Basal and Squamous Cell Skin Cancer: Patient Guide

Nonmelanoma skin cancer is the most common cancer in the United States. The National Cancer Institute (NCI) reports that about 3.3 million people were treated for it in 2012, based on Medicare data. That is more than all other new cancer cases combined in a year.

And yet NCI notes it "accounts for less than 0.1% of patient deaths caused by cancer."

Both facts are true at once. The stakes here are usually not survival. They are your nose, your eyelid, your ear, and how many procedures it takes to be done. That is what treatment choices should be judged on.

Basal cell carcinoma (BCC) is the commoner of the two. NCI describes it as "at least three times more common than SCC in nonimmunocompromised patients." BCCs "are slow growing and rarely metastasize," though they can be locally destructive if ignored.

Cutaneous squamous cell carcinoma (SCC) behaves differently. NCI states that SCCs "are more aggressive than BCCs and have a range of growth, invasive, and metastatic potential."

That difference is why the first line of your pathology report matters more than most people realize.

NCI describes these lesions plainly. "A sore that does not heal." Growths that are "raised, smooth, shiny, and look pearly." Growths that are "firm and look like a scar, and may be white, yellow, or waxy." Growths that are "raised and red or reddish-brown." Growths that are "scaly, bleeding, or crusty."

The scar-like one deserves attention, because nobody thinks a scar is a tumor.

For basal cell carcinoma, NCI describes three patterns.

Nodular is the classic one: a raised lesion with a pearly look and fine visible blood vessels called telangiectasias.

Superficial carries a lower risk of coming back.

Morpheaform, also called infiltrative, "typically appears as a scar-like, firm plaque" with edges you cannot see clearly. NCI notes those indistinct margins make treatment harder. This is the subtype that argues hardest for margin-controlled surgery.

Actinic keratoses are rough, scaly sun spots. NCI calls them "potential precursors of SCC, but the rate of progression is extremely low."

Bowen disease is squamous cell carcinoma in situ, meaning it sits in the top layer without invading. NCI puts progression to invasive SCC in "the range of 3% to 4%."

Those numbers argue for treating and watching, not for panic.

NCI lists the features that worsen prognosis: tumor diameter, tumor depth, perineural invasion (cancer tracking along a nerve), extranodal extension, anatomic site, immune status, and histologic grade.

The high-risk sites it names for recurrence are the central face, the area behind the ears, the pinna and ear canal, the forehead, and the scalp.

Immune status carries unusual weight here. NCI states that "even with relatively small tumor sizes, SCCs that occur in immunosuppressed patients tend to behave more aggressively." If you have had an organ transplant or take immune-suppressing drugs, say so before anyone chooses a treatment.

Mohs micrographic surgery. NCI describes it as "a form of tumor excision that involves progressive radial sectioning and real-time examination of the resection margins." The surgeon removes a layer, checks it under the microscope while you wait, and goes back only where cancer remains. NCI says it suits recurrent tumors, cosmetically sensitive areas, and tumors with poorly defined borders.

Standard surgical excision. Margins usually run 3 to 10 mm depending on tumor size. NCI cites a trial in which "35 of 199 primary BCCs (18%) were incompletely excised by the initial surgery." Nearly one in five needed more.

Curettage and electrodesiccation. Scraping plus electric cautery. NCI calls it "a widely employed method for removing primary BCCs, especially superficial lesions," and cites a series of 2,314 BCCs in which "the 5-year recurrence rate... after curettage and electrodesiccation was 3.3%" for lesions on the neck, trunk, and limbs.

Cryosurgery. Freezing. NCI says it may be considered for small, well-defined primary tumors, and lists contraindications: the scalp, the nasal ala, the free eyelid margin, and tumors near nerves. In one trial, recurrence by one year was 39% with cryotherapy versus 4% with external-beam radiation.

Radiation therapy. NCI calls it "particularly useful in the management of patients with primary lesions that would otherwise require difficult or extensive surgery." It is avoided in xeroderma pigmentosum and basal cell nevus syndrome.

Topical fluorouracil 5%. FDA-approved for superficial BCCs in patients "for whom conventional methods are impractical." NCI cautions that tumor below the surface can survive treatment of the top.

Imiquimod 5% cream. An immune-stimulating cream. NCI notes that reported complete response rates "vary widely, from about 40% to 100%," and that some specialists "do not recommend it for initial monotherapy for BCC."

Photodynamic therapy. A light-activated drug applied to the skin. NCI reports high initial clearance but "substantial regrowth rates of up to 50%" with long follow-up.

Carbon dioxide laser. NCI says it is "used very infrequently... because of the difficulty in controlling tumor margins."

NCI notes that BCCs "frequently exhibit constitutive activation of the Hedgehog/PTCH1 signaling pathway." Two pills block it: vismodegib and sonidegib, both used for locally advanced or metastatic BCC.

For SCC that has spread or cannot be treated locally, NCI names cemiplimab and pembrolizumab — immunotherapies that block PD-1 — as "the only systemic therapies" for locally advanced and metastatic cutaneous SCC.

Recurrence-free rates across methods land around 85% to 95%. But NCI cites a systematic review with an uncomfortable finding: only about half of recurrences appeared within the first 2 years, and 18% appeared after 5 years. Ten-year recurrence rates were roughly double the 2-year rates.

So a clean two-year check is reassuring, not final. Keep your skin exams going.

The Centers for Disease Control and Prevention (CDC) is specific. When the UV Index is 3 or higher: stay in the shade, "wear clothing that covers your arms and legs," "wear a hat with a wide brim to shade your face, head, ears, and neck," and "wear sunglasses that wrap around and block both UVA and UVB rays." For sunscreen, "use a broad-spectrum sunscreen with a sun protection factor (SPF) of 15 or higher."

CDC notes UV rays are strongest "from 10 a.m. to 4 p.m. daylight saving time (9 a.m. to 3 p.m. standard time)." On tanning beds, CDC states that indoor tanning "exposes users to intense levels of UV rays, a known cause of cancer," and warns that tanning beds can cause serious burns and injuries.

Is this basal cell or squamous cell, and which subtype? Is it nodular, superficial, or morpheaform? Does the report mention perineural invasion or depth? Is this a high-risk site? Am I immunosuppressed, and does that change your recommendation? Is Mohs surgery indicated here, and if not, why not? What is your expected recurrence rate with the method you are proposing? How often should my whole skin be checked from now on?

See also Pathology Reports, Cancer Staging, and Getting a Second Opinion.

• https://www.cancer.gov/types/skin/hp/skin-treatment-pdq
• https://www.cancer.gov/types/skin/patient/skin-treatment-pdq
• https://www.cdc.gov/skin-cancer/prevention/index.html