The kinetics of the visible growth of a primary melanoma reflects the tumor aggressiveness and is an independent prognostic marker: a prospective study

Abstract

Primary melanoma (MM) could be a good model to test an intuitive concept: a cancer that is growing fast in its early phase is likely to have a high aggressiveness. Since MMs are visible tumors, many patients can provide information to indirectly assess the kinetics of their lesion. A prospective study was designed to assess if the kinetics of the visible growth of a primary MM, as described by the patient, could be a noninvasive prognostic marker. The ratio of MM thickness to delay between MM appearance and MM removal was used as a surrogate value for the kinetics of the MM growth. To assess the delay between MM appearance and removal, 362 patients with self-detected invasive MM fulfilled a detailed questionnaire, which provided 2 types of estimations of this delay and thus 2 melanoma kinetics indexes (MKI and MKI*). After a median follow-up of 4 years, univariate and multivariate analyses assessed whether relapse-free survival was linked to MKI or MKI*. MKI was significantly predictive of relapse-free survival (HR = 1.84 [1.51-2.25]) and relapse at 1 year (RR = 2.93 [1.84-4.69]), independently from Breslow thickness. MKI was retained in multivariate prognostic models, just after thickness and before other usual markers. MKI* was also a significant independent risk marker, although less predictive. In this model, the initial growth kinetics of a cancer reflects its aggressiveness and a high index predicts a short-term relapse. The "subjective" data obtained from patients about their MM history, although usually neglected, can thus provide a better prognostic marker than many "objective" tests.