Overview of Basal Cell Carcinoma

Jennifer Atlas, MD: Hello, and welcome to this OncLive® Inside the Clinic program titled “Basal Cell Carcinoma Treatment Advances.” I’m Dr Jennifer Atlas. I’m a medical oncologist practicing at Atrium Health Levine Cancer Institute [in Charlotte, North Carolina]. Joining me is my colleague Dr Shahab Babakoohi, who is an oncologist and dermatologist here at Levine Cancer Institute. Welcome, and thank you for joining me.

We’re going to discuss advances in the treatment of patients with basal cell carcinoma. We’ll present clinical scenarios and discuss our treatment approaches to illustrate how we incorporate data into practice to manage patients with basal cell carcinoma at our institution. Let’s get started on our first topic.

Dr Babakoohi, could you please describe the incidence patterns and patient characteristics of basal cell carcinoma?

Shahab Babakoohi, MD: Thanks for having me. Basal cell carcinoma is the most common skin cancer in United States, with nearly 3 million cases reported every year. The common risk factors for skin cancer are older age and history of sun exposure. These are the main risk factors we see in basal cell carcinoma. For the histopathology, there are different subtypes of basal cell carcinoma. Superficial and nodular subtypes are very common, and they are fortunately minimally aggressive compared with the others. Infiltrative morphea form or basal squamous subtypes are at higher risk of recurrence. Local invasion needs more attention.

Jennifer Atlas, MD: From a medical oncology standpoint, I’m predominantly seeing the higher-risk forms of basal cell carcinoma, which is the infiltrative pattern in basal squamous carcinomas. It’s interesting because nonmelanoma skin cancers make up 80% of what we see, but only a small fraction reach a medical oncologist or a multidisciplinary team. Tell me about the testing and diagnosis that goes into treating basal cell carcinoma.

Shahab Babakoohi, MD: The diagnosis, almost all the time, is made by skin biopsy. Fortunately, skin biopsy is an easy procedure because skin is easily accessible, and it’s done on an outpatient basis. It takes a few minutes to do a skin biopsy. The risks are very minimal. Most of the time, histopathology is typical under a microscope. Other neuropathologist colleagues make the diagnosis very straightforward. Occasionally there’s some overlap with features of other tumors or invasive squamous subtypes. Sometimes they do special staining. But most of the time, pathology is the way to go. In cases when we have advanced basal cell carcinoma after a pathology diagnosis, patient is referred to a multidisciplinary group, including medical oncologists. Sometimes they need to do further tests, including imaging or other further evaluations, to see the extent of the disease. This happens when they come to you.

Jennifer Atlas, MD: Let’s talk about how we risk stratify and categorize low-risk vs high-risk basal cell carcinomas. I wanted to start by talking about the NCCN [National Comprehensive Cancer Network] Guidelines, as well as our institution’s take on how we risk stratify these patients. When we think of low-risk basal cell carcinoma, we’re thinking of primary lesions. Typically, when we’re looking at locations, we’re talking about lesions that are under 2 cm when they’re present on the trunk or extremities and lesions on the face and other high-risk areas like the tibial that are less than 1 cm in size. We’re looking at lesions that are well defined. There’s typically no carry neural or vascular invasion. These aren’t immunosuppressed patients.

Conversely, looking at high-risk patients, we’re talking about patients with ill-defined borders. They are locally advanced tumors greater than 2 cm on the trunk and in extremity and in high-risk areas on the face, genital area, and pretibial, especially if they’re greater than 1 cm in those locations. These may be in patients who are immunosuppressed. For instance, we think about our solid organ transplant patients and our patients who maybe have autoimmune disease or other malignancies, especially hematologic malignancies that may have suppressed their immune system. We’re also thinking about patients who may have perineural invasion or vascular involvement as high-risk features and, as Dr Babakoohi described earlier, some high-risk pathologic features such as basal squamous cell carcinoma and infiltrative pattern of disease. Dr Babakoohi, can you think of any additional risk factors that help you stratify between low-risk and high-risk lesions?

Shahab Babakoohi, MD: You pretty much covered it. Pathology, infiltrative, and basal squamous and morpheaform basal cell carcinoma is also sometimes tricky because morphea form can show itself like an old scar on face and be undiagnosed for years. Eventually, a dermatologist takes a sample and realizes that this is morpheaform basal cell carcinoma. That’s very important because if that lesion is sitting there for years, the possibility of having more extensive disease is higher. These are the cases that, during most micrographic surgery, they realize that the extension of the disease is more than what they thought because of the chronicity of the disease.

Jennifer Atlas, MD: I’ll also add to the high-risk category patients who are having recurrent lesions or lesions in sites where they have previously had surgery or radiation. Those can be certainly more challenging in high-risk cases.

Transcript edited for clarity.