Sex disparities in thyroid cancer: a SEER population study

The incidence and mortality of thyroid cancer vary based on race as well as gender. Both gender thyroid cancer patients give variable clinical characteristics, such as tumor size and distant metastasis. However, sex differences in the prognosis of thyroid cancer remain controversial. Therefore, the present study explored the relationship between gender and prognosis of patients with thyroid cancer for conducive personalized treatment.

A retrospective analysis was carried out on patients with pathologically proven thyroid cancer from the Surveillance, Epidemiology, and End Results (SEER) database. The gender disparities in the prognosis of different cohorts, derived by propensity score matching were investigated using Cox proportional hazards models and Kaplan-Meier curves.

Among the studied 41,270 female and 13,188 males with thyroid cancer, gender was an independent prognostic factor for overall (OS) and cancer-specific (CSS) survival (HR =1.632, 95% CI: 1.499-1.777, P<0.001; HR =1.473, 95% CI: 1.245-1.741, P<0.001). Though, male patients had a larger tumor size (17.4 vs. 23.5 cm) and a larger proportion of metastasis [lymph nodes (LNs): 33.2% vs. 21.0%; distant: 2.3% vs. 0.9%], female had a higher incidence and earlier age diagnosis with thyroid cancer (48.0 vs. 52.5 years old). Survival Time (in months) of male patients was also significantly lower than female patients (72.4 vs. 76.8 months). In the Kaplan-Meier curves of cohorts derived by propensity score matching, OS and CSS declined much sharply for male (P<0.001). The mean number (2.0 vs. 4.0) and mean ratio (0.192 vs. 0.297) of positive nodes supported worse prognosis for male patients. Whereas factors including race, age, surgery, histology recodes, T, N, M stage and combined summary stage affected the CSS of male and female patients, however plus median income had an extra impact on male population (≥$55,000 vs. <$55,000: HR =0.739, 95% CI: 0.574-0.953, P=0.020).

Our study demonstrated that male patients had a prognostic factor for poorer OS and CSS. Other factors including race, age, income, histological type, surgery, T, N, M stage influenced OS of male and female thyroid cancer patients. Interestingly, race had no impact on CSS of thyroid cancer patients, whereas median income affected only the male patients CSS.