Understanding the impact of sex and stage differences on melanoma cancer patient survival: a SEER-based study

Abstract

Background: This paper investigates the difference in survival of melanoma patients across stage and sex by utilising net survival measures. Metrics are presented at both the individual and population level.

Methods: Flexible parametric models were fitted to estimate life-expectancy metrics to be applied to a group of 104,938 subjects with a melanoma skin cancer diagnosis from 2000 to 2017. Period analysis was used for better predictions for newly diagnosed patients, and missing-stage information was imputed for 9918 patients. Female relative survival was assigned to male subjects to demonstrate the survival discrepancies experienced between sexes.

Results: At the age of 60, males diagnosed at the regional stage lose an average of 4.99 years of life compared to the general population, and females lose 4.79 years, demonstrating the sex variation in expected mortality. In 2017, males contributed 3545 more life years lost than females, and a potential 1931 life years could be preserved if sex differences in survival were eliminated.

Conclusions: This study demonstrates the survival differences across population subgroups as a result of a melanoma cancer diagnosis. Females experience better prognosis across age and stage at diagnosis; however, further investigation is necessary to better understand the mechanisms behind this difference.

Fig. 1. Stage-specific 1- and 5-year relative survival curves as a function of age at diagnosis.

Top-left: Male 1-Year relative survival; top-right: Female 1-Year relative survival; bottom-left: Male 5-Year relative survival; bottom-right: Female 5-Year relative survival.

Fig. 2. Comparison of life expectancy between stage of diagnosis in cancer patients and the general population across age at diagnosis and sex.

Loss in expectation of life in comparison to general population covariate-matched subject stratified by sex and stage at diagnosis across a range of age at diagnosis.

Fig. 3. Total life years lost for melanoma skin cancer patients diagnosed in 2017, stratified by sex and stage at diagnosis, and adjustment for potential gain in life years were males to experience the same relative survival as females.

Number of cases, total life years lost and average life years lost per case are presented for each stage/sex combination.

Fig. 4. Loss in Expectation of Life if sex differences in survival are eliminated.

Stage-specific LEL of males compared with stage-specific LEL of males when assigned female relative survival.