Skin melanoma survival is not superior in females in the new stage IIID of the 8th edition of the staging system: an analysis of data from the Surveillance, Epidemiology, and End Results (SEER) database

BACKGROUND: In the 8th edition of the melanoma staging system, stage III was divided into stages IIIA-IIID. Previous studies have found that the long-term survival rate of females is much higher than that of males. This study was designed to explore whether this sex-specific advantage still exists in the new staging subgroups. METHODS: We obtained data from individuals diagnosed with skin melanoma between 2004 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database. A total of 8,726 patients with stage III disease were enrolled in the study (5,370 males and 3,356 females). Among these patients, 505 had stage IIID disease (370 males and 135 females). RESULTS: In the 7th edition of the staging system, there were significant sex-specific differences in overall survival (OS) and melanoma-specific survival (MSS) in each subgroup of stage III. In stages IIIA–IIIC in the 8th edition, there were also significant differences between males and females (P<0.001), but in stage IIID patients, there were no significant differences in either OS (P=0.312) or MSS (P=0.288). Cox analysis confirmed that stage IIID does not affect prognosis in males. Further research found no difference between males and females with stage IIID disease in any age subgroup. CONCLUSIONS: We compared sex-specific survival differences in patients with stage III disease according to the 8th edition of the staging system. Females with stage IIIA–IIIC disease have better survival rates than males. However, among patients with stage IIID disease, there is no significant difference in survival between males and females.