What Defines Locally Advanced BCC Beyond Tumor Size

Welcome back to another Dermatology Times Case-Based Peer Perspectives series. In "What Defines Locally Advanced BCC Beyond Tumor Size," Mohs surgeon Dr. Gaurav Singh of City of Hope Comprehensive Cancer Center, Chicago, opens the series on locally advanced basal cell carcinoma.

Dr. Singh opens with a question he hears often from patients and referring clinicians: what exactly makes basal cell carcinoma advanced? He calls it a surprisingly difficult question, even for the most common skin cancer in the United States. Roughly 5 million Americans develop basal cell carcinoma each year, and while some features of advanced disease are obvious, others are subtle.

Size is the clearest example. Tumors larger than 2 cm, or 4 cm by some standards, are often considered advanced, but Dr. Singh stresses that anatomic location changes the calculation. A 3-cm lesion on the back may carry different implications than a 5-mm lesion on the eyelid margin. Depth of invasion, typically extension beyond the subcutaneous fat, is another key feature.

He points out that basal cell carcinoma lacks a uniform staging system, unlike cutaneous squamous cell carcinoma and melanoma. Several risk factors are therefore borrowed from AJCC staging for other cancers and do not reliably predict high-risk behavior in every case. Higher-risk histologic subtypes, including morpheaform and micronodular variants, also raise concern for advanced disease.

Dr. Singh cautions against overreliance on the initial pathology report. Depending on the study and the population, about one-third of superficial basal cell carcinomas are upstaged on final pathology. A low-risk read at the surface does not exclude more advanced disease beneath it.

Patient factors matter as much as tumor factors. He describes a history of leukemia, lymphoma, or organ transplant as a signal that advanced disease may be present even when it is not clinically apparent. Recurrent tumors, tumors arising in scars, and a history of radiation, immunotherapy, or other cancers are further indications that locally advanced disease may be present.

The next episode in this series, "Why Hedgehog Inhibitors Remain Underused in Advanced BCC," features Dr. Singh explaining why oral systemic therapy is often overlooked and how surgical fatigue can reframe the treatment conversation.