PURPOSE: To evaluate how the association between body size and breast cancer risk varies by tumor receptor subtype, host factors, and other exposures among women in the California Teachers Study cohort. METHODS: Among 52,642 postmenopausal women, 2,321 developed invasive breast cancer with known estrogen- and progesterone-receptor status (1,652 ER+PR+, 338 ER+PR-, and 312 ER-PR-) between 1995 and 2007. In a subset of 35,529 with waist circumference data, 1,377 developed invasive breast cancer with known ERPR status (991 ER+PR+, 208 ER+PR-, 169 ER-PR-) between 1997 and 2007. Multivariate Cox regression was performed to estimate relative risks (RR) and 95% confidence intervals (CI). RESULTS: Obesity, adult weight gain of ≥40 pounds, greater abdominal adiposity, and greater height increased the risk of ER+PR+ breast cancer. The increased risk associated with postmenopausal obesity was limited to those who did not use hormone therapy (HT) at cohort entry (RR = 1.37; 95% CI, 1.05-1.78 for BMI ≥ 30 vs. < 25 kg/m(2); p-interaction = 0.14) and those who were not overweight or obese at age 18 (p-interaction = 0.06). The increased risk associated with greater abdominal adiposity was limited to those who were not also overweight or obese (p-interaction = 0.01). Neither obesity, abdominal adiposity, nor height was associated with the risk of ER-PR- tumors. CONCLUSIONS: The effects of body size on postmenopausal breast cancer risk differed by hormone receptor subtype, and among women with ER+PR+ tumors, by HT use and early adult body size.

Background

Few studies have focused on prognostic factors among adolescents and young adults (AYAs) 15 to 39 years of age when diagnosed with differentiated thyroid cancer (DTC). Our study expands upon prior work by including an evaluation of survival among AYA men and by neighborhood socioeconomic status, health insurance, and clinical factors to identify subgroups of young DTC patients at higher risk of mortality.

Methods

Data for 16,827 AYA DTC patients diagnosed between 1988 and 2010 were obtained from the California Cancer Registry. Survival, through 2010, by sociodemographic and clinical factors was analyzed using Cox proportional hazards regression.

Results

Of the 2.1% of AYAs who died, 16.7% died from thyroid cancer and 21.4% died from a subsequent cancer. In multivariate analyses, older AYAs 35 to 39 year of age (versus 15- to 29-year-olds), men (hazard ratio [HR] 2.77, 95% confidence interval [CI] 1.62-4.72), and AYAs of African American or Hispanic race/ethnicity (versus non-Hispanic whites) had worse thyroid cancer specific survival. In addition, residing in low socioeconomic status neighborhoods (HR 3.11 [CI 1.28-7.56]) and nonmetropolitan areas (HR 5.53 [CI 2.07-14.78]) was associated with worse thyroid cancer-specific survival among AYA men, but not AYA women.

Conclusions

Despite the generally good prognosis among AYAs with DTC, we identified subgroups of AYA patients at risk for poor outcomes. Further study of the factors underlying these associations, including possible barriers to receiving high-quality treatment and follow-up care, as well as lifestyle factors, are critical to reducing these disparities.

Background

Cadmium (Cd) is a developmental toxicant that is released into the environment during industrial processes. Previous animal studies suggest that Cd may impact the onset of puberty.

Objectives

To determine whether Cd exposure, measured as urinary Cd concentration, was associated with ages at menarche and pubertal development.

Methods

A cohort of 211 girls, ages 10-13 years at baseline, was followed for up to two years. Girls completed an interview and self-assessment of Tanner stages of breast development and pubic hair growth. They were followed monthly until menarche. Urinary Cd concentrations were measured in overnight urine specimens. Multivariable Cox regression was used to evaluate the association between urinary Cd and age at menarche and cumulative logit regression was used to evaluate the associations between urinary Cd and breast development and pubic hair growth.

Results

The baseline geometric mean creatinine-adjusted Cd concentration was 0.22 μg/g creatinine (geometric standard deviation = 1.6) and decreased with increasing age (p-trend = 0.04). Cd levels were higher among Asian than White girls or girls of other/mixed race/ethnicity (p = 0.04). In multivariable analyses, girls with urinary Cd ≥ 0.4 μg/L were less likely to have attained menarche than girls with urinary Cd < 0.2 μg/L (hazard ratio = 0.42; 95% confidence interval, 0.23-0.78). Urinary Cd was negatively associated with pubic hair growth (p-trend = 0.01) but not with breast development (p-trend = 0.72) at baseline.

Conclusions

These findings suggest that a higher Cd body burden may delay some aspects of pubertal development among girls.

Female steroid hormones are hypothesized to play a protective role in pancreatic cancer risk. However, results from epidemiologic studies that examined hormone-related exposures have been inconsistent. The California Teachers Study is a cohort study of female public school professionals that was established in 1995-1996. Of the 118,164 eligible study participants, 323 women were diagnosed with incident invasive pancreatic cancer through December 31, 2009. Multivariable Cox proportional hazards regression methods were used to estimate hazard ratios and 95% confidence intervals for the association of pancreatic cancer risk with reproductive factors and exogenous hormone use. Current users of estrogen-only therapy at baseline (1995-1996) had a lower risk of pancreatic cancer than did participants who had never used hormone therapy (hazard ratio = 0.59, 95% confidence interval: 0.42, 0.84). Use of estrogen-plus-progestin therapy was not associated with the risk of pancreatic cancer. A longer duration of oral contraceptive use (≥10 years of use compared with never use) was associated with an increased risk of cancer (hazard ratio = 1.72, 95% confidence interval: 1.19, 2.49). Reproductive factors, including age at menarche, parity, breastfeeding, and age at menopause, were not associated with pancreatic cancer risk. Our results suggest that increased estrogen exposure through estrogen-only therapy may reduce pancreatic cancer risk in women.

We investigated the association between hypertension, antihypertensive (AH) medication use, and breast cancer in a large prospective study, the California Teachers Study (CTS). Information on history of hypertension and lifetime regular use of AH medications was collected from 114,549 women in 1995–1996. Among them, 4,151 invasive breast cancers were diagnosed between 1995 and 2006. Additional information on AH use was collected from 73,742 women in 2000–2001, and 1,714 of these women were subsequently diagnosed with breast cancer. Cox proportional hazards regression was used to estimate relative risks (RR) and 95% confidence intervals (CI) for breast cancer. Use of AH medication for ≥5 years, when compared with no use, was associated with a modest increased risk of invasive breast cancer (RR = 1.18, 95%CI 1.02–1.36). This increased risk appeared to be confined to estrogen receptor (ER)-positive tumors (RR = 1.21, 95%CI 1.03–1.43) and pre-/peri-menopausal women (RR = 1.58, 95%CI 1.11–2.25). Increased risk of invasive breast cancer was observed for long-term (≥5 years) AH use, and this appeared to be confined to ER + breast cancer and younger women.

Introduction

Historically, the incidence rate of breast cancer among non-Hispanic white women living in the San Francisco Bay area (SFBA) of California has been among the highest in the world. Substantial declines in breast cancer incidence rates have been documented in the United States and elsewhere during recent years. In light of these reports, we examined recent changes in breast cancer incidence and risk factor prevalence among non-Hispanic white women in the SFBA and other regions of California.

Methods

Annual age-adjusted breast cancer incidence and mortality rates (1988 to 2004) were obtained from the California Cancer Registry and analyzed using Joinpoint regression. Population-based risk factor prevalences were calculated using two data sources: control subjects from four case-control studies (1989 to 1999) and the 2001 and 2003 California Health Interview Surveys.

Results

In the SFBA, incidence rates of invasive breast cancer increased 1.3% per year (95% confidence interval [CI], 0.7% to 2.0%) in 1988-1999 and decreased 3.6% per year (95% CI, 1.6% to 5.6%) in 1999-2004. In other regions of California, incidence rates of invasive breast cancer increased 0.8% per year (95% CI, 0.4% to 1.1%) in 1988-2001 and decreased 4.4% per year (95% CI, 1.4% to 7.3%) in 2001-2004. In both regions, recent (2000-2001 to 2003-2004) decreases in invasive breast cancer occurred only in women 40 years old or older and in women with all histologic subtypes and tumor sizes, hormone receptor-defined types, and all stages except distant disease. Mortality rates declined 2.2% per year (95% CI, 1.8% to 2.6%) from 1988 to 2004 in the SFBA and the rest of California. Use of estrogen-progestin hormone therapy decreased significantly from 2001 to 2003 in both regions. In 2003-2004, invasive breast cancer incidence remained higher (4.2%) in the SFBA than in the rest of California, consistent with the higher distributions of many established risk factors, including advanced education, nulliparity, late age at first birth, and alcohol consumption.

Conclusion

Ongoing surveillance of breast cancer occurrence patterns in this high-risk population informs breast cancer etiology through comparison of trends with lower-risk populations and by highlighting the importance of examining how broad migration patterns influence the geographic distribution of risk factors.

Objective

[corrected] To determine risk factor profiles and cancer incidence rates among participants in the California Teachers Study (CTS), a study designed to document high breast cancer incidence rates of California teachers and to investigate emergent hypotheses in the etiology of breast and other cancers.

Methods

The CTS is a prospective study of 133,479 California female teachers and administrators, established in 1995-1996 with members of the California State Teachers Retirement System completing a detailed mailed questionnaire regarding possible risk factors for breast and other cancers. Cancer outcomes were identified by linkage with the California Cancer Registry.

Results

CTS participants have a 51% higher age-standardized invasive breast cancer incidence rate and a 67% higher in-situ breast cancer incidence rate than would be expected based on race-specific statewide rates after three years of follow-up. CTS participants also have substantially elevated rates of endometrial cancer (rate ratio, RR = 1.72), ovarian cancer (RR = 1.28), melanoma (RR = 1.59), non-Hodgkin's lymphoma (RR= 1.53), and leukemia (RR = 1.28), but low rates of invasive cervix cancer (RR = 0.53) and lung cancer (RR = 0.66).

Conclusions

CTS members have high rates of several major cancers, particularly breast cancer, and low rates of lung and cervix cancer. Although late age at first birth can explain a portion of the observed excess risk of breast cancer in this cohort, the unique risk factor profile of CTS members may account for much of their higher risk of breast and selected other cancers. The CTS offers a rich resource for future studies of cancer risk and of women's health, in general.

Objective

To evaluate the reproductive and lifestyle correlates of a surgically confirmed diagnosis of endometriosis or adenomyosis in a large prospective cohort.

Design

Collection of surgical diagnoses of endometriosis and adenomyosis during follow-up of women with no prior history of endometriosis and no prior surgery for adenomyosis.

Setting

The California Teachers Study (CTS), an ongoing prospective study of female teachers and school administrators established from the rolls of the California State Teachers Retirement System.

Patient(s)

Women with surgical diagnoses of endometriosis and adenomyosis were identified from California statewide hospital patient discharge records for CTS cohort members with an intact uterus and no prior history of endometriosis. Women with an incident surgical diagnosis of endometriosis (n = 229) or adenomyosis (n = 961) were compared with disease-free women in the same age range (for endometriosis, n = 43,493; for adenomyosis, n = 79,495).

Intervention(s)

None.

Main outcome measure(s)

Multivariable logistic regression methods were used to calculate prevalence odds ratios and associated 95% confidence intervals for the associations between self-reported menstrual and reproductive characteristics and either endometriosis or adenomyosis.

Result(s)

Women surgically diagnosed with endometriosis were younger than those surgically diagnosed with adenomyosis. Factors statistically significantly associated with endometriosis were having a mother or sister with endometriosis and nulligravidity. Factors statistically significantly associated with adenomyosis were increasing parity, early menarche (Conclusion(s)These observations provide the first epidemiologic profile of women with a surgical diagnosis of adenomyosis and indicate that this profile differs from that of women with a surgical diagnosis of endometriosis. Our results also suggest that adenomyosis but not endometriosis is associated with increased endogenous exposure to estrogen.

Objectives

These analyses were designed to describe characteristics associated with active and passive smoking in a large cohort of women in order to identify possible confounders of the relationship between smoking exposures and breast cancer risk.

Methods

Analyses were based on 1995 data collected from the California Teachers Study (CTS) and were restricted to those with complete and usable tobacco data (n = 128,174). Age-adjusted and race-adjusted odds ratios (OR) were generated by unconditional logistic regression.

Results

Compared with never smokers, both current and former smokers experienced menarche at an earlier age. Current and former smokers also were more likely than their never smoking counterparts to be nulliparous. Among parous women, current, but not former smokers were less likely than never smokers to have had their first child at an older age. Similarly, among never smokers, those exposed to household passive smoking experienced menarche at an earlier age, were more likely to be nulliparous, and among parous women, were less likely to have had their first child at an older age than never smokers not exposed to passive smoking. Greater alcohol consumption was strongly associated with both active and passive smoking exposures. Compared with never smokers, current smokers were less likely to take antioxidant supplements, whereas former smokers were more likely to take antioxidant supplements. Among never smokers, antioxidant use did not differ depending on passive smoking exposure. A number of other dietary correlates of active and passive smoking were identified.

Conclusions

We identified a number of reproductive and dietary correlates to smoking exposures that underscore the need to adjust for such factors in an analysis of smoking and breast cancer and potentially other disease entities. Furthermore, these findings may suggest potential mechanisms underlying an association between breast cancer and smoking.