Nodular melanoma: A distinct clinical entity and the largest contributor to melanoma deaths in Victoria, Australia

Background: There is a growing body of evidence that nodular melanoma (NM), because of its association with increased growth rate and thickness at diagnosis, accounts for a substantial proportion of melanoma deaths. Objective: We sought to assess the contribution of NM to melanoma deaths in comparison with other tumor subtypes. Methods: Four cohorts were established comprising 5775 cases of invasive primary cutaneous melanoma reported to the Victorian Cancer Registry during 1989, 1994, 1999, and 2004. Original pathology reports were reviewed. Age-standardized melanoma incidence rates were compared from 1989 to 2004 with annual percentage change using Poisson regression. Results: The incidence of thick tumors ([4 mm) increased by 3.8% (95% confidence interval 1.4 to 6.2) and 2.5% (95% confidence interval -0.5 to 5.5) per year for male and female patients, respectively. The median thickness of NM at diagnosis was 2.6 mm compared with 0.6 mm for superficial spreading melanoma. A third of patients who died from melanoma during the follow-up period had thick tumors ([4 mm), most of which were nodular subtype (61%). NM accounted for 14% of invasive melanomas, but was responsible for 43% of melanoma deaths in a total of 57,461 person-years of follow-up. By comparison, superficial spreading melanoma contributed 56% of invasive melanoma but only 30% of deaths. Limitations: Pathology review was limited to reports only. Mortality information relied mostly on death certificate information. Conclusion: The incidence of thick melanomas continues to increase. Nodular melanoma is clinically distinct and the predominant contributor to melanoma-related deaths, representing a public health challenge in reducing skin cancer mortality. (J Am Acad Dermatol 2013;68:568-75.)