Thyroid Cancer Survival in the Multiethnic Cohort Study.

OBJECTIVE: The US 5-year survival rate after thyroid cancer (TC) diagnosis is over 95%. Our aim was to investigate survival differences by sex and race and ethnicity in a multiethnic US population. DESIGN: In the Multiethnic Cohort (MEC) study, a total of 605 incident TC cases were identified by linkage to HI and CA statewide cancer registries. Cox models were performed to compare the risk of all-cause mortality among TC cases by sex and race and ethnicity, with adjustment for age, first course of treatment, baseline body mass index, smoking status, alcohol intake, and neighborhood socioeconomic status. Survival among cases was also compared to matched MEC controls with no thyroid cancer. RESULTS: After a mean follow-up of 10.1 years, 250 deaths occurred among TC cases, including 63 deaths attributed to thyroid cancer. The median survival was 14.7 years, and the 5-year age-adjusted overall survival was 84.4% for female cases and 68.7% for male cases (p < 0.0001, HR 2.28 (95% CI: 1.72, 3.01)). Age-adjusted survival was lower among African American, Native Hawaiian, and Filipino cases, compared to Japanese American cases, with Whites and Latinos being intermediate. Men and Filipinos were found to have excess mortality due to thyroid cancer compared to controls (adjusted HR 1.39, 95% CI: 1.11, 1.74; HR 1.62, 95% CI: 1.04, 2.53, respectively). CONCLUSIONS: Sex and racial and ethnic disparities in survival among TC cases were similar to those found in the general population. However, cases with TC had an excess risk of death among males and for Filipinos.

Reproductive Factors and Thyroid Cancer Risk: The Multiethnic Cohort Study.

Background: Women are three times more likely to be diagnosed with thyroid cancer than men, with incidence rates per 100,000 in the United States of 20.2 for women and 7.4 for men. Several reproductive and hormonal factors have been proposed as possible contributors to thyroid cancer risk, including age at menarche, parity, age at menopause, oral contraceptive use, surgical menopause, and menopausal hormone therapy. Our study aimed to investigate potential reproductive/hormonal factors in a multiethnic population. Methods: Risk factors for thyroid cancer were evaluated among female participants (n = 118,344) of the Multiethnic Cohort Study. The cohort was linked to Surveillance, Epidemiology, and End Results cancer incidence and statewide death certificate files in Hawaii and California, with 373 incident papillary thyroid cancer cases identified. Exposures investigated include age at menarche, parity, first pregnancy outcome, birth control use, and menopausal status and type. Multivariable Cox proportional hazards models were used to obtain relative risk (RR) of papillary thyroid cancer and their 95% confidence intervals (CI). Covariates included age, race and ethnicity, reproductive history, body size, smoking, and alcohol consumption. Results: We observed a statistically significant increased risk of papillary thyroid cancer for oophorectomy (adjusted RR 1.58, 95% CI: 1.26, 1.99), hysterectomy (adjusted RR 1.65, 95% CI: 1.33, 2.04), and surgical menopause (adjusted RR 1.55, 95% CI: 1.22, 1.97), and decreased risk for first live birth at ≤20 years of age versus nulliparity (adjusted RR 0.66, 95% CI: 0.46, 0.93). These associations did not vary by race and ethnicity (p het > 0.44). Conclusion: The reproductive risk factors for papillary thyroid cancer reported in the literature were largely confirmed in all racial and ethnic groups in our multiethnic population, which validates uniform obstetric and gynecological practice.

Breast, Colorectal and Prostate Cancer Incidence among Filipino Americans by Generational Status in the Multiethnic Cohort Study.

BACKGROUND: Filipino Americans constitute 12% and 4% of the respective populations of Hawaii and California, with a large proportion of immigrants experiencing increasing cancer rates. This study investigated the incidence of colorectal, breast, and prostate cancer by generational status in the Multiethnic Cohort (MEC). METHODS: We analyzed 10,495 Filipino MEC 1st, 2nd, and 3rd generation participants, in which 26.8% were of mixed race and ethnicity. Linkage to statewide cancer registries identified 375 breast, 249 colorectal, and 436 prostate cancer incident cases. Cox models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for the association between generational status and cancer incidence. Models were adjusted for age at cohort entry and cancer-specific covariates that were chosen based on stepwise regression. RESULTS: Compared to the 1st generation, colorectal cancer showed a significantly higher incidence in the 2nd and 3rd generations with respective HRs of 1.43 (95%CI: 1.04, 1.98) and 1.76 (95%CI: 1.29, 2.38). This association was attenuated after adjustment for relevant covariates. Breast cancer incidence was elevated in the 3rd vs. 1st generation (HR=1.29, 95%CI: 1.01, 1.63) even in the fully adjusted model, whereas little difference was observed for prostate cancer. CONCLUSIONS: In this prospective study, we found differences in incidence by generational status, specifically colorectal cancer among men and female breast cancer. IMPACT: Understanding behavioral changes due to acculturation is warranted to mitigate cancer risks in migrant populations.