The new seventh edition American Joint Committee on Cancer staging of cutaneous non-melanoma skin cancer: a critical review.

The seventh edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual includes a major revision of the staging protocol for cutaneous carcinomas. There are several significant improvements to the Tumor, Nodes, and Metastases (TNM) staging system, including consideration of high-risk factors within the primary T grade, a decrease in the tumor size threshold from 5 cm to 2 cm, improved stratification of patient lymph node status, as well as exclusion of Merkel cell carcinomas from the staging system for squamous cell carcinoma (SCC) and other cutaneous carcinomas. However, some important variables in cutaneous SCC were excluded from consideration. In addition, the AJCC Cancer Staging Manual makes some recommendations that will likely prove difficult to apply in clinical practice, particularly that Clark level, depth of invasion, and presence or absence of perineural invasion should be recorded for each peripheral SCC. In this review, we examine the new recommendations with an emphasis on their utility and practicality.