Abstract
BACKGROUND: Clinical guidelines for the treatment of melanoma are based largely on the behavior of thicker tumors. As a result, little is known about survival differences among patients with thinner tumors. OBJECTIVE: To investigate the variability in survival for American Joint Committee on Cancer stage T1 thin melanoma tumors, defined as tumors less than 1 mm thick at diagnosis. METHODS: This population-based series included 43,008 non-Hispanic whites in whom cutaneous melanoma was diagnosed between 2004 and 2013 from the California Cancer Registry. Survival outcomes were estimated using the Kaplan-Meier method. Cox proportional hazard models were used to estimate risk of death. RESULTS: Survival for patients with thin ulcerated tumors was comparable to that for patients with stage II tumors, who are currently treated more aggressively. At 12 months, patients with thin ulcerated tumors had approximately 6% lower survival (92.5% [95% confidence interval (CI), 90.6%-93.9%]) compared with patients with thin nonulcerated tumors (98.2% [95% CI, 98.0%-98.3%]). At 24 months, this survival difference increased (85.2% [95% CI, 82.8%-87.4%] vs 96.1% [95% CI, 95.8-96.3%] for those with thin ulcerated and thin nonulcerated tumors, respectively) and a greater than 15% survival difference was seen at 60 months. LIMITATIONS: Previous reports of cancer registry data have noted some evidence of miscoding of thin tumors. CONCLUSION: The poorer survival in patients with ulcerated tumors less than 1 mm thick implies the need for additional studies to determine potential benefits of more aggressive treatment.