A population-based analysis of 788 cases of yolk sac tumors: A comparison of males and females.

Yolk sac tumors (YST) are a rare and aggressive germ cell tumor. The objective of this study is to compare the patient characteristics and survival of YST in males and females. Demographic and clinicopathologic information were obtained from the Surveillance, Epidemiology, and End Results Program from 1973 to 2003. Statistical analysis was performed using Independent-sample t-test, chi(2) test, Kaplan-Meier methods and Cox proportional hazards regression. Seven hundred eighty-eight patients were identified, 451 (57%) were males and 337 (43%) were females. The mean age at diagnosis was similar in males and females. The age at diagnosis showed a bimodal distribution with an increased incidence in the first 4 years of life and during the 2nd to 4th decade of life. The most common site of the primary tumor was gonadal, namely testis 336 (42.6%) and ovary 257 (32.6%). Among the extragonadal sites, tumor site of origin differed in males and females. The 5-year survival of extragonadal YST (66%) was worse than gonadal YST (86%) (p < 0.05). The overall median survival for the cohort was 87 months. This was similar in males (81 months) and females (91 months) (p > 0.05). As the year of diagnosis progressed from 1973 to 2003, survival of both males and females with YST consistently improved. The bimodal age distribution of YST generates the hypothesis that sex steroids may play a role in selected YST. Although the overall survival in all YST patients has improved over the past few decades, the primary sites of origin differ in males and females and impact prognosis.