Performance of the American Joint Committee on Cancer Staging Manual, 8th Edition vs the Brigham and Women's Hospital Tumor Classification System for Cutaneous Squamous Cell Carcinoma

Abstract

Importance: Brigham and Women's tumor classification (BWH) better predicts poor outcomes than American Joint Committee on Cancer (AJCC) 7th edition (AJCC 7). AJCC 8th edition (AJCC 8) has not been evaluated. Objectives: To compare BWH and AJCC 8 tumor classifications for head and neck cutaneous squamous cell carcinoma (HNCSCC). Design, Setting, and Participants: A total of 459 patients with 680 HNCSCCs in this cohort study were staged via BWH and AJCC 8 classifications and poor outcomes (ie, local recurrence [LR], nodal metastasis [NM], disease specific death [DSD], and overall survival [OS]) were compared. The study was carried out at a single academic tertiary care center in Boston, Massachusetts. Main Outcomes and Measures: Distinctiveness (outcome differences between tumor class), homogeneity (outcome similarity within tumor class), monotonicity (outcome worsening with increasing tumor class), and C statistic. Results: A total of 680 HNCSCCs in 459 patients were included in this study, of which 313 (68%) were men with the mean (SD) age of 70.2 (12.7) years. The AJCC 8 (T3/T4) and BWH (T2b/T3) high tumor classes accounted for 121 (18%) vs 63 (9%), 17 (71%) vs 16 (70%), and 11 (85%) vs 12 (92%) of total cases, metastases, and deaths, respectively. The AJCC 8 T2 and T3 comprised 23% of cases and had statistically indistinguishable outcomes. The BWH had higher specificity (93%) and positive predictive value (30%) for identifying cases at risk for metastasis or death. C statistics showed BWH to be superior in predicting NM and DSD (P =.01 and P =.005, respectively), but there was no difference for LR and OS. Conclusions and Relevance: Lack of distinction between AJCC T2 and T3 resulted in a 23% subset of HNCSCCs with significant risk of metastasis and death - too large of a group for routine nodal staging or consideration of adjuvant therapy. The BWH identifies the same number of poor outcomes in a 9% subset of HNCSCCs, thus minimizing inappropriate upstaging of low-risk disease.