer and that hyperemesis, although not associated with breast cancer risk overall, may be associated with raised risk of HER2‐enriched tumours.     

Fruits, vegetables, and micronutrients in relation to breast cancer modified by menopause and hormone receptor status.

Whether fruit, vegetable, and antioxidant micronutrient consumption is associated with a reduction in breast cancer incidence remains unresolved. To address this issue, we analyzed data from a large population-based case-control study, with consideration given to whether the associations varied with menopausal status or with clinical characteristics of the cases' disease. Study participants completed a modified Block food frequency questionnaire, which included assessment of the frequency and portion sizes of 13 fruits and fruit juices and 16 vegetables and the use of multiple and single vitamin supplements. Statistical analyses were done on 1,463 cases and 1,500 controls. Among postmenopausal women, reduced odds ratios [OR; 95% confidence intervals (95% CI)] were noted for the highest fifth, as compared with the lowest fifth, of intake of any vegetables [0.63 (0.46-0.86); P for trend < 0.01] and leafy vegetables [0.66 (0.50-0.86); P for trend = 0.03] after controlling for age and energy intake. Adjusted ORs (95% CIs) were also decreased for postmenopausal breast cancer in relation to high intake of carotenoids, alpha-carotene, beta-carotene, lutein, and particularly lycopene [0.66 (0.48-0.90); P for trend = 0.03]. Inverse associations for fruits and vegetables were stronger for postmenopausal women with estrogen receptor (ER)+ tumors (OR, 0.65; 95% CI, 0.51-0.82) than ER- tumors (OR, 0.92; 95% CI, 0.64-1.32), but results were less consistent for micronutrients. No similarly reduced associations were observed among premenopausal women. ORs did not appreciably differ by in situ or invasive breast cancer or by whether cases had begun chemotherapy. Our results support an inverse association for fruit and vegetable intake among postmenopausal but not premenopausal breast cancer, which may be more pronounced among women with ER+ tumors.     

Seaweed consumption and the risk of thyroid cancer in women: the Japan Public Health Center-based Prospective Study

Iodine is a suspected risk factor for thyroid cancer. Seaweed accounts for about 80% of Japanese people's iodine intake. We examined the association between seaweed consumption and the risk of thyroid cancer in Japanese women. Women participating in the Japan Public Health Center-based Prospective Study (n=52 679; age: 40-69 years) were followed up for a mean of 14.5 years; 134 new thyroid cancer cases, including 113 papillary carcinoma cases, were identified. Seaweed consumption was assessed using a food-frequency questionnaire and divided into three categories: 2 days/week or less (reference); 3-4 days/week; and almost daily. The Cox proportional hazards model was applied to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Seaweed consumption was clearly associated with an increased risk of papillary carcinoma (HR for almost daily consumption compared with 2 days/week or less=1.71; 95% CI: 1.01-2.90; trend P=0.04). After stratification for menopausal status, an increased risk was observed in postmenopausal women (papillary carcinoma HR for almost daily consumption compared with 2 days/week or less=3.81, 95% CI: 1.67-8.68; trend P<0.01), but not in premenopausal women (HR=0.91, 95% CI: 0.44-1.91; trend P=0.76). This study identified a positive association between seaweed consumption and the risk of thyroid cancer (especially for papillary carcinoma) in postmenopausal women.     

The association between metabolic health,obesity phenotype and the risk of breast cancer

Beyond the current emphasis on body mass index (BMI), it is unknown whether breast cancer risk differs between metabolically healthy and unhealthy normal weight or overweight/obese women. The Sister Study is a nationwide prospective cohort study. Data came from 50,884 cohort participants aged 35 to 74 years enrolled from 2003 through 2009. Cox proportional hazards models were used to estimate multivariable adjusted hazard ratios (HR) and 95% confidence intervals (CIs) for breast cancer risk. Metabolic abnormalities considered included: high waist circumference (≥88 cm); elevated blood pressure (≥130/85 mm Hg or antihypertensive medication); previously diagnosed diabetes or antidiabetic drug treatment; and cholesterol‐lowering medication use. During follow‐up (mean, 6.4 years), 1,388 invasive breast cancers were diagnosed at least 1 year after enrollment. Compared to women with BMI <25 kg/m² with no metabolic abnormalities (metabolically healthy normal weight phenotype), women with a BMI <25 kg/m² and ≥1 metabolic abnormality (metabolically unhealthy, normal weight phenotype) had increased risk of postmenopausal breast cancer (HR = 1.26, 95% CI: 1.01–1.56), as did women with a BMI ≥25 kg/m² and no metabolic abnormalities (metabolically healthy overweight/obese phenotype) (HR = 1.24, 95% CI: 0.99–1.55). Furthermore, risk of postmenopausal breast cancer was consistently elevated in women with normal BMI and central obesity (normal weight central obesity phenotype) regardless of the criterion used to define central obesity, with HR for waist circumference ≥88 cm, waist circumference ≥80 cm, and waist‐hip ratio ≥0.85 of 1.58, 95% CI: 1.02–2.46; 1.38, 95% CI: 1.09–1.75; and 1.38, 95% CI: 1.02–1.85, respectively. There was an inverse association between premenopausal breast cancer and metabolically healthy overweight/obese phenotype (HR = 0.71, 95% CI: 0.52–0.97). Our findings suggest that postmenopausal women who are metabolically unhealthy or have central adiposity may be at increased risk for breast cancer despite normal BMI.     

Impact of premenopausal status at breast cancer diagnosis in women entered on the placebo-controlled NCIC CTG MA17 trial of extended adjuvant letrozole

BackgroundMA17 showed improved outcomes in postmenopausal women given extended letrozole (LET) after completing 5 years of adjuvant tamoxifen.Patients and methodsExploratory subgroup analyses of disease-free survival (DFS), distant DFS (DDFS), overall survival (OS), toxic effects and quality of life (QOL) in MA17 were performed based on menopausal status at breast cancer diagnosis.ResultsAt diagnosis, 877 women were premenopausal and 4289 were postmenopausal. Extended LET was significantly better than placebo (PLAC) in DFS for premenopausal [hazard ratio (HR) = 0.26, 95% confidence interval (CI) 0.13–0.55; P = 0.0003] and postmenopausal women (HR = 0.67; 95% CI 0.51–0.89; P = 0.006), with greater DFS benefit in those premenopausal (interaction P = 0.03). In adjusted post-unblinding analysis, those who switched from PLAC to LET improved DDFS in premenopausal (HR = 0.15; 95% CI 0.03–0.79; P = 0.02) and postmenopausal women (HR = 0.45; 95% CI 0.22–0.94; P = 0.03).ConclusionsExtended LET after 5 years of tamoxifen was effective in pre- and postmenopausal women at diagnosis, and significantly better in those premenopausal. Women premenopausal at diagnosis should be considered for extended adjuvant therapy with LET if menopausal after completing tamoxifen.