Long-Term Survival in Young Women: Hazards and Competing Risks after Thyroid Cancer

Background. Differentiated thyroid cancers (DTCs) are one of the most common and survivable cancers diagnosed in women. We examine factors associated with long-term survival and competing risks of death in women diagnosed with DTC under the age of 40 (<40) and aged 40 and older ( ). Methods. SEER data was used to identify DTCs diagnosed in women from 1975 to 2009. We examined overall (OS), disease-specific (DSS), other cancer (OCS), and non-cancer-related (NCS) survival using multivariate Cox proportional hazards modeling. Results. Observed survival was 97.2% for <40 ( ) and 82.5% for ( ). Distant stage ( , 95% CI 1.23–3.07), non-Hispanic Black ( , 95% CI 1.45–2.87), being unmarried ( , 95% 1.03–1.54), and subsequent primary cancers ( 95% CI 3.76–5.71) were significant for OS in women <40. Age was an effect modifier for all survival outcomes. Racial disparities in NCS were most pronounced for young non-Hispanic black women ( , 95% CI 2.17–5.22). Women in both age groups were more likely to die from other causes. Conclusions. Age at diagnosis remains one of the strongest prognostic factors for thyroid cancer survival. More directed efforts to ensure effective care for comorbid conditions are needed to reduce mortality from other causes. 1. Introduction The age-adjusted incidence of female thyroid cancer from 2005 to 2009 was 17.3 per 100,000, making it the 5th leading cancer diagnosis among women according to the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) Program [1]. Recent reports estimate that thyroid cancer incidence has been increasing significantly at an average annual rate of 6.6% per year since 1998 [2]. From 2010 to 2012, 113,690 new cases of thyroid cancer are expected to be diagnosed among US women alone [3–5]. Thyroid cancer is not only one of the leading types of cancer among women; it is also one of the most survivable with current 5-year relative survival rates as high as 98% [1]. The high incidence of thyroid cancer combined with its high survival makes it one of the most prevalent cancers in the country among women, contributing an estimated 6% ( ,969) to the total female cancer prevalence as of January 1, 2009 [1]. The gender, age, race/ethnic, and histological patterns among individuals diagnosed with thyroid cancer have been studied extensively [1, 6–15]. The association of geographic location and socioeconomic status (SES) with the incidence of thyroid cancer is not well studied, but evidence suggests that incidence rates vary by SEER registry [7, 12, 13] and that individuals who live in areas with