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

Yassir Alaa Muhammed Hassan Shubbar CORRELATION BETWEEN DIFFERENT CLINICOPATHOLOGICAL PARAMETERS AND MOLECULAR SUBTYPES OF FEMALE BREAST CARCINOMA IN SOUTH REGION OF IRAQ

OBJECTIVE

The aim: To correlate variable clincopathological parameters with molecular subtypes of the breast carcinoma, which affect the prognosis and management of breast malignancy.

PATIENTS AND METHODS

Materials and methods: In this study a total of 511 female patients with breast carcinoma were included, ranging from 32 to 85 years of age, with 35.8% premenopausal and 64.1% being post-menopausal. The sample slides were stained immunohistochemically for estrogen receptors (ER), progesterone receptors (PR), ki67 and HER2, the tumors were graded histologically using the Nottingham criteria system.

RESULTS

Results: Most tumors (72.8%) ranged between 2 and 5 cm in size; the most common histological type of breast carcinoma (49.7%) was invasive ductal carcinoma of no special type, with grade 2 presented in 51.8% cases; most frequent stage at time of presentation was stage 3A, found in 39.9%; the most frequent molecular subtype was ER and/or PR+, Her2- with low proliferation rate ki67<14% subtype in 48.5%, and those group were more likely (statistically significant) to be older, have stage 3 breast cancer, present with tumor size between 2 and 5 cm and tend to be well differentiated histological grade (grade1), mostly with lymph node positive, and most likely have tumor type of invasive ductal carcinoma of no special type.

CONCLUSION

Conclusions: the most common histological type of breast carcinoma in Iraq south was invasive ductal carcinoma of no special type and most cases showed (ER and/or PR+, HER 2-, low ki67) as the most common molecular subtype.

Estrogen receptor-beta agonist diarylpropionitrile counteracts the estrogenic activity of estrogen receptor-alpha agonist propylpyrazole-triol in the mammary gland of ovariectomized Sprague Dawley rats

Although estrogen can bind both types of estrogen receptors, estrogen receptor-alpha (ERα) is dominant in mediating estrogenic activity in the mammary gland and uterus. Excessive estrogenic activity such as estrogen-based postmenopausal hormone replacement therapy increases the risk for breast and endometrial cancers. The adverse effect of estrogen on uterine endometrium can be opposed by progestins; however, estrogen-plus-progestin regimen imposes substantially greater risk for breast cancer than estrogen alone. In this study, we used ERα-selective agonist propylpyrazole-triol (PPT) and ERβ-selective agonist diarylpropionitrile (DPN) to activate ERα and estrogen receptor-beta (ERβ) separately in an ovariectomized rat model and determined whether PPT-activated ERα function in the mammary gland can be suppressed by DPN activated ERβ. Ovariectomized rats were randomly divided into six groups and treated with DMSO (control), DPN, PPT, PPT/DPN, PPT/Progesterone, and PPT/Progesterone/DPN, respectively. In the mammary gland, PPT but not DPN increased cell proliferation and amphiregulin gene expression; importantly, the stimulatory effect of PPT on mammary cell proliferation and amphiregulin gene expression can be suppressed by DPN. In the uterus, the effect of PPT on uterine weight and endometrial cell proliferation was not inhibited by DPN but can be inhibited by progesterone. These data provide in vivo evidence that PPT activated ERα activity in the mammary gland can be opposed by ERβ-selective agonist DPN, which may be explored for the development of better hormone replacement therapy regimen with less risk for breast cancer.

[The risk of breast cervical, endometrial and ovarian cancer in oral contraceptive users]

INTRODUCTION

Oral contraceptives, mainly combined monophasic pills, are widely used by young women who expect their physicians to prescribe them safe drugs which will not harm their health and which will simplify their life. Numerous epidemiologic studies have been performed to determine the relation between oral contraceptive use and the development of neoplasms.

BREAST CANCER

An increased incidence of breast cancer has occurred simultaneously with the growing use of oral contraceptives. The possibility of a link between the oral contraceptive use and breast cancer has led to intensive research, but studies have provided inconsistent results causing confusion among clinicians. It was noticed that the risk of breast cancer was slightly elevated in current and recent young oral contraceptives users. That finding could be influenced by a detection bias or could be due to the biologic effect of the pills. The absolute number of additional breast cancer cases will be very small because of low baseline incidence of the disease in young women. Oral contraceptives probably promote growth of the already existing cancer, they are probably promoters not initiators of breast cancer. The available data do not provide a conclusive answer that is needed.

CERVICAL CANCER

Numerous factors may influence the development of cervical cancer. The evidence suggests that current and recent oral contraceptive users have an increased risk of cervical cancer which decline after discontinuation of the application of medication. Oral contraceptives might increase the biological vulnerability of the cervix. Cervical cancer develops slowly over a long time period and can be effectivelv prevented by periodic cervical screening. Fortunately, oral contraceptives do not mask abnormal cervical citology. Conclusions regarding invasive cervical cancer and oral contraceptive use are not definitive but if there is any increased risk, it is low.

ENDOMETRIAL CANCER

In oral contraceptive users the endometrium is almost under the influence of progestin component which suppresses endometrial mitotic activity and its proliferation. Most epidemiologic studies show that oral contraceptives reduce the risk of endometrial cancer and that this protective effect exists many years after the discontinuation of medication.

OVARIAN CANCER

It has been long known that the oral contraceptive use causes protective anovulation and reduces the risk of ovarian cancer. This powerful reduction is the best demonstrated major benefit of oral contraception. This protection is especially observed in nulliparous and seems to persist for many years after the discontinuation of medication.

Prenatal and childhood environmental tobacco smoke exposure and age at menarche

Previous studies have reported mixed results regarding the association between age at menarche and environmental tobacco smoke exposure, both prenatally and during early childhood; however, few studies have had data available during both time periods. The present study examined whether exposure to prenatal tobacco smoke (PTS) via maternal smoking during pregnancy or childhood environmental tobacco smoke (ETS) was associated with age at menarche in a multi-ethnic birth cohort. With the uniquely available prospectively collected data on body size and growth at birth and in early life, we further examined whether the association between PTS and ETS exposure and age at menarche was mediated by these variables. From 2001 to 2006, we recruited 262 women born between 1959 and 1963 who were enrolled previously in a New York City site of the National Collaborative Perinatal Project. Mothers who smoked during pregnancy vs. those who did not were more likely to be White, younger, have more education and have lower birthweight babies. Daughters with heavy PTS exposure (≥ 20 cigarettes per day) had a later age at menarche (>12 years vs. ≤ 12 years), odds ratio (OR) =2.1 [95% confidence interval (CI) 0.9, 5.0] compared with daughters with no PTS. Daughters exposed to only childhood ETS had a later age at menarche, OR=2.1 [95% CI 1.0, 4.3], and those exposed to PTS and ETS combined had a statistically significant later age at menarche, OR=2.2 [95% CI 1.1, 4.6] compared with daughters with no PTS and no ETS. These results did not change after further adjustment for birthweight and postnatal growth suggesting that exposure to PTS and ETS is associated with later age at menarche even after considering possible relationships with growth.

Pubertal assessment method and baseline characteristics in a mixed longitudinal study of girls

OBJECTIVES

The objective of this study was to describe the assessment methods and maturation status for a multisite cohort of girls at baseline recruitment and at ages 7 and 8 years.

METHODS

The method for pubertal maturation staging was developed collaboratively across 3 sites. Girls at ages 6 to 8 years were recruited at 3 sites: East Harlem, New York; greater Cincinnati metropolitan area; and San Francisco Bay area, California. Baseline characteristics were obtained through interviews with caregivers and anthropometric measurements by trained examiners; breast stage 2 was defined as onset of pubertal maturation. The kappa statistic was used to evaluate agreement between master trainers and examiners. Logistic regression models were used to identify factors that are associated with pubertal maturation and linear regression models to examine factors that are associated with height velocity.

RESULTS

The baseline cohort included 1239 girls. The proportion of girls who had attained breast stage 2 varied by age, race/ethnicity, BMI percentile, and site. At 7 years, 10.4% of white, 23.4% of black non-Hispanic, and 14.9% of Hispanic girls had attained breast stage>or=2; at 8 years, 18.3%, 42.9%, and 30.9%, respectively, had attained breast stage>or=2. The prime determinant of height velocity was pubertal status.

CONCLUSIONS

In this multisite study, there was substantial agreement regarding pubertal staging between examiners across sites. The proportion of girls who had breast development at ages 7 and 8 years, particularly among white girls, is greater than that reported from studies of girls who were born 10 to 30 years earlier.

Decline in US breast cancer rates after the Women's Health Initiative: socioeconomic and racial/ethnic differentials

OBJECTIVES

We investigated whether there were socioeconomic and racial/ethnic disparities in recent reported declines in overall US breast cancer incidence rates attributed to post-2002 declines in hormone therapy use following publication of the Women's Health Initiative study.

METHODS

We analyzed 1992-2005 US breast cancer incidence data from the US Surveillance, Epidemiology and End Result (SEER) 13 Registries Database, stratified by race/ethnicity, county income level, age, and estrogen receptor (ER) status.

RESULTS

As we hypothesized, between 1992 and 2005, the temporal pattern of rising and then falling US breast cancer incidence rates occurred only among White non-Hispanic women who lived in high-income counties, were aged 50 years and older, and had ER-positive tumors. No such trends were evident--regardless of county income level, ER status, or age--among Black non-Hispanic, Asian/Pacific Islander, Hispanic, or-where numbers were sufficient to conduct meaningful analyses-American Indian/Alaska Native women.

CONCLUSIONS

The recent decline in US breast cancer incidence was not equally beneficial to all women, but instead mirrored the social patterning of hormone therapy use. Joint information on socioeconomic resources and race/ethnicity is vital for correctly understanding disease distribution, including that of breast cancer.

Circulating sex steroids and breast cancer risk in premenopausal women

Evidence from both laboratory and epidemiologic studies indicate a key role of hormones in the etiology of breast cancer. In epidemiologic studies, indirect data, including the consistent associations observed between reproductive factors and breast cancer risk, support an important contribution of hormones to risk. Recently, the associations between circulating hormones in premenopausal women and subsequent risk of breast cancer have been evaluated. To date, both positive and null associations have been observed for estrogens and inverse and null associations for progesterone with breast cancer risk. For estrogens, the relationships may vary by menstrual cycle phase (e.g., follicular versus luteal phase), although this requires confirmation. Few studies have evaluated estrogen metabolites in relation to breast cancer risk; hence, no conclusions can yet be drawn. Findings for the largely adrenal-derived dehydroepiandrosterone (DHEA) and DHEA sulfate also are inconsistent and may vary by age. However, relatively consistent positive associations have been observed between testosterone (or free testosterone) levels and breast cancer risk; these associations are of similar magnitude to those confirmed among postmenopausal women. In this review, we summarize current evidence and identify gaps and inconsistencies that need to be addressed in future studies of sex steroids and premenopausal breast cancer risk.

The breast cancer and the environment research centers: transdisciplinary research on the role of the environment in breast cancer etiology

OBJECTIVES

We introduce and describe the Breast Cancer and the Environment Research Centers (BCERC), a research network with a transdisciplinary approach to elucidating the role of environmental factors in pubertal development as a window on breast cancer etiology. We describe the organization of four national centers integrated into the BCERC network.

DATA SOURCES

Investigators use a common conceptual framework based on multiple levels of biologic, behavioral, and social organization across the life span. The approach connects basic biologic studies with rodent models and tissue culture systems, a coordinated multicenter epidemiologic cohort study of prepubertal girls, and the integration of community members of breast cancer advocates as key members of the research team to comprise the network.

DATA EXTRACTION

Relevant literature is reviewed that describes current knowledge across levels of organization. Individual research questions and hypotheses in BCERC are driven by gaps in our knowledge that are presented at genetic, metabolic, cellular, individual, and environmental (physical and social) levels.

DATA SYNTHESIS

As data collection on the cohort, animal experiments, and analyses proceed, results will be synthesized through a transdisciplinary approach.

CONCLUSION

Center investigators are addressing a large number of specific research questions related to early pubertal onset, which is an established risk factor for breast cancer. BCERC research findings aimed at the primary prevention of breast cancer will be disseminated to the scientific community and to the public by breast cancer advocates, who have been integral members of the research process from its inception.

Breast cancer prevention

We have developed a new approach for breast cancer prevention, capitalizing in the preventive effect of early first full-term pregnancy, hormonally induced differentiation and our ability to identify specific genomic signatures that allow us to predict risk reduction. Early pregnancy imprints in the breast permanent genomic changes or a 'signature' that reduces the susceptibility of this organ to cancer. At cellular level, what we have achieved is the shifting of the Stem Cell 1 population, highly susceptible to cancer, to a population of Stem Cell 2 that is refractory to carcinogenesis. In a case-control study, we have compared the gene expression profile in normal breast tissue from nulliparous and parous postmenopausal women with (case) and without (control) breast cancer. We have determined that early first full-term pregnancy induces a specific genomic signature in the postmenopausal breast that is the biomarker for the Stem cell 2. The Stem cell 2 contains specific genes controlling transcription, RNA processing, immune response, apoptosis and DNA repair. We have further detected in the plasma, using an ELISA assay, the proteins coded by the gene signature. We are developing clinical trials to demonstrate the proof of the principle that r-hCG can induce in the human breast a genomic signature of the Stem cell 2. This is a concept that challenges the currently available chemopreventive agents that need to be given for extended periods for maintaining the suppression of a specific metabolic pathway or the abrogation of the function of an organ.

Breast cancer epidemiology according to recognized breast cancer risk factors in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial Cohort

Background

Multidisciplinary attempts to understand the etiology of breast cancer are expanding to increasingly include new potential markers of disease risk. Those efforts may have maximal scientific and practical influence if new findings are placed in context of the well-understood lifestyle and reproductive risk factors or existing risk prediction models for breast cancer. We therefore evaluated known risk factors for breast cancer in a cancer screening trial that does not have breast cancer as a study endpoint but is large enough to provide numerous analytic opportunities for breast cancer.

Methods

We evaluated risk factors for breast cancer (N = 2085) among 70,575 women who were randomized in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Using Poisson regression, we calculated adjusted relative risks [RRs, with 95% confidence intervals (CIs)] for lifestyle and reproductive factors during an average of 5 years of follow-up from date of randomization.

Results

As expected, increasing age, nulliparity, positive family history of breast cancer, and use of menopausal hormone therapy were positively associated with breast cancer. Later age at menarche (16 years or older vs. < 12: RR = 0.81, 95% CI, 0.65–1.02) or menopause (55 years or older vs. < 45: RR = 1.29, 95% CI, 1.03–1.62) were less strongly associated with breast cancer than was expected. There were weak positive associations between taller height and heavier weight, and only severe obesity [body mass index (BMI; kg/m²) 35 or more vs. 18.5–24.9: RR = 1.21, 95% CI, 1.02–1.43] was statistically significantly associated with breast cancer.

Conclusion

The ongoing PLCO trial offers continued opportunities for new breast cancer investigations, but these analyses suggest that the associations between breast cancer and age at menarche, age at menopause, and obesity might be changing as the underlying demographics of these factors change.

Clinical Trials Registration

http://www.clinicaltrials.gov, NCT00002540.

Etiology of oral cancer in the young patient: is tongue cancer becoming the other cancer in women?

The recently reported increase in the incidence of oral cancer in a younger population, especially in young women, in the absence of the traditional risk factors has raised concern. Of particular interest is the increased incidence of carcinoma of the tongue, which has been suggested to be a distinct entity. Although there are conflicting data on incidence and sex distribution, studies suggest that the physiologic response to risk factors by men and women and the clinical behavior of these cancers in the younger population may be different than the normal variant. Effort is currently being made to elucidate the etiology and pathogenesis of oral cancer in the younger population.

The contribution of growth hormone to mammary neoplasia

While the effects of growth hormone (GH) on longitudinal growth are well established, the observation that GH contributes to neoplastic progression is more recent. Accumulating literature implicates GH-mediated signal transduction in the development and progression of a wide range malignancies including breast cancer. Recently autocrine human GH been demonstrated to be an orthotopically expressed oncogene for the human mammary gland. This review will highlight recent evidence linking GH and mammary carcinoma and discuss GH-antagonism as a potential therapeutic approach for treatment of breast cancer.

Primary prevention of breast cancer by hormone-induced differentiation

Breast cancer is a fatal disease whose incidence is gradually increasing in most industrialized countries and in all ethnic groups. Primary prevention is the ultimate goal for the control of this disease. The knowledge that breast cancer risk is reduced by early full-term pregnancy and that additional pregnancies increase the rate of protection has provided novel tools for designing cancer prevention strategies. The protective effect of pregnancy has been experimentally reproduced in virgin rats by treatment with the placental hormone human chorionic gonadotropin (hCG). HCG prevents the initiation and inhibits the progression of chemically induced mammary carcinomas by inducing differentiation of the mammary gland, inhibiting cell proliferation, and increasing apoptosis. It also induces the synthesis of inhibin, a tumor suppressor factor, downregulates the level of expression of the estrogen receptor alpha (ER-alpha) by methylation of CpG islands, imprinting a permanent genomic signature that characterizes the refractory condition of the mammary gland to undergo malignant transformation. The genomic signature induced by hCG is identical to that induced by pregnancy and is specific for this hormone. Comparison of the mammary gland's genomic profile of virgin Sprague-Dawley rats treated daily with hCG for 21 days with that of rats receiving 17beta-estradiol (E2) and progesterone (Pg) (E2 + Pg) revealed that in hCG-treated rats 194 genes were significantly up-modulated (> 2.5 log2-folds) (p < 0.01) and commonly expressed, whereas these genes were not expressed in the E2 + Pg group. The genomic signature induced by hCG and pregnancy included activators or repressors of transcription genes, apoptosis, growth factors, cell division control, DNA repair, tumor suppressor, and cell-surface antigen genes. Our data indicate that hCG, like pregnancy, induces permanent genomic changes that are not reproduced by steroid hormones and in addition regulates gene expression through epigenetic mechanisms that are differentiation-dependent processes, leading us to conclude that hormonally induced differentiation offers enormous promise for the primary prevention of breast cancer.

Infant temperament predicts life span in female rats that develop spontaneous tumors

In a recent study, we found that male rats that minimally explored a novel environment as infants died significantly faster than their more exploratory brothers. At death, these males had various complex pathologies, precluding identification of specific hormonal mechanisms underlying adult disease progression and mortality. To minimize the variance of disease processes at the end of life, we conducted a longitudinal study with female Sprague-Dawley rats prone to high rates of spontaneous mammary and pituitary tumors. For females that developed either mammary or pituitary tumors, those that had been neophobic (least exploratory) as infants died approximately 6 months earlier than their neophilic (most exploratory) sisters. In the case of mammary tumors, both benign and malignant, neophobic females developed palpable tumors earlier than neophilic females, whereas the interval between first palpation and death was the same for all females, indicating psychosocial regulation of early rather than later stages of the disease. Neophobic females' ovarian function aged more rapidly than their neophilic sisters. Concomitantly, they had lower corticosterone responses to restraint in late adulthood, ruling out high estrogen or corticosterone levels during senescence as causal factors in their accelerated mortality. During puberty, when mammary tissue is proliferating and differentiating, neophobic females experienced more irregular cycles with prolonged "luteal" phases, suggesting a role for prolactin, prolonged progesterone and fewer estrogen surges during this sensitive period for mammary tumor risk. Thus, we identified prolactin, estrogen, progesterone and possibly corticosterone dynamics as candidates for neuroendocrine mechanisms linking infant temperament with onset of adult neoplastic disease.