Basal cell carcinoma is the most common type of skin cancer, and it’s not close. About 8 out of 10 non-melanoma skin cancers are basal cell carcinomas, making it the single most frequently diagnosed cancer of any kind in the United States. An estimated 5.4 million basal and squamous cell skin cancers are diagnosed each year in roughly 3.3 million Americans (some people develop more than one), and the vast majority of those are basal cell.
What Basal Cell Carcinoma Looks Like
Basal cell carcinoma develops in the basal cells, which sit at the bottom of the outermost layer of your skin and continuously produce new skin cells. Nearly all of these cancers show up on skin that gets regular sun exposure. In one large study of over 870 cases, 96.8% of basal cell carcinomas appeared on the head and neck. The face alone accounted for about 59% of cases, with the scalp making up another 30%.
The growths themselves can look different depending on the subtype. Some appear as a pearly or waxy bump, often with tiny visible blood vessels on the surface. Others look like a flat, flesh-colored or brown patch that resembles a scar. Some develop a crusty or scabbed center that bleeds, heals, and then bleeds again. That cycle of bleeding and healing without ever fully resolving is one of the hallmark signs. Any sore that won’t heal after several weeks, particularly on a sun-exposed area, is worth getting checked.
How UV Damage Causes the Cancer
The core cause is ultraviolet radiation from the sun or tanning beds, and it works through two distinct pathways. Shorter-wavelength UV rays are absorbed directly by DNA, creating structural damage where two adjacent building blocks on the DNA strand fuse together. These fused pairs, called pyrimidine dimers, are the signature fingerprint of sun-induced mutations. Longer-wavelength UV rays work more indirectly, generating reactive molecules inside cells that cause secondary DNA damage over years of cumulative exposure.
Normally, your cells can detect and repair this kind of damage. But when the repair system is overwhelmed or makes errors, the damage becomes a permanent mutation. In basal cell carcinoma, the mutations follow a predictable pattern. Over 85% of these cancers have defects in a specific cell-growth signaling pathway that normally keeps cell division in check. About half of those mutations carry what researchers call the “UV signature,” a characteristic DNA change that directly traces back to ultraviolet damage. Roughly 50% of basal cell carcinomas also carry mutations in the p53 gene, which is one of the body’s most important tumor suppressors. When both systems fail, basal cells begin dividing uncontrollably.
Who Is Most at Risk
Chronic sun exposure is the biggest risk factor. The threat increases if you live at a high altitude or in a sunny climate, use commercial tanning beds, or have a history of severe sunburns. People with light skin, light-colored eyes, or red or blond hair face a higher risk because their skin produces less of the pigment that helps absorb UV radiation before it reaches DNA.
Less common risk factors include previous radiation therapy to the skin (sometimes used decades ago for acne), exposure to arsenic through contaminated well water or occupational contact, and inherited genetic conditions that impair the body’s ability to repair UV-damaged DNA. Having one basal cell carcinoma also significantly increases the odds of developing another one later.
Treatment and Cure Rates
The good news about basal cell carcinoma is that it grows slowly and almost never spreads to distant parts of the body. The metastasis rate is extremely low, estimated between 0.003% and 0.55%. That makes it one of the most treatable cancers, provided it’s caught before it grows deep into surrounding tissue.
Treatment depends on the tumor’s size, location, and depth. For basal cell carcinomas on the face or other cosmetically sensitive areas, a technique called Mohs surgery offers the highest cure rate: about 98%. During this procedure, a surgeon removes thin layers of tissue and examines each one under a microscope in real time, continuing until no cancer cells remain. This approach removes the least amount of healthy tissue possible. Standard surgical excision, where the tumor is cut out with a margin of normal skin around it, has a cure rate of roughly 93% to 95%. Smaller or superficial tumors can sometimes be treated with freezing, topical medications, or scraping techniques.
Because basal cell carcinoma can be locally aggressive, meaning it invades nearby tissue even though it rarely metastasizes, delaying treatment allows the tumor to grow larger and potentially damage surrounding structures like cartilage or bone, especially on the nose or ears. Early removal is almost always straightforward.
Squamous Cell: The Second Most Common
Squamous cell carcinoma is the second most common skin cancer, making up most of the remaining 20% of non-melanoma cases. It develops in the squamous cells, which are flat cells closer to the skin’s surface. Like basal cell carcinoma, it’s driven primarily by cumulative UV exposure and tends to appear on sun-exposed areas like the face, ears, hands, and forearms.
Squamous cell carcinoma is generally more aggressive than basal cell. It carries a higher risk of spreading to lymph nodes or other organs, particularly when it develops on the lips, ears, or in people with suppressed immune systems. Rough, scaly patches on sun-damaged skin, known as actinic keratoses, are considered precancerous lesions that can progress to squamous cell carcinoma over time, though the exact conversion rate remains uncertain. Treating these patches early is one of the most effective prevention strategies.
How Skin Cancer Costs Add Up
Beyond the personal health impact, skin cancer carries a significant financial burden. Each year, roughly 6.1 million adults in the U.S. are treated for basal and squamous cell carcinomas, costing an estimated $8.9 billion annually. Because these cancers are so common, central cancer registries don’t even routinely track them the way they track melanoma and other cancers, which means the true incidence is likely higher than published estimates suggest.
Consistent sunscreen use, protective clothing, and avoiding tanning beds remain the most effective ways to reduce your risk. People with a history of significant sun exposure or prior skin cancers benefit from annual full-body skin exams, which can catch new growths while they’re still small and easy to treat.