Early Melanoma Nodal Positivity and Biopsy Rates before and after Implementation of the 7th Edition of the AJCC Cancer Staging Manual

Abstract

Importance: There has been a continued increase in the incidence of newly diagnosed melanomas, most of which are T1 melanomas. The associations between changes in tumor staging, implemented with the 7th edition of the AJCC Cancer Staging Manual (AJCC 7), and sentinel lymph node biopsy rates and nodal positivity rates remain to be seen. Objective: To evaluate the change that the implementation of the AJCC 7 had on staging criteria and the distribution of thin melanomas requiring nodal surgery and nodal positivity rates. Design, Setting, and Participants: Retrospective cross-sectional study from 2004 through 2013 of all adults (≥18 years) diagnosed with a T1 (Breslow depth ≤1.0 mm) melanoma using The National Cancer Database that captures 70% of all newly diagnosed cancers from accredited Commission on Cancer organizations, including both academic and community settings. Data were analyzed in May 2017. Exposures: Patients were grouped together based on year of diagnosis, before and after 2009. Main Outcomes and Measures: To determine the sentinel lymph node biopsy rate before and after the implementation of the AJCC 7. Results: A total of 141280 patients met inclusion criteria. Of 86846 patients diagnosed from 2004 through 2009, 53.7% (49644) were male and had a mean (SD) age of 57.7 (16.4) years. Of 54434 patients diagnosed from 2010 through 2013, 54.3% (31086) were male and had a mean (SD) age of 59.5 (15.9) years. After 2010, there was a 3.8% decrease in the number of nodal surgeries performed (32485 of 86846 patients [37.6%] vs 18379 of 54434 patients [33.8%]; P