Correlation of body mass index with female survival benefit among a single-institution cohort of cutaneous melanomas >1 mm thick following wide-local excision and sentinel lymph node biopsy.

Abstract

172 Background: As the 10-year mortality for localized cutaneous melanomas (CMMs) > 1.00 mm is 40%, non-therapeutic interventions to supplement active surveillance following resection may be beneficial. Data describing the impact of lifestyle choices on survival in this population are limited. Methods: 837 consecutive patients who underwent wide local excision and sentinel lymph node biopsy (WLE + SLNB) at Yale during 1997-2012 for CMMs > 1.00 mm thick were enrolled. Smoking, alcohol use and caffeine consumption were assessed by questionnaire at diagnosis and were each categorized according to quantity used with never-users as the reference. Body mass index (BMI) was calculated from height and weight measured at surgery. Crude and multivariable marginal relationships between lifestyle factors and disease free survival (DFS), the latter adjusted for age, sex, thickness (mm), ulceration, mitotic count, and SLN status, were assessed using Cox proportional hazards. Interactions with clinicopathologic factors were conducted. Results: A female survival benefit (HRFEMALE= 0.69; 95% CI: 0.49-0.97; p = 0.04) was observed on multivariable analysis. While BMI was not independently associated with DFS (p = 0.31), we noted a significant interaction between sex and BMI (p = 0.01). Compared with referent normal weight (BMI < 25) men, normal weight women had similar survival (HRBMI < 25= 0.91; 95% CI: 0.52-1.57, p = 0.74) but a progressive survival advantage was observed among women with increasing BMI (HROVERWT= 0.62; 95% CI: 0.33-1.14, HROBESE= 0.23; 95% CI: 0.07-0.58, ptrend= 0.01). A similar relationship was not observed among men (ptrend= 0.51). Neither the marginal effects nor those modified by sex for each of alcohol, tobacco or caffeine were associated with DFS (p > 0.15). Conclusions: Following WLE+SLNB, increasing BMI may improve survival among women but not among men. Research to identify contributory molecular mechanisms in the context of the female survival benefit is warranted.