Basal and squamous cell skin cancer: Full guide

What are basal and squamous cell skin cancers?

Basal cell carcinoma and squamous cell carcinoma are the two most common kinds of skin cancer. Together they are the most common cancers in the United States. Millions of people are treated for them each year. Doctors sometimes call them keratinocyte cancers or nonmelanoma skin cancers.

They start in cells in the top layer of the skin. The main cause is damage from ultraviolet (UV) light from the sun and tanning beds over many years. That is why they show up most often on the face, ears, scalp, neck, arms, and hands. People with fair skin, light eyes, many sunburns, or a lot of time outdoors have a higher risk, but anyone can get them.

A basal cell cancer often looks like a shiny or pearly bump, a pink patch, or a sore that bleeds, heals, and comes back. A squamous cell cancer often looks like a rough, scaly, or crusty red spot, a firm bump, or a sore that does not heal. Any spot that is new, changing, or not healing should be checked.

Most of these cancers grow slowly and stay in the skin. When they are found early, almost all are cured with a simple procedure in the office. A small number grow deep, come back, or spread. These need more treatment, and new medicines now help many people with advanced disease.

Melanoma is a different, less common skin cancer that is more likely to spread. It has its own guide on this site.

Types and related conditions

Basal cell carcinoma (BCC)

The most common skin cancer. It grows slowly and very rarely spreads to other parts of the body. If it is left alone for a long time, it can grow deep and damage nearby skin, cartilage, or bone.

Squamous cell carcinoma (SCC)

The second most common skin cancer. Most are cured with surgery. A small number spread to nearby lymph nodes or, rarely, to other organs. Doctors call it cutaneous squamous cell carcinoma to separate it from squamous cancers in other organs.

Actinic keratosis

A rough, scaly spot caused by sun damage. It is a precancer. Most never become cancer, but some turn into squamous cell carcinoma. They are often treated with freezing or creams.

Squamous cell carcinoma in situ (Bowen disease)

An early squamous cell cancer that is only in the very top layer of skin. It looks like a red, scaly patch. It is very curable.

Keratoacanthoma

A dome-shaped bump that grows fast over a few weeks. It is usually treated like a squamous cell carcinoma.

High-risk skin cancer

A cancer with features that make it more likely to come back or spread. Examples are a large size, deep growth, growth along nerves, a spot on the ear, lip, or temple, or a cancer in someone with a weak immune system.

Basal cell nevus syndrome (Gorlin syndrome)

A rare inherited condition where people get many basal cell cancers, often starting at a young age.

Other skin cancers

Melanoma and Merkel cell carcinoma are less common skin cancers that act differently and are treated differently. Ask your care team to confirm your exact type.

Tests you may have

Skin exam

A doctor, often a dermatologist (skin doctor), looks closely at the spot and at the rest of your skin. They may use a handheld magnifying light called a dermatoscope.

Skin biopsy

After a numbing shot, the doctor shaves or punches out a small piece of the spot to look at under a microscope. This is the only way to know for sure. It takes only a few minutes.

Lymph node exam

For squamous cell cancer, the doctor feels the lymph nodes near the cancer, such as in the neck or under the arm, to check for spread.

Ultrasound or needle biopsy of a lymph node

If a lymph node feels swollen, an ultrasound can look at it, and a thin needle can take a sample.

CT, MRI, or PET-CT scans

Most people do not need scans. They may be used for large or high-risk cancers to check how deep the cancer goes, whether it grows along nerves or into bone, or whether it has spread.

Margin check

After the cancer is removed, the lab checks the edges of the tissue. Clear margins mean no cancer cells were seen at the edges.

Full-body skin checks

Because having one skin cancer raises the chance of more, your doctor will check all of your skin, now and at follow-up visits.

Stage and risk

Most basal and squamous cell skin cancers are small and are not formally staged. Instead, doctors decide whether the cancer is low risk or high risk. This helps them choose the right treatment and follow-up.

For squamous cell cancer, especially on the head and neck, doctors may use the TNM system. T is the size and depth of the tumor. N is whether cancer is in nearby lymph nodes. M is whether it has spread to distant parts of the body. Stages go from 0 to 4. Ask your care team whether your cancer is low risk or high risk.

Low risk

Small, clearly outlined cancers on the body or arms and legs, in people with a healthy immune system. They are almost always cured with one treatment.

High risk

Cancers that are larger, deeper, or poorly outlined, that grow along nerves, that come back after treatment, or that are on the central face, ears, lips, eyelids, or genitals. People with a weak immune system also have more high-risk cancers. These may need Mohs surgery, radiation, or closer follow-up.

Stage 0

Cancer only in the top layer of skin (in situ).

Stages 1 and 2

Cancer only in the skin, grouped by size and high-risk features.

Stage 3

A deeper or larger tumor, or squamous cell cancer that has spread to one nearby lymph node.

Stage 4

Cancer that has spread to several lymph nodes, grown into bone or the skull base, or spread to distant organs. This is called advanced cancer and is treated with medicines, radiation, and sometimes surgery.

Tumor features and other tests

Gene tests are not usually needed for basal or squamous cell skin cancer. Treatment is based mostly on the type, size, location, and risk features seen under the microscope. A few features matter a lot.

Depth and thickness

How deep the cancer goes into the skin. Deeper cancers are more likely to come back or spread.

Perineural invasion

Cancer growing along a nerve. It raises the risk of the cancer coming back and may lead to radiation after surgery. Numbness, tingling, or weakness in the face can be a sign.

Growth pattern of basal cell cancer

Some basal cell cancers grow in a spread-out pattern (such as infiltrative or morpheaform). These are harder to see and are often treated with Mohs surgery.

How well the cells look (differentiation)

In squamous cell cancer, cells that look very abnormal (poorly differentiated) are more likely to come back or spread.

Hedgehog pathway

Almost all basal cell cancers have changes in a growth signal called the hedgehog pathway. This is why hedgehog inhibitor pills work for advanced basal cell cancer. No test is needed to use them.

Immune status

People who have had an organ transplant, have blood cancers like chronic lymphocytic leukemia, have HIV, or take medicines that weaken the immune system get more skin cancers, and they tend to be more aggressive.

Main treatments

Surgical excision

The doctor numbs the skin, cuts out the cancer with a rim of healthy skin, and closes the wound with stitches. The tissue goes to the lab to make sure the edges are clear. This cures most skin cancers.

Mohs surgery

A special surgery done in the office, layer by layer. The surgeon removes a thin layer, checks all of its edges under the microscope while you wait, and removes more only where cancer is still seen. It has the highest cure rate and saves the most healthy skin. It is used for high-risk cancers and for cancers on the face, ears, hands, and other delicate areas.

Curettage and electrodesiccation

The doctor scrapes away the cancer and then uses an electric needle to treat the base. It is used for small, low-risk cancers on the body. It leaves a round white scar.

Freezing (cryotherapy)

Liquid nitrogen freezes and kills abnormal cells. It is used mostly for precancers and some small, thin cancers.

Creams and light treatment

Prescription creams, such as fluorouracil or imiquimod, can treat precancers, some early squamous cell cancers in situ, and thin superficial basal cell cancers. Photodynamic therapy uses a cream plus a special light. These options do not leave a cut, but they may have lower cure rates than surgery.

Radiation therapy

Used when surgery is hard or not safe, for example in older adults or for cancers on the nose or eyelid. It may also be given after surgery for high-risk squamous cell cancer, such as cancer growing along nerves or in lymph nodes.

Hedgehog inhibitors for advanced basal cell cancer

For basal cell cancer that cannot be treated with surgery or radiation, or that has spread, daily pills called vismodegib or sonidegib can shrink the cancer. Side effects like muscle cramps, taste changes, and hair loss are common, so some people take breaks.

Immunotherapy for advanced squamous cell cancer

For squamous cell cancer that cannot be cured with surgery or radiation, or that has spread, immunotherapy is the main treatment. Cemiplimab, pembrolizumab, and cosibelimab are approved. About half of people see their cancer shrink, often for a long time.

Immunotherapy after surgery and radiation

For some people with squamous cell cancer at very high risk of coming back, cemiplimab given after surgery and radiation lowers the chance of the cancer returning. It is FDA approved for this.

Immunotherapy for advanced basal cell cancer

Cemiplimab can also be used for advanced basal cell cancer that grew on, or could not be treated with, a hedgehog inhibitor.

Clinical trials

Research studies test new treatments, such as giving immunotherapy before surgery to shrink large cancers. Ask if a trial is right for you.

Common side effects and what helps

Wound care after surgery

Keep the wound clean and covered as your doctor tells you. Mild redness, swelling, and soreness for a few days is normal. Call if redness spreads, pus drains, or you get a fever.

Bleeding after surgery

A small amount of oozing is common. Press firmly on it with clean gauze for 20 minutes. Tell your doctor before surgery if you take blood thinners, but do not stop them on your own.

Scarring

Most scars fade over months. Your surgeon may close larger wounds with a skin flap or graft. Sun protection helps scars heal with less color change.

Skin reactions from creams

Fluorouracil and imiquimod creams cause redness, crusting, and soreness in the treated area. This means they are working. It heals after treatment ends. Call if it is very painful or spreads far beyond the area.

Radiation skin changes

The treated skin may turn red, dry, or peel. Use gentle soap and the creams your radiation team suggests. Over time the skin may be thinner or lighter.

Muscle cramps from hedgehog inhibitors

Vismodegib and sonidegib often cause muscle cramps. Staying hydrated and some medicines can help. Your doctor may check a muscle blood test, especially with sonidegib.

Taste changes, weight loss, and hair loss

Hedgehog inhibitors can dull your sense of taste and lead to weight loss. Hair thinning is common. These usually improve after the medicine stops. These pills can harm an unborn baby, so effective birth control is needed.

Immune side effects from immunotherapy

Immunotherapy can cause the immune system to attack healthy organs. This can cause tiredness, rash, itching, diarrhea, cough, or thyroid problems. Most are mild, but some can be serious. Call your team about any new symptom.

Transplant rejection risk

In people with an organ transplant, immunotherapy can cause the body to reject the new organ. Your cancer and transplant teams need to plan together.

Living with and after skin cancer

After one skin cancer, the chance of getting another is high. Many people get a new one within 5 years. That is why regular skin checks with your doctor matter, often once or twice a year, and more often if you had a high-risk cancer.

Check your own skin once a month in good light. Use a mirror or ask someone to help with your back and scalp. Look for new spots, sores that do not heal, rough patches, or bumps that grow or bleed. Tell your doctor about any change.

Protect your skin every day. Seek shade, especially between 10 a.m. and 4 p.m. Wear a wide-brimmed hat, sunglasses, and long sleeves. Use a broad-spectrum sunscreen of SPF 30 or higher on uncovered skin, and reapply every 2 hours outdoors. Never use tanning beds.

For people who get many skin cancers, a vitamin called nicotinamide (a form of vitamin B3, not niacin) may lower the number of new ones. Ask your doctor before starting it. Some people also use creams like fluorouracil on large sun-damaged areas to treat precancers before they turn into cancer.

People who have had an organ transplant have a much higher risk, especially of squamous cell cancer. They should have skin checks often, at least once a year and often every few months. Their transplant doctors may change their anti-rejection medicines, for example to sirolimus or everolimus, or add a pill called acitretin to lower the number of new cancers. Never change transplant medicines on your own.

Most people with these cancers are cured. If you have advanced cancer, it is normal to feel worried. Support groups and counselors can help, and your care team is there for you.