Abstract 1963: Characterization of thyroid cancer among Hispanics in California
Authors: Hsu Robert C. , Tsai Kai-Ya , Chennapan Krithika , Wojcik Katherine Y. , Lee Alice W. , Thomas Jacob , Nieva Jorge J. , Liu Lihua 
Published: April 2023

Introduction: Thyroid cancer is the second most commonly diagnosed cancer among Hispanic women, but little research on thyroid cancer has focused on Hispanics in the U.S. As one in four Hispanics live in California (CA), our study used data from the population-based California Cancer Registry (CCR) to characterize thyroid cancer in Hispanics.

Methods: We used CCR Research File of December 2020 to identify thyroid cancer cases diagnosed from 1988-2018 among CA residents in SEER*Stat readable format along with statewide mortality data with causes of death information. We examined the case distribution by sex (male, female), age of diagnosis (0-39, 40-64, and 65+ years old), race (Hispanic, Non-Hispanic (NH) White, NH Black, and Asian Pacific Islander (API)), histology (papillary, follicular, medullary, anaplastic), TNM stage (I-IV), tumor size (T0-T4) and lymph node involvement (N0, N1), lymphovascular invasion (LVI) (yes, no), and multifocality (solitary, multifocal). Age-adjusted incidence rate (AAIR) was calculated by sex, race, and selected tumor characteristics along with average annual percent change (AAPC). Age-adjusted morality rate (AAMR) for thyroid cancer-specific cause of death was also calculated by sex and race. Multivariate cox proportional hazards regression analysis was performed to evaluate the mortality risk from all causes of death by race.

Results: 97,948 thyroid cancer cases were diagnosed, accounting for 25.5% of cases. Hispanics had the highest female predominance (80.9%) and highest percentage of patients diagnosed under 40 years of age (38.7%) among all races. Hispanic overall AAIR per 100,000 in 2018 ranked 3rd (12.8) following those of APIs (14.6) and NH whites (13.5) but had the highest AAPC from 1988-2018 at 3.8% (95% CI 2.8-4.7). Hispanics had a greater percentage of stage I at diagnosis (66.5%), but a greater percentage of large tumor sizes (T3-T4: 31.1%), nodal involvement (31.5%), LVI (16.1%), and multifocality (41.8%). Among women, Hispanics had the highest AAPC in incidence (3.7%, 95% CI 2.9-4.4), papillary thyroid cancer (3.8%, 95% CI 3-4.6), Stage IV diagnosis (3.4% 95% CI 1.2-5.7), N1 nodal stage (6.6%, 95% CI 4.5-8.7), and multifocality (4.7%, 95% CI 3.6-5.9). Hispanics had the highest AAMR (0.77 overall, 0.70 males, and 0.81 females per 100,000). Adjusting for the demographic and tumor covariates, compared to NH Whites, Hispanics had the highest mortality risk among all races (hazard ratio: 1.32, 95% CI: 1.29-1.34) and seen among both sexes.

Conclusion: Hispanic thyroid cancer patients in CA had a greater proportion of larger tumor size, nodal involvement, LVI, and multifocal disease at diagnosis. Hispanics had the highest overall AAPC in incidence with Hispanic women having the highest AAPC in numerous disease characteristics. Hispanics also had the highest AAMR and mortality risk. These findings warrant further investigation of possible biological and socioeconomic factors involved.

Citation Format: Robert C. Hsu, Kai-Ya Tsai, Krithika Chennapan, Katherine Y. Wojcik, Alice W. Lee, Jacob Thomas, Jorge J. Nieva, Lihua Liu. Characterization of thyroid cancer among Hispanics in California [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1963.