Disparities in diagnosis of advanced melanoma: a population-based cohort study.

BACKGROUND: International studies have observed inequities in stage at diagnosis of melanoma. As this has not been sufficiently studied in Canada, the purpose of this study was to investigate whether there are disparities in the diagnosis of advanced-thickness melanoma in the province of Ontario.

METHODS: In this retrospective population-based cohort study, we obtained, abstracted and linked pathology reports for a 65% random sample of all cases of invasive cutaneous melanoma in Ontario from 2007 to 2012 in the Ontario Cancer Registry. Cases without pathology reports or with unreported thickness were excluded from the primary analysis. Associations between advanced melanoma (thickness > 2.0 mm) and patient, health-system and tumour factors were described and analyzed using multivariable modified Poisson regression.

RESULTS: In total, 8042 patients had histologically confirmed melanoma and thickness information. Of these, 46.7% ( n = 3755) were female, the median age at diagnosis was 62 years and 25.7% ( n = 2069) had advanced melanoma. In multivariate analyses, advanced age (relative risk [RR] 1.53; 95% confidence interval [CI] 1.37-1.72), male sex (RR 1.12, 95% CI 1.05-1.20), lowest socioeconomic status quintile (RR 1.24; 95% CI 1.12-1.38) and health region (RR range 0.92-1.34, p = 0.005 for variable) were significantly associated with advanced melanoma. Presence of ulceration significantly modified many of these associations.

INTERPRETATION: Disparate rates of advanced melanoma according to patient and health system factors suggest there may be inequitable access to timely diagnosis of melanoma in Ontario. This highlights a potential opportunity for system improvement to ensure timely and equitable access to melanoma care.