Brigham and Women's Hospital tumor classification system for basal cell carcinoma identifies patients with risk of metastasis and death

Background: Despite approximately 4400 locally advanced US cases annually, high-stage basal cell carcinoma (BCC) is ill-defined. Objective: To develop a tumor (T) staging system for BCC that will predict metastasis/death and compare its performance with that of the American Joint Committee on Cancer 8th edition (AJCC8) T-staging system. Methods: Brigham and Women's Hospital (BWH) T staging was developed from a previously published nested cohort of 488 primary BCCs. Tumors were staged via BWH and AJCC8 T-staging systems, and predictions of metastasis and/or death were compared. Results: The BWH and AJCC8 T-staging systems both captured all metastases/deaths in high T stages (BWH, T2; AJCC8, T3/T4). BWH T2 included 54% fewer cases >= 2 cm than AJCC8 T3/T4. BWH had a higher specificity (0.92 vs 0.80; P<.001) and positive predictive value (24% vs 11%, P<.001) for identifying cases at risk for metastasis/death, and the C-statistic was superior for BWH (P<.001). The BWH T2 10-year cumulative incidence of metastasis/death was 37% (95% confidence interval, 21%-60%). Conclusions: BWH and AJCC 8 BCC staging both capture all metastases and deaths in the upper stages. However, BWH staging does so in half the number of cases, thus minimizing inappropriate up-staging. The risk of metastasis or death in BWH T2 BCC is sufficient to warrant surveillance for recurrence and clinical trials of adjuvant therapy.

Automated summary

The newly developed BWH staging system showed higher accuracy in identifying cases at risk for metastasis/death and minimized inappropriate up-staging in half the cases compared to AJCC 8 staging system. The 10-year cumulative incidence of metastasis/death in BWH T2 BCC was 37%, indicating the need for surveillance for recurrence and clinical trials of adjuvant therapy.