Role of obesity on the thickness of primary cutaneous melanoma

Background: Thick primary cutaneous melanoma (PCM) is associated with older age, male sex, being single, a low educational level, self-detection and general practice detection, nodular melanoma (NM) and acral lentiginous melanoma (ALM) types; and are found in the head-neck and lower limb locations. Obesity plays a direct role on melanoma tumour growth, as it has been shown in animal models, but its role in the thickness of PCM remains unknown.

Objectives: We investigated the impact of obesity on the thickness of invasive PCM.

Methods: A cross-sectional study was performed in a prospective cohort for which we collected several clinical and histological data already known to be associated with thick PCM and the Body Mass Index from new cases of invasive PCM which were referred to the dermatology department in Valence.

Results: Four hundred and twenty-seven patients were studied. In an univariate analysis, thick PCM was associated with low educational level, obesity, identification by the patient or the general practitioner (GP), location on the cephalic extremity, in a non-visible area of the body, the NM and ALM type, and an ulceration. In a multivariate analysis, NM, ulceration, topography of the melanoma and identification of the melanoma by the patient or GP were significantly associated with thick melanoma. When including only clinical features in the model, low educational level, mode of melanoma identification and obesity were significantly associated with a risk of thick melanoma.

Conclusions: Obesity is a clinical independent risk factor of thick PCM. For health policies, governments should pay greater attention to detect melanoma in obese patients. Our results encourage the basic research on tumoural growth mechanisms due to obesity in melanoma.