The Relationship of Body Mass Index to Reproductive Factors in Pre- and Postmenopausal African-American Women With and Without Breast Cancer

To date, there are virtually no existing data on the relationship between obesity, menopausal status, and breast cancer in African-Americans. Therefore, the present study was designed to test the following hypotheses in an African-American population: (1) there exists a positive association between BMI and breast cancer among postmenopausal women; (2) there exists an inverse association between BMI and breast cancer among premenopausal women; and (3) similar associations between BMI and reproductive factors exist for both pre- and postmenopausal breast cancer cases. The study population comprised 357 African-American women (n=193 breast cancer cases; n=164 controls). No significant differences were observed between premenopausal cases and controls for BMI, obesity categories, and reproductive factors. Among the postmenopausal women, the cases had significantly lower weight and BMI levels than the controls. Age at first pregnancy and parity were significantly lower among postmenopausal cases than their controls. No significant associations were revealed between body mass index and breast cancer for pre- and postmenopausal women. In the present study, early age at menarche was the only reproductive factor that was an independent predictor of BMI for both pre- and postmenopausal women, irrespective of breast cancer status. Also, these findings strongly suggest the need to consider reproductive factors, particularly age at menarche, as a covariate of BMI and other obesity-related diseases.     

Variability in the Practice of Fertility Preservation for Patients with Cancer

Fertility is important to women and men with cancer. While options for fertility preservation (FP) are available, knowledge regarding the medical application of FP is lacking. Therefore we examined FP practices for cancer patients among reproductive endocrinologists (REs). A 36 item survey was sent to board-certified REs. 98% of respondents reported counseling women with cancer about FP options. Oocyte and embryo cryopreservation were universally offered by these providers, but variability was noted in reported management of these cases—particularly for women with breast cancer. 86% of the respondents reported using letrozole during controlled ovarian stimulation (COS) in patients with estrogen receptor positive (ER+) breast cancer to minimize patient exposure to estrogen. 49% of respondents who reported using letrozole in COS for patients with ER+ breast cancer reported that they would also use letrozole in COS for women with ER negative breast cancer. Variability was also noted in the management of FP for men with cancer. 83% of participants reported counseling men about sperm banking with 22% recommending against banking for men previously exposed to chemotherapy. Overall, 79% of respondents reported knowledge of American Society for Clinical Oncology FP guidelines—knowledge that was associated with providers offering gonadal tissue cryopreservation (RR 1.82, 95% CI 1.14–2.90). These findings demonstrate that RE management of FP in cancer patients varies. Although some variability may be dictated by local resources, standardization of FP practices and communication with treating oncologists may help ensure consistent recommendations and outcomes for patients seeking FP.     

Comparison of Clinicopathological Features and Treatments between Young (≤40 Years) and Older (>40 Years) Female Breast Cancer Patients in West China: A Retrospective,Epidemiological, Multicenter,Case Only Study

The incidence of young cases of breast cancer is higher in China compared to the western world. We aimed to explore differences in risk factors, clinicopathological features and treatment modes of young female breast cancer compared to older patients in West China. We collected clinical information from 12,209 female breast cancer patients in West China, including risk factors, clinicopathological features and treatment modes, from January 2010 to December 2012. Chi-square tests and the multivariate logistic regression analysis were applied for statistical analysis. There were 2,682 young (≤40 years) cases and 9,527 older cases at the time of breast cancer diagnosis. Young patients had a greater tumor diameter at diagnosis, and a higher probability of axillary lymph node and distant metastasis (P < 0.05). The progesterone receptor positive expression rate, estrogen receptor/progesterone receptor double positive expression rate, and human epidermal growth factor receptor 2 (HER2) negative expression rate was higher in young patients compared to older patients (P < 0.05). For young patients, the age at menarche was earlier, they had lower marriage rates, fewer pregnancies and births, and a lower breastfeeding rate (P < 0.05). A higher proportion of young patients underwent advanced operations, neoadjuvant and adjuvant chemotherapy, radiotherapy, and endocrine therapy compared to older patients (P < 0.05). We found significant differences in the clinicopathological features, risk factors and treatment modes between young (≤40 years) and older (>40 years) female breast cancer patients in West China. As some of these results differ from those found in the western female population, it is likely that the mechanism of tumorigenesis of young female breast cancer patients in West China may differ from that in western developed countries. Further investigation into the regional differences in breast cancer tumorigenesis is warranted.     

Parity and breast cancer: evidence of a dual effect.

Epidemiological studies have shown that early first pregnancy reduces the risk of developing breast cancer, which indicates that initiation of the disease occurs at an early age. Thus the subclinical lesion of breast cancer might already be present in the breast before childbearing begins and the growth of any such focus might be modified by the endocrine changes of pregnancy. To test this hypothesis the relation between parity and age at presentation was studied in 341 unselected patients with breast cancer presenting to a single clinic. The mean age at presentation was 5.2 years lower in parous than nulliparous women (p < 0.001) and fell with increasing parity. It is concluded that reproductive history influences not only the risk of breast cancer but also the latent interval of a proportion of breast carcinomas.     

Hormonal aspects in the causation of human breast cancer: epidemiological hypotheses reviewed, with special reference to nutritional status and first pregnancy

Epidemiology of breast cancer has identified early age at menarche, late first pregnancy, low parity and late menopause as risk factors, but in addition genetic factors, height, weight and living in western countries play a significant role. The international variation in incidence is almost exclusively due to non-genetic factors. Hypotheses in prevention-oriented research are reviewed: 1. obesity-related oestrogen production as a stimulus of the tumour in postmenopausal women; 2. nutritional status and energy expenditure during puberty and adolescence, developed for fertility and fecundity and extended later to breast cancer; 3. reproductive life during early adulthood, age at first pregnancy and its specific effects on breast tissues. The message of preventability of breast cancer is that mammary epithelial differentiation should come early. Our insight concerning events in puberty and early adulthood can be consolidated in one concept on the risk of extended proliferation of breast epithelium during early adulthood in the absence of full differentiation induced by pregnancy. The combined effects of Western-type nutrition, lack of exercise and Western-type women's emancipation sets the stage for breast cancer already at a young age. Since it is unlikely that emancipated women in affluent societies will return to the original life-style of getting pregnant as soon as it is biologically possible, a novel daring way of protection has to be considered. Could a "Breast Differentiation Pill" be developed to offer protection?     

An “elite hacker”: Breast tumors exploit the normal microenvironment program to instruct their progression and biological diversity

The year 2011 marked the 40 year anniversary of Richard Nixon signing the National Cancer Act, thus declaring the beginning of the “War on Cancer” in the United States. Whereas we have made tremendous progress toward understanding the genetics of tumors in the past four decades, and in developing enabling technology to dissect the molecular underpinnings of cancer at unprecedented resolution, it is only recently that the important role of the stromal microenvironment has been studied in detail. Cancer is a tissue-specific disease, and it is becoming clear that much of what we know about breast cancer progression parallels the biology of the normal breast differentiation, of which there is still much to learn. In particular, the normal breast and breast tumors share molecular, cellular, systemic and microenvironmental influences necessary for their progression. It is therefore enticing to consider a tumor to be a “rogue hacker”—one who exploits the weaknesses of a normal program for personal benefit. Understanding normal mammary gland biology and its “security vulnerabilities” may thus leave us better equipped to target breast cancer. In this review, we will provide a brief overview of the heterotypic cellular and molecular interactions within the microenvironment of the developing mammary gland that are necessary for functional differentiation, provide evidence suggesting that similar biology—albeit imbalanced and exaggerated—is observed in breast cancer progression particularly during the transition from carcinoma in situ to invasive disease. Lastly we will present evidence suggesting that the multigene signatures currently used to model cancer heterogeneity and clinical outcome largely reflect signaling from a heterogeneous microenvironment—a recurring theme that could potentially be exploited therapeutically.     

Case-control study of fetal microchimerism and breast cancer

Background

Prior pregnancy is known to protect against development of breast cancer. Recent studies have demonstrated that pregnancy has the capacity to establish small numbers of immunologically active fetal-derived cells in the mother, a phenomenon known as fetal microchimerism (FMc). We asked whether presence of FMc, routinely acquired during pregnancy, is a protective factor for breast cancer.

Methodology/Principal Findings

DNA extracts from peripheral blood specimens were obtained from a population-based case-control study of risk factors for breast cancer in women 21 to 45 years old. Specimens were tested with quantitative PCR for presence and concentrations of male DNA presumed to derive from prior pregnancies with a male fetus. Odds ratios (OR) and 95% confidence intervals (CI) were estimated with consideration of multiple established reproductive and environmental risk factors for breast cancer. FMc results were generated on 99 parous women, 54 with primary invasive breast cancer and 45 general population controls. FMc prevalence was 56% (25/45) and 26% (14/54) in controls and cases, respectively. Women harboring FMc were less likely to have had breast cancer (OR = 0.29, 95% CI 0.11–0.83; p = 0.02, adjusting for age, number of children, birth of a son, history of miscarriage, and total DNA tested). In addition, FMc concentrations were higher in controls versus cases (p = 0.01). Median concentrations were 2 (0–78) and 0 (0–374) fetal genomes/10⁶ maternal genomes in controls and cases, respectively.

Conclusions

Results suggest that the enigma of why some parous women are not afforded protection from breast cancer by pregnancy might in part be explained by differences in FMc. Mechanistic studies of FMc-derived protection against breast cancer are warranted.     

Tumor Subtype-Specific Associations of Hormone-Related Reproductive Factors on Breast Cancer Survival

Purpose

It is inconclusive whether reproductive factors, which are known as risk factors of breast cancer, also influence survival. We investigated overall and subtype-specific associations between reproductive factors and breast cancer survival.

Methods

Among 3,430 incident breast cancer patients who enrolled in the Seoul Breast Cancer Study, 269 patients (7.8%) died and 528 patients (15.4%) recurred. The overall and subtype-specific associations of reproductive factors including age at menarche and menopause, duration of estrogen exposure, menstrual cycle, parity, age at first full-term pregnancy, number of children, age at last birth, time since the last birth, and duration of breastfeeding, on overall and disease-free survival (OS and DFS) were estimated by hazard ratios (HRs) and 95% confidence intervals (95% CIs) using a multivariate Cox proportional hazard model.

Results

An older age at menarche (HR for OS=1.10, 95% CI=1.03-1.19), a greater number of children (≥4 vs. 2, HR for DFS=1.58, 95% CI=1.11-2.26), and a shorter time since last birth (<5 vs. ≥20 years, HR for DFS=1.67, 95% CI=1.07-2.62) were associated with worse survival while longer duration of estrogen exposure with better survival (HR for DFS=0.97, 95% CI=0.96-0.99). In the stratified analyses by subtypes, those associations were more pronounced among women with hormone receptor and human epidermal growth factor 2 positive (HR+ HER2+) tumors.

Conclusions

It is suggested that reproductive factors, specifically age at menarche, number of children, time since last birth, and duration of estrogen exposure, could influence breast tumor progression, especially in the HR+ HER2+ subtype.     

Alternating Reducing and Enhancing Effect of Pregnancy on Breast Cancer Risk May Reveal Periodic Phenomena which Mask Circannual Rhythms

Although a relationship between reproductive factors and breast cancer risk has been known for long, there are many contradictions between different studies, and a connection with a biological mechanism has not yet been found. Recently, new details have been revealed about different effects of pregnancy on breast cancer risk. During pregnancy breast cancer risk is strongly reduced, while inversely,some years after giving birth the risk is increased. Furthermore, risk is strongly reduced in women whose consecutive births of four or more children occur after short intervals and are terminated before the age of 30. Recently, we have postulated rhythmicity in the occurrence of breast cancer in a subgroup of young women. By analogy with circadian rhythms it may be assumed that circannual rhythms too are influenced by synchronizers and masking effects. In circadian rhythms masking may be by external or internal periodic factors, such as the sleep/wake cycle, meal timing and activity. Over the year pregnancy may be such a periodic factor, with alternation of an empty uterus and one wich gradually enlarges as a consequence of a developing fetus. A masking factor is active only as long as present. Therefore the circannual rhythmicity of breast cancer is attenuated or nullified only during pregnancy. After giving birth, the temporal deficit of the rhythmic increase of tumor growth may be restored, leading to a rebound effect expressed as an increased clinical detection of malignancy some years later. When several consecutive pregnancies occur after short intervals the masking effect continues uninterruptedly, accompanied by a strong reduced breast cancer risk. The same biological mechanism may underly the remission during pregnancy in autoimmune disorders such as rheumatoid arthritis and Graves’ disease. The immune system, crucial in autoimmune disorders, is build up of several constituents which are clearly rhythmic, e.g the lymphocytes. Masking of one or more of these rhythmicities may lead to disease attenuation, followed by relapses as soon as the masking factor has been eliminated.     

Alternating Reducing and Enhancing Effect of Pregnancy on Breast Cancer Risk May Reveal Periodic Phenomena which Mask Circannual Rhythms

Although a relationship between reproductive factors and breast cancer risk has been known for long, there are many contradictions between different studies, and a connection with a biological mechanism has not yet been found. Recently, new details have been revealed about different effects of pregnancy on breast cancer risk. During pregnancy breast cancer risk is strongly reduced, while inversely,some years after giving birth the risk is increased. Furthermore, risk is strongly reduced in women whose consecutive births of four or more children occur after short intervals and are terminated before the age of 30. Recently, we have postulated rhythmicity in the occurrence of breast cancer in a subgroup of young women. By analogy with circadian rhythms it may be assumed that circannual rhythms too are influenced by synchronizers and masking effects. In circadian rhythms masking may be by external or internal periodic factors, such as the sleep/wake cycle, meal timing and activity. Over the year pregnancy may be such a periodic factor, with alternation of an empty uterus and one wich gradually enlarges as a consequence of a developing fetus. A masking factor is active only as long as present. Therefore the circannual rhythmicity of breast cancer is attenuated or nullified only during pregnancy. After giving birth, the temporal deficit of the rhythmic increase of tumor growth may be restored, leading to a rebound effect expressed as an increased clinical detection of malignancy some years later. When several consecutive pregnancies occur after short intervals the masking effect continues uninterruptedly, accompanied by a strong reduced breast cancer risk. The same biological mechanism may underly the remission during pregnancy in autoimmune disorders such as rheumatoid arthritis and Graves' disease. The immune system, crucial in autoimmune disorders, is build up of several constituents which are clearly rhythmic, e.g the lymphocytes. Masking of one or more of these rhythmicities may lead to disease attenuation, followed by relapses as soon as the masking factor has been eliminated.     

Exposure to Bovine Leukemia Virus Is Associated with Breast Cancer: A Case-Control Study

Background

Age, reproductive history, hormones, genetics, and lifestyle are known risk factors for breast cancer, but the agents that initiate cellular changes from normal to malignant are not understood. We previously detected bovine leukemia virus (BLV), a common oncogenic virus of cattle, in the breast epithelium of humans. The objective of this study was to determine whether the presence of BLV DNA in human mammary epithelium is associated with breast cancer.

Methods

This was a case-control study of archival formalin fixed paraffin embedded breast tissues from 239 donors, received 2002–2008 from the Cooperative Human Tissue Network. Case definition as breast cancer versus normal (women with no history of breast cancer) was established through medical records and examination of tissues by an anatomical pathologist. Breast exposure to BLV was determined by in situ-PCR detection of a biomarker, BLV DNA, localized within mammary epithelium.

Results

The frequency of BLV DNA in mammary epithelium from women with breast cancer (59%) was significantly higher than in normal controls (29%) (multiply- adjusted odds ratio = 3.07, confidence interval = 1.66–5.69, p = .0004, attributable risk = 37%). In women with premalignant breast changes the frequency of BLV DNA was intermediate (38%) between that of women with breast cancer and normal controls (p for trend < .001).

Conclusions

Among the specimens in this study, the presence of amplified BLV DNA was significantly associated with breast cancer. The odds ratio magnitude was comparable to those of well-established breast cancer risk factors related to reproductive history, hormones, and lifestyle and was exceeded only by risk factors related to genetics (familial breast cancer), high dose ionizing radiation, and age. These findings have the potential for primary and secondary prevention of breast cancer.     

Reproductive factors and breast cancer risk in Palestine: A case control study

BackgroundEarly age at menarche, late age at menopause, and late age at first full-term pregnancy are linked to a modest increase in the risk of developing breast cancer (breast ca). This study aims to investigate the reproductive determinants of breast cancer among women in the West Bank of Palestine.A structured questionnaire was used to collect data in a case-control study (237 registered cases and 237 controls). A multivariate analysis model was used to adjust for the association between women’s reproductive factors and breast ca risk. This study was approved by Al Quds University Ethical Research Committee and the Ministry of Health research unit.ResultsIn the multivariate analysis, menarche after 13 years of age, use of oral contraceptives for more than two months, and hormonal contraceptives use significantly doubled the risk for breast ca (Adjusted Odds Ratio (AOR) = 2.03, 95 % CI: 1.21–4.37, p < 0.011 and AOR = 2.2, 95 % CI: 1.24–4.01, p = 0.008, respectively). Women who used hormone replacement therapy (HRT) were significantly associated with higher odds (5 folds) of having breast ca versus those who did not use them (AOR 5.02, 95 % CI: 1.93–13.06, p = 0.001). Similarly, nulliparous women showed 6 times the odds of breast ca compared with women with one or more children (p = 0.005). Also, parental consanguinity marriage (AOR 2.59, 95 % CI: 1.53–4.36, p = 0.001) and positive family history (AOR 3.88, 95 % CI: 2.19–6.87, p = 0.001) of the condition can be strong determinants for breast ca in this study.ConclusionThis study provides clear evidence that the use of reproductive hormones, whether as a birth control tool or for therapeutic purposes, must be rationalized worldwide and in Palestine in particular.     

Reproductive health among married and unmarried mothers aged less than 18, 18–19, and 20–24 years in the United States, 2014–2019: A population-based cross-sectional study

BackgroundStudies in low- and middle-income regions suggest that child marriage (<18 years) is a risk factor for poor reproductive outcomes among women. However, in high-income-country contexts where childbearing before age 18 occurs predominantly outside marriage, it is unknown whether marriage is adversely associated with reproductive health among mothers below age 18. This study examined the joint associations of marriage and adolescent maternal age group (<18, 18–19, and 20–24 years) with reproductive, maternal, and infant health indicators in the United States.Methods and findingsBirth registrations with US resident mothers aged ≤24 years with complete information on marital status were drawn from the 2014 to 2019 Natality Public Use Files (n = 5,669,824). Odds ratios for the interaction between marital status and maternal age group were estimated using multivariable logistic regression, adjusting for covariates such as maternal race/ethnicity and nativity status, federal program participation, and paternal age. Marriage prevalence was 3.6%, 13.2%, and 34.1% among births to mothers aged <18, 18–19, and 20–24 years, respectively. Age gradients in the adjusted odds ratios (AORs) were present for most indicators, and many gradients differed by marital status. Among births to mothers aged <18 years, marriage was associated with greater adjusted odds of prior pregnancy termination (AOR 1.64, 95% CI 1.52–1.77, p < 0.001), repeat birth (AOR 2.84, 95% CI 2.68–3.00, p < 0.001), maternal smoking (AOR 1.24, 95% CI 1.15–1.35, p < 0.001), and infant morbidity (AOR 1.07, 95% CI 1.01–1.14, p = 0.03), but weaker or reverse associations existed among births to older mothers. For all maternal age groups, marriage was associated with lower adjusted odds of late or no prenatal care initiation, sexually transmitted infection, and no breastfeeding at hospital discharge, but these beneficial associations were weaker among births to mothers aged <18 and 18–19 years. Limitations of the study include its cross-sectional nature and lack of information on marriage timing relative to prior pregnancy events.ConclusionsMarriage among mothers below age 18 is associated with both adverse and favorable reproductive, maternal, and infant health indicators. Heterogeneity exists in the relationship between marriage and reproductive health across adolescent maternal age groups, suggesting girl child marriages must be examined separately from marriages at older ages.

In a population-based study, Andrée-Anne Fafard St-Germain and colleagues examine the joint associations of marriage and adolescent maternal age group (<18, 18-19, and 20-24 years) with reproductive, maternal, and infant health indicators in the United States.     

Non-Specific Factors that may influence Significance of Urinary Steroid Excretion in Breast Cancer

The urinary excretion of corticosteroids (17-oxogenic steroids) and adrenal androgens (11-deoxy-17-oxosteroids) was studied in women below the age of 50 in a variety of clinical situations for comparison with a normal group. The conditions studied were: chronic debility from non-malignant disease, weight reduction, admission to hospital and surgery for varicose veins, hepatic non-malignant disease, and non-mammary cancer.The objective of the study was to determine whether the changes found in early and advanced breast cancer and used to judge the prognosis of the disease are specific to the disease or are merely incidental to the degree of illness caused by the disease.Similar changes to those found in breast cancer—principally a reduction in the excretion of the androgens—were found in the women with severe hepatic disease and in advanced non-mammary cancer. These were also found to follow the effects of severe surgical stress.It is concluded that the changes found in breast cancer are a measure of the general systemic disturbance caused by the disease and are not due specifically to it. Nevertheless, the value of their prognostic significance remains unchallenged.     

Experimental food supplementation reveals habitat-dependent male reproductive investment in a migratory bird

Environmental factors can shape reproductive investment strategies and influence the variance in male mating success. Environmental effects on extrapair paternity have traditionally been ascribed to aspects of the social environment, such as breeding density and synchrony. However, social factors are often confounded with habitat quality and are challenging to disentangle. We used both natural variation in habitat quality and a food supplementation experiment to separate the effects of food availability—one key aspect of habitat quality—on extrapair paternity (EPP) and reproductive success in the black-throated blue warbler, Setophaga caerulescens. High natural food availability was associated with higher within-pair paternity (WPP) and fledging two broods late in the breeding season, but lower EPP. Food-supplemented males had higher WPP leading to higher reproductive success relative to controls, and when in low-quality habitat, food-supplemented males were more likely to fledge two broods but less likely to gain EPP. Our results demonstrate that food availability affects trade-offs in reproductive activities. When food constraints are reduced, males invest in WPP at the expense of EPP. These findings imply that environmental change could alter how individuals allocate their resources and affect the selective environment that drives variation in male mating success.     

Use of Sodium Butyrate as an Alternative to Dietary Fiber: Effects on the Embryonic Development and Anti-Oxidative Capacity of Rats

In this study, we evaluated the effect of replacing dietary fiber with sodium butyrate on reproductive performance and antioxidant defense in a high fat diet during pregnancy by using a rat model. Eighty virgin female Sprague Dawley rats were fed one of four diets—(1) control diet (C group), (2) high fat + high fiber diet (HF group), (3) high-fat +5% sodium butyrate diet (SB group), and (4) HF diet + α-cyano-4-hydroxy cinnamic acid (CHC group)—intraperitoneally on days 8, 10, 12, 14, and 16 of gestation. SB and dietary fiber had similar effects on improving fetal number and reducing the abortion rate; however, the anti-oxidant capacity of maternal serum, placenta, and fetus was superior in the HF group than in the SB group. In comparison, CHC injection decreased reproductive performance and antioxidant defense. Both dietary fiber (DF) and SB supplementation had a major but different effect on the expression of anti-oxidant related genes and nutrient transporters genes. In summary, our data indicate that SB and DF showed similar effect on reproductive performance, but SB cannot completely replace the DF towards with respect to redox regulation in high-fat diet; and SB might influence offspring metabolism and health differently to DF.     

Stressful life experiences and risk of relapse of breast cancer: observational cohort study

ObjectiveTo confirm, using an observational cohort design, the relation between severely stressful life experiences and relapse of breast cancer found in a previous case-control study.DesignProspective follow up for five years of a cohort of women newly diagnosed as having breast cancer, collecting data on stressful life experiences, depression, and biological prognostic factors.SettingNHS breast clinic, London; 1991-9.ParticipantsA consecutive series of women aged under 60 newly diagnosed as having a primary operable breast tumour. 202/222 (91%) eligible women participated in the first life experiences interview. 170 (77%) provided complete interview data either up to 5 years after diagnosis or to recurrence.ResultsWe controlled for biological prognostic factors (lymph node infiltration and tumour histology), and found no increased risk of recurrence in women who had had one or more severely stressful life experiences in the year before diagnosis compared with women who did not (hazard ratio 1.01, 95% confidence interval 0.58 to 1.74, P=0.99). Women who had had one or more severely stressful life experiences in the 5 years after diagnosis had a lower risk of recurrence (0.52, 0.29 to 0.95, P=0.03) than those who did not.ConclusionThese data do not confirm an earlier finding from a case-control study that severely stressful life experiences increase the risk of recurrence of breast cancer. Differences in case control and prospective methods may explain the contradictory results. We took the prospective study as the more robust, and the results suggest that women with breast cancer need not fear that stressful experiences will precipitate the return of their disease.

What is already known on this topic

Women with apparently similar tumours at the time of presentation with breast cancer differ considerably in their disease-free survival and overall survivalSuch differences in outcome may well be explained by host and environmental factors, which could include psychological and social variablesData on the relation between severely stressful life experiences and cancer progression have been contradictory

What this study adds

Women who have a severely stressful life experience in the year before being diagnosed with breast cancer, or in the five years afterwards, do not seem to be at increased risk of developing a recurrence of the diseaseWomen with breast cancer need not fear that stressful experiences will precipitate the return of their disease.     

Educational Differences in Postmenopausal Breast Cancer – Quantifying Indirect Effects through Health Behaviors,Body Mass Index and Reproductive Patterns

Studying mechanisms underlying social inequality in postmenopausal breast cancer is important in order to develop prevention strategies. Standard methods for investigating indirect effects, by comparing crude models to adjusted, are often biased. We applied a new method enabling the decomposition of the effect of educational level on breast cancer incidence into indirect effects through reproductive patterns (parity and age at first birth), body mass index and health behavior (alcohol consumption, physical inactivity, and hormone therapy use). The study was based on a pooled cohort of 6 studies from the Copenhagen area including 33,562 women (1,733 breast cancer cases) aged 50–70 years at baseline. The crude absolute rate of breast cancer was 399 cases per 100,000 person-years. A high educational level compared to low was associated with 74 (95% CI 22–125) extra breast cancer cases per 100,000 person-years at risk. Of these, 26% (95% CI 14%–69%) could be attributed to alcohol consumption. Similar effects were observed for age at first birth (32%; 95% CI 10%–257%), parity (19%; 95%CI 10%–45%), and hormone therapy use (10%; 95% CI 6%–18%). Educational level modified the effect of physical activity on breast cancer. In conclusion, this analysis suggests that a substantial number of the excess postmenopausal breast cancer events among women with a high educational level compared to a low can be attributed to differences in alcohol consumption, use of hormone therapy, and reproductive patterns. Women of high educational level may be more vulnerable to physical inactivity compared to women of low educational level.