A retrospective study of sentinel lymph node biopsy for skin cancer in Japan: Comparison with breast cancer and evaluation of factors related to its use.

Background: Sentinel lymph node biopsy (SLNB) underuse has been reported for skin cancers; however, actual performance rates have not been compared. The objective of this study was to investigate the SLNB performance rate in skin cancers covered by health insurance in Japan and compare it with that in breast cancer.

Methods: This was a retrospective study of the SLNB performance rate in SLNB-eligible patients with breast or skin cancer from 2018 to 2019, utilizing a database linked to the Hospital-Based Cancer Registry and Diagnosis Procedure Combination survey. Demographic and tumor characteristics were analyzed using logistic regression.

Results: A total of 71,652 patients were included in this study. SLNB was performed in 86.4% (57,904/67,036) of the patients with breast cancer, 44.7% (694/1552) with melanomas, 3.1% (89/2849) with squamous cell carcinomas (SCCs), and 13.5% (29/215) with Merkel cell carcinomas (MCCs). The performance rate of SLNB was significantly lower for skin cancers than for breast cancers (odds ratio [OR], 0.03; p < 0.001). In addition, the performance rates of SLNB were significantly lower for SCCs and MCCs than for melanomas (SCC: OR, 0.04; p < 0.001; MCC: OR, 0.19; p < 0.001). Factors associated with SLNB performance included age, sex, year of incidence, primary tumor site, T stage, and number of hospital beds.

Conclusions: SLNB is underutilized for skin cancer. Further investigation is required to explore the reasons for its underutilization so that it may be implemented more universally.