Background

Overall, the incidence of papillary thyroid cancer in Hispanic women residing in the United States (US) is similar to that of non-Hispanic white women. However, little is known as to whether rates in Hispanic women vary by nativity, which may influence exposure to important risk factors.

Methods

Nativity-specific incidence rates among Hispanic women were calculated for papillary thyroid cancer using data from the California Cancer Registry (CCR) for the period 1988–2004. For the 35% of cases for whom birthplace information was not available from the CCR, nativity was statistically imputed based on age at Social Security number issuance. Population estimates were extracted based on US Census data. Incidence rate ratios (IRR) and 95% confidence intervals (CI) were also estimated.

Results

In young (age <55 years) Hispanic women, the incidence of papillary thyroid cancer among US-born (10.65 per 100,000) was significantly greater than that for foreign-born (6.67 per 100,000; IRR=1.60, 95% CI: 1.44–1.77). The opposite pattern was observed in older women. The age-specific patterns showed marked differences by nativity: among foreign-born, rates increased slowly until age 70 years, whereas, among US-born, incidence rates peaked during the reproductive years. Incidence rates increased over the study period in all subgroups.

Conclusion

Incidence rates of papillary thyroid cancer vary by nativity and age among Hispanic women residing in California. These patterns can provide insight for future etiologic investigations of modifiable risk factors for this increasingly common and understudied cancer.

Objective

To investigate how birthplace influences the incidence of papillary thyroid cancer among Asian American women.

Methods

Birthplace- and ethnic-specific age-adjusted and age-specific incidence rates were calculated using data from the California Cancer Registry for the period 1988–2004. Birthplace was statistically imputed for 30% of cases using a validated imputation method based on age at Social Security number issuance. Population estimates were obtained from the US Census. Incidence rate ratios (IRR) and 95% confidence intervals (CI) were estimated for foreign-born vs. US-born women.

Results

Age-adjusted incidence rates of papillary thyroid cancer among Filipina (13.7 per 100,000) and Vietnamese (12.7) women were more than double those of Japanese women (6.2). US-born Chinese (IRR=0.48, 95% CI: 0.40–0.59) and Filipina women (IRR=0.74, 95% CI: 0.58–0.96) had significantly higher rates than those who were foreign-born; the opposite was observed for Japanese women (IRR=1.55, 95% CI: 1.17–2.08). The age-specific patterns among all foreign-born Asian women and US-born Japanese women showed a slow steady increase in incidence until age 70. However, among US-born Asian women (except Japanese), substantially elevated incidence rates during the reproductive and menopausal years were evident.

Conclusions

Ethnic- and birthplace-variation in papillary thyroid cancer incidence can provide insight into the etiology of this increasingly common and understudied cancer.

Objective

We examined whether dietary intake of isoflavones, lignans, isothiocyanates, antioxidants, or specific foods rich in these compounds is associated with reduced risk of B-cell non-Hodgkin lymphoma (NHL), multiple myeloma (MM), or Hodgkin lymphoma (HL) in a large, prospective cohort of women.

Methods

Between 1995-1996 and December 31, 2007, among 110,215 eligible members of the California Teachers Study cohort, 536 women developed incident B-cell NHL, 104 developed MM, and 34 developed HL. Cox proportional hazards regression, with age as the time-scale, was used to estimate adjusted rate ratios (RRs) with 95% confidence intervals (CIs) for risk of lymphoid malignancies.

Results

Weak inverse associations with risk of diffuse large B-cell lymphoma were observed for isothiocyanates (RR for ≥12.1 vs. <2.7 mcM/day=0.67, 95% CI: 0.43-1.05) and an antioxidant index measuring hydroxyl radical absorbance capacity (RR for ≥2.2 vs. <0.9 μM Trolox equiv/g/day=0.68, 95% CI: 0.42-1.10; ptrend=0.08). Risk of other NHL subtypes, overall B-cell NHL, MM, or HL was not generally associated with dietary intake of isoflavones, lignans, isothiocyanates, antioxidants, or major food sources of these compounds.

Conclusions

Isoflavones, lignans, isothiocyanates, and antioxidant compounds are not associated with risk of most B-cell malignancies, but some phytocompounds may decrease risk of selected subtypes.

Objective

Although the Women’s Health Initiative trial (WHI) suggested that menopausal hormone therapy (HT) does not reduce coronary heart disease mortality overall, subsequent results have suggested that there may be a benefit in younger women. The California Teachers Cohort Study (CTS) questionnaire and mortality data was used to examine whether age modified the association between HT and the relative risk of overall mortality and ischemic heart disease (IHD) deaths.

Methods

Participants from the CTS were 71,237 postmenopausal women (mean age = 63, range 36 to 94 years) followed prospectively for mortality and other outcomes from 1995–1996 through 2004.

Results

Age at baseline was a much more important modifier of HT effects than age at start of therapy. Risks for all-cause mortality (n=8,399) were lower for younger current HT users at baseline than for never users (for women ≤60 years: HR=0.54, 95% CI=0.46–0.62). These risk reductions greatly diminished, in a roughly linear fashion, with increasing baseline age (for women 85–94 years HR=0.94, 95% CI=0.81–1.10 for all-cause mortality). Similar results were seen for IHD deaths (n=1,464). No additional significant modifying effects of age at first use, duration of use, or formulation were apparent.

Conclusions

These results provide evidence that reduced risks of mortality associated with HT use are observed among younger users but not for older postmenopausal women even those starting therapy close to their time of menopause.

Several previous studies found inverse associations between alcohol consumption and risk of non-Hodgkin lymphoma (NHL) and multiple myeloma. However, most studies were retrospective, and few distinguished former drinkers or infrequent drinkers from consistent nondrinkers. Therefore, the authors investigated whether history of alcohol drinking affected risks of NHL and multiple myeloma among 102,721 eligible women in the California Teachers Study, a prospective cohort study in which 496 women were diagnosed with B-cell NHL and 101 were diagnosed with multiple myeloma between 1995–1996 and December 31, 2007. Incidence rate ratios and 95% confidence intervals were estimated using Cox proportional hazards regression. Risk of all types of B-cell NHL combined or multiple myeloma was not associated with self-reported past consumption of alcohol, beer, wine, or liquor at ages 18–22 years, at ages 30–35 years, or during the year before baseline. NHL subtypes were inconsistently associated with alcohol intake. However, women who were former alcohol drinkers at baseline were at elevated risk of overall B-cell NHL (rate ratio = 1.46, 95% confidence interval: 1.08, 1.97) and follicular lymphoma (rate ratio = 1.81, 95% confidence interval: 1.00, 3.28). The higher risk among former drinkers emphasizes the importance of classifying both current and past alcohol consumption and suggests that factors related to quitting drinking, rather than alcohol itself, may increase B-cell NHL risk.

Objective

To investigate whether obesity and hormone therapy (HT) are associated with ovarian cancer risk among women in the California Teachers Study cohort.

Methods

Of 56,091 women age ≥45 years, 277 developed epithelial ovarian cancer between 1995 and 2007. Multivariate Cox regression was performed.

Results

Among women who never used HT, greater adult weight gain, waist circumference and waist-to-height ratio, but not adult BMI, increased risk of ovarian cancer. Compared to women who never used HT and had a stable adult weight, risk of ovarian cancer was increased in women who gained ≥40 lb (relative risk (RR) 1.8, 95% confidence interval (CI): 1.0–3.0) or used HT for >5 years (RR 2.3 95% CI: 1.3–4.1). Having both exposures (RR 1.9, 95% CI: 0.99–3.5), however, did not increase risk more than having either alone. Results were similar for waist circumference and weight-to-height ratio; however, differences across HT groups were not statistically significant.

Conclusions

This study suggests that abdominal adiposity and weight gain, but not overall obesity, increase ovarian cancer risk and that there may be a threshold level beyond which additional hormones, whether exogenous or endogenous, do not result in additional elevation in risk. However, large pooled analyses are needed to confirm these findings.

Objective

To investigate whether hormone therapy (HT) and obesity are associated with endometrial cancer risk among postmenopausal women in the California Teachers Study cohort.

Methods

Of 28,418 postmenopausal women, 395 developed type 1 endometrial cancer between 1995 and 2006. Multivariate Cox regression was performed to estimate relative risks (RR), stratified by HT use (never used, ever estrogen-alone (ET), or exclusively estrogen-plus-progestin (EPT)).

Results

Among women who never used HT, overall and abdominal adiposity were associated with increased risk; when evaluated simultaneously, abdominal adiposity was more strongly associated (RR 2.2, 95% confidence interval (CI): 1.1–4.5 for waist ≥35 vs. <35 inches). Among women who ever used ET, risk was increased in women with BMI ≥25 kg/m2 (RR 1.6, 95% CI: 1.1–2.3 vs. <25 kg/m2). Neither overall nor abdominal obesity was associated with risk in women who exclusively used EPT (P-interaction<0.001 for BMI by HT use).

Conclusions

Among women who never used HT, risk was strongly positively related to obesity and may have been influenced more by abdominal than overall adiposity; however, due to small numbers, this latter finding requires replication. Among women who ever used ET, being overweight at baseline predicted higher risk, whereas use of EPT mitigated any effect of obesity.

Objectives

We estimated trends in breast cancer incidence rates for specific Asian populations in California to determine if disparities exist by immigrant status and age.

Methods

To calculate rates by ethnicity and immigrant status, we obtained data for 1998 through 2004 cancer diagnoses from the California Cancer Registry and imputed immigrant status from Social Security Numbers for the 26% of cases with missing birthplace information. Population estimates were obtained from the 1990 and 2000 US Censuses.

Results

Breast cancer rates were higher among US- than among foreign-born Chinese (incidence rate ratio [IRR] = 1.84; 95% confidence interval [CI] = 1.72, 1.96) and Filipina women (IRR = 1.32; 95% CI=1.20, 1.44), but similar between US- and foreign-born Japanese women. US-born Chinese and Filipina women who were younger than 55 years had higher rates than did White women of the same age. Rates increased over time in most groups, as high as 4% per year among foreign-born Korean and US-born Filipina women. From 2000–2004, the rate among US-born Filipina women exceeded that of White women.

Conclusions

These findings challenge the notion that breast cancer rates are uniformly low across Asians and therefore suggest a need for increased awareness, targeted cancer control, and research to better understand underlying factors.

Nutritional status and physical activity are known to alter immune function, which may be relevant to lymphomagenesis. The authors examined body size measurements and recreational physical activity in relation to risk of B-cell non-Hodgkin lymphoma (NHL) in the prospective California Teachers Study. Between 1995 and 2007, 574 women were diagnosed with incident B-cell NHL among 121,216 eligible women aged 22–84 years at cohort entry. Multivariable-adjusted relative risks and 95% confidence intervals were estimated by fitting Cox proportional hazards models for all B-cell NHL combined and for the 3 most common subtypes: diffuse large B-cell lymphoma, follicular lymphoma, and B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma. Height was positively associated with risk of all B-cell NHLs (for >1.70 vs. 1.61–1.65 m, relative risk = 1.50, 95% confidence interval: 1.16, 1.96) and chronic lymphocytic leukemia/small lymphocytic lymphoma (relative risk = 1.93, 95% confidence interval: 1.09, 3.41). Weight and body mass index at age 18 years were positive predictors of B-cell NHL risk overall. These findings indicate that greater height, which may reflect genetics, early life immune function, infectious exposures, nutrition, or growth hormone levels, may play a role in NHL etiology. Adiposity at age 18 years may be more relevant to NHL etiology than that in later life.

Background

Early studies of incomplete pregnancy and development of breast cancer suggested that induced abortion might increase risk. Several large prospective studies, which eliminate recall bias, did not detect associations but this relationship continues to be debated.

Study design

To further inform this important question, we examined invasive breast cancer as it relates to incomplete pregnancy, including total number of induced abortions, age at first induced abortion and total number of miscarriages among women participating in the ongoing California Teachers Study (CTS) cohort. Incomplete pregnancy was self-reported on the CTS baseline questionnaire in 1995–96. Incident breast cancers were ascertained in 3,324 women through 2004 via linkage with the California Cancer Registry.

Results

Using Cox multivariable regression, we found no statistically significant association between any measure of incomplete pregnancy and breast cancer risk among nulliparous or parous women.

Conclusion

These results provide strong evidence that there is no relationship between incomplete pregnancy and breast cancer risk.

Previous studies have examined the association between individual foods or nutrients, but not overall diet, and ovarian cancer risk. To account for the clustering of foods in the diet, we investigated the association between dietary patterns and risk of ovarian cancer in the prospective California Teachers Study cohort. Of 97,292 eligible women who completed the baseline dietary assessment in 1995–1996, 311 women developed epithelial ovarian cancer on or before December 31, 2004. Based on principal components analysis, five major dietary patterns were identified and termed “plant-based,” “high-protein/high-fat,” “high-carbohydrate,” “ethnic,” and “salad-and-wine.” Multivariable Cox proportional hazards regression analysis was used to estimate associations between these dietary patterns and risk of incident ovarian cancer. Most of the dietary patterns were not significantly associated with ovarian cancer risk. However, women who followed a plant-based diet had higher risk; comparing those in the top quintile of plant-based food intake with those in the lowest quintile, the relative risk of ovarian cancer was 1.65 (95% confidence interval: 1.07–2.54; Ptrend=0.03). Associations with the five dietary patterns did not vary by known ovarian cancer risk factors or other behavioral or sociodemographic characteristics. Overall, our results show no convincing associations between dietary patterns and ovarian cancer risk.

Dietary phytochemical compounds, including isoflavones and isothiocyanates, may inhibit cancer development but have not yet been examined in prospective epidemiologic studies of ovarian cancer. The authors have investigated the association between consumption of these and other nutrients and ovarian cancer risk in a prospective cohort study. Among 97,275 eligible women in the California Teachers Study cohort who completed the baseline dietary assessment in 1995–1996, 280 women developed invasive or borderline ovarian cancer by December 31, 2003. Multivariable Cox proportional hazards regression, with age as the timescale, was used to estimate relative risks and 95% confidence intervals; all statistical tests were two sided. Intake of isoflavones was associated with lower risk of ovarian cancer. Compared with the risk for women who consumed less than 1 mg of total isoflavones per day, the relative risk of ovarian cancer associated with consumption of more than 3 mg/day was 0.56 (95% confidence interval: 0.33, 0.96). Intake of isothiocyanates or foods high in isothiocyanates was not associated with ovarian cancer risk, nor was intake of macronutrients, antioxidant vitamins, or other micronutrients. Although dietary consumption of isoflavones may be associated with decreased ovarian cancer risk, most dietary factors are unlikely to play a major role in ovarian cancer development.

Objective

Whether alcohol consumption influences ovarian cancer risk is unclear. Therefore, we investigated the association between alcohol intake at various ages and risk of ovarian cancer.

Methods

Among 90,371 eligible members of the California Teachers Study cohort who completed a baseline alcohol assessment in 1995–1996, 253 women were diagnosed with epithelial ovarian cancer by the end of 2003. Multivariate Cox proportional hazards regression analysis was performed to estimate relative risks (RRs) and 95% confidence intervals (CIs).

Results

Consumption of total alcohol, beer, or liquor in the year prior to baseline, at ages 30–35 years, or at ages 18–22 years was not associated with risk of ovarian cancer. Consumption of at least one glass per day of wine, compared to no wine, in the year before baseline was associated with increased risk of developing ovarian cancer: RR = 1.57 (95% CI 1.11–2.22), Ptrend = 0.01. The association with wine intake at baseline was particularly strong among peri-/post-menopausal women who used estrogen-only hormone therapy and women of high socioeconomic status.

Conclusions

Alcohol intake does not appear to affect ovarian cancer risk. Constituents of wine other than alcohol or, more likely, unmeasured determinants of wine drinking were associated with increased risk of ovarian cancer.