Skin Metastasis (Cutaneous Disease)

Breast cancer skin metastasis, also called cutaneous breast cancer or cutaneous disease, means that breast cancer has spread to the skin. This uncommon condition happens in about 1-10% of people with metastatic breast cancer.

While the cancer is in the skin, it’s still breast cancer, not skin cancer.

People diagnosed with inflammatory breast cancer have a higher risk of developing skin metastasis than people with other subtypes of breast cancer.

Breast cancer skin metastases can have a number of forms. They can appear as red, inflamed skin; a raised, thickened area of skin (called a plaque); a sore that doesn’t heal; or as a solid, raised lump in or under the skin. The skin also may be discolored or have dimples, pits, or ridges, so it looks and feels like an orange peel.

Skin metastases most commonly occur on the same breast as the original cancer, the chest, the arms, and the arm pits; but they can appear anywhere on the body.

It can be difficult to tell the difference between skin metastases and benign skin conditions, like a rash, an allergic reaction, a pimple, or a cyst. But the symptoms of skin metastases get worse over time instead of improving with antibiotics or over-the-counter topical treatments.

A biopsy is almost always required to diagnose skin metastases. If the biopsy shows breast cancer in the skin, your doctor may order other imaging tests, like an MRI or a CT scan to see if the cancer has spread to other places in the body.

Skin metastasis happens when breast cancer cells spread to the skin by growing directly from the breast into it, or by spreading through the bloodstream or the lymphatic system. 

Some research suggests that there may be a link between breast cancer and certain types of skin cancer.

A 2018 study found that people diagnosed with a higher-than-average number of basal cell carcinomas (six or more over 10 years) have a higher risk of other cancers, including breast, colon, and prostate cancer.

A 2020 study found that people with breast cancer have a higher risk of developing melanoma as a second primary cancer. Similarly, people with melanoma have a higher risk of developing breast cancer as a second primary cancer.

There are several reasons for this link. 

Mutations in the BRCA genes increase the risk of both breast and skin cancer. Additionally, mutations in other genes responsible for DNA repair, such as CHEK2 and PALB2, raise the risk of both types of cancer.

Radiation therapy, which is commonly used after lumpectomy to reduce the risk of recurrence, can up the long-term risk of skin cancer in the treated area.

Treating breast cancer skin metastases depends on the symptoms you have; where the metastases are located; the characteristics of the cancer, including its hormone receptor-status and HER2 status; as well as any previous treatments you’ve received.

Systemic treatments

Metastatic breast cancer in any part of the body is usually treated with systemic medicines, which treat cancer throughout the entire body. Chemotherapy, hormonal therapy, targeted therapies, and immunotherapy are all systemic medicines.

Your doctor may recommend a special type of chemotherapy, called electrochemotherapy (ECT) to reduce the size of skin metastases, ease pain, and help heal bleeding, broken skin. It combines a low dose of chemotherapy with electrical pulses.

During ECT, you receive chemotherapy and then your doctor puts a special probe onto the skin metastases. The probe gives off small electrical pulses, which help the chemotherapy medicine get inside the cancer cells.

This is a highly specialized treatment and isn’t available at all cancer centers.

Local treatments

Local treatments, such as surgery, radiation, and drugs applied directly to the skin, like imiquimod, also can be part of the treatment plan. 

In some cases, your doctor may recommend photodynamic therapy, a two-step treatment that uses a photosensitizer medicine and light from a laser or other source that activates it. First the photosensitizer is applied to the skin, taken as a pill, or given through an IV. While all cells absorb the photosensitizer, the medicine stays longer in fast-growing cancer cells. After the cells have absorbed enough medicine — which can take anywhere from a few minutes to a few days, the treatment area is exposed to light. This activates the medicine, creating a chemical reaction that kills the cancer cells. The treatment may cause some immediate side effects including redness, stinging, and burning, much like a nasty sunburn. Over the following days or weeks, the skin in the area may peel and crust or scab over. If the skin lesions are open or infected, you may need specialized dressings and wound cleaning.