Oncologic Outcomes for Squamous Cell Carcinoma In Situ With a Clinically Resolved Biopsy Site Managed by Watchful Waiting.

BACKGROUND:Treatment option decisions for low-risk squamous cell carcinoma in situ (SCCIS) are hampered by a paucity of management-type-specific outcomes data. OBJECTIVE:Describe SCCIS tumor outcomes managed by watchful waiting and risk factors associated with poor cancer outcomes. MATERIALS AND METHODS:Retrospective cohort study. Setting: Single academic hospital in a rural setting. Patients: Adults with SCCIS diagnosed between January 01, 2014, and December 31, 2016. Main Outcomes and Measures: Hazard ratios (HRs) for local recurrence (LR), nodal metastases (NM), distant metastases (DM), and disease-specific death (DSD). RESULTS:A total of 411 consecutive SCCIS tumors that were considered clinically resolved at follow-up and managed with watchful waiting were included. Seventeen tumors recurred locally. No instances of NM, DM, or DSD were identified. Multivariate analysis found that solid-organ transplant recipient status conferred the highest risk of local recurrence [HR, 9.979 (95% CI, 2.249-39.69)]. Additional risk factors predicting LR include anatomic location on the vermilion lip or ear [HR, 9.744 (95% CI, 1.420-69.28)], anatomic location on the head and neck [HR, 6.687 (95% CI, 1.583-36.15)], and a biopsy with tumor extending to the deep edge [HR, 6.562 (95% CI, 1.367-39.04)]. CONCLUSION:Watchful waiting for SCCIS with a clinically resolved biopsy site has a local recurrence rate of 4%.