What is Kaposi’s sarcoma?
Kaposi’s sarcoma is a soft tissue malignancy. These cancers develop in the soft tissues that make up the musculoskeletal system. This includes muscle, fat, cartilage, connective tissue, nerves, and blood and lymph vessels.
Kaposi’s sarcoma is a vascular sarcoma. It starts in the cells of the lining of blood or lymph vessels causing purple, red or brown areas or lesions on the skin and mucous membranes. The tumors can also affect other body parts, such as the lymph nodes, liver, lungs, and digestive tract. You may also see it called Kaposi sarcoma. It gets its name from the doctor who first described it, Dr. Moritz Kaposi.
There are four types of Kaposi’s sarcoma based on the population it affects. In all four types, it is related to some factor that weakens the immune system. This allows a herpesvirus—human herpesvirus 8 (HHV8)—to infect cells and cause cancerous changes.
The four types of Kaposi sarcoma are:
- Classic or Mediterranean Kaposi’s sarcoma mainly affects older people of Mediterranean, Middle Eastern, or Eastern European descent. It’s more common in men than women and is usually slow growing.
- Endemic or African Kaposi’s sarcoma mainly affects people in equatorial Africa. It tends to strike younger people, including women.
- Epidemic or AIDS-related Kaposi’s sarcoma affects people with HIV (human immunodeficiency virus) infection. Kaposi’s sarcoma is an AIDS-defining infection. This means its occurrence indicates that an HIV-positive person officially has AIDS (acquired immune deficiency syndrome). This is the most common form of Kaposi’s sarcoma in the United States. However, effective HIV treatments have decreased its prevalence.
- Iatrogenic or transplant-related Kaposi’s sarcoma affects transplant recipients who take immunosuppressive drugs to protect the transplant from rejection.
Kaposi’s sarcoma treatment depends on several factors. This includes the disease type, the number and location of the lesions, the symptoms the condition is causing, and your general health. Treatments for localized lesions include surgery, radiation, and intralesional chemotherapy. When the disease is widespread, options include systemic chemotherapy and immunotherapy.
If you are at risk of developing Kaposi’s sarcoma, see your doctor promptly for any suspicious lesions on the skin or mucous membranes. You should also be evaluated for unusual symptoms, such as swelling of the legs and feet, shortness of breath, or abdominal pain.
What are the symptoms of Kaposi’s sarcoma?
Kaposi’s sarcoma most commonly manifests as skin lesions that are purple, red or brown. Lesions can also affect the mucous membranes, such as the inside of the mouth, throat or eyelids. When the lesions are flat, they are called patches. Slightly raised lesions are plaques and lesions that appear as bumps are called nodules. The face and legs are the most common sites for Kaposi’s sarcoma lesions, but they can appear just about anywhere. Typically, Kaposi lesions do not cause pain or itchiness.
Other symptoms of Kaposi’s sarcoma
Kaposi’s sarcoma can cause other symptoms, depending on whether or not it affects other body parts. Possible Kaposi’s sarcoma symptoms include:
- Abdominal pain and diarrhea
- Swelling in the legs and feet, which can be painful
If you have symptoms that persist or worsen, it’s important to see your doctor promptly. In general, the earlier you find cancer, the better the prognosis.
What causes Kaposi’s sarcoma?
Cancers, in general, occur as a result of DNA mutations in the genes controlling cell growth. These mutations let cells grow out of control. In Kaposi’s sarcoma, a virus—human herpesvirus 8 (HHV8)—infects the cells lining the blood and lymph vessels. The virus introduces genes into the cells’ DNA that allow them to grow too fast and live longer than normal. HHV8 is also called Kaposi’s sarcoma-associated herpesvirus (KSHV).
What are the risk factors for Kaposi’s sarcoma?
KSHV infection is common, especially in certain areas of the world. In the United States, less than 10% of people have the infection. In contrast, about 80% of people in Africa have KSHV. However, most people with the infection do not develop Kaposi’s sarcoma.
The main risk factor for developing Kaposi sarcoma is having KSHV infection with a weakened immune system. In the classic or Mediterranean type, older age likely weakens the immune system enough to allow development of lesions. In the endemic form, herpesvirus infection, malnutrition, and malaria and other infections contribute to immune system weakness. AIDS-related Kaposi’s sarcoma is directly related to immune suppression from HIV infection. Similarly, the transplant-related form happens due to drugs that suppress the immune system.
Other risk factors include:
- Being biologically male: Males are more likely to develop Kaposi’s sarcoma compared to females.
- Ethnicity: Kaposi’s sarcoma is more common in people of Mediterranean, Jewish, Middle Eastern, and Eastern European heritage and people living in equatorial Africa.
- Sexual activity: HHV8 and HIV are both more common in men who have sex with men, leading to a higher risk of Kaposi’s sarcoma.
Reducing your risk of Kaposi’s sarcoma
In the United States, most cases of Kaposi’s sarcoma are related to HIV infection. So, the main way to prevent Kaposi sarcoma is to reduce the risk of becoming infected with HIV. For people who are HIV-positive, there are steps to take to reduce the risk of developing Kaposi’s sarcoma. This includes taking HAART (highly-active antiretroviral therapy) to control HIV and antivirals to treat herpesvirus infection.
How is Kaposi’s sarcoma treated?
Kaposi’s sarcoma treatment options depend on the specific type of the disease, number of lesions, location of the lesions, symptoms, and your general health.
AIDS-related Kaposi’s sarcoma
The most important part of treating AIDS-related Kaposi’s sarcoma is using an effective combination of HIV drugs. HAART can improve immune function and help shrink Kaposi’s sarcoma lesions. Other treatments may be necessary to treat symptoms or if HAART is no longer able to control the cancer. This can involve local therapy with radiation, cryotherapy, intralesional chemotherapy, surgery, or topical retinoids, if there are few lesions.
When lesions are widespread, chemotherapy or immunotherapy may be options. However, some people may not be able to tolerate systemic chemotherapy.
Transplant-related Kaposi’s sarcoma
Oftentimes, switching immunosuppressive drugs will resolve transplant-related Kaposi’s sarcoma. In particular, using sirolimus (Rapamune) or everolimus (Afinitor, Zortress) can be effective at protecting the transplant from rejection while shrinking Kaposi’s lesions. Doctors may also recommend radiation therapy or another local treatment for skin lesions. Chemotherapy is generally not an option for this population.
Classic Kaposi’s sarcoma
This form of the disease is typically slow-growing. Local treatments are often enough to control the disease. Doctors may recommend chemotherapy for widespread lesions or symptoms involving the lungs or other organs.
Endemic Kaposi’s sarcoma
Treatment options are often limited due to poverty in the countries where the endemic form occurs. Treatment options are generally the same as other forms and include both local and systemic options.
What are the potential complications of Kaposi’s sarcoma?
The overall prognosis for Kaposi’s sarcoma is good and has improved dramatically over the last few decades. The 5-year relative survival rate for localized lesions is 82%. This means people who have localized Kaposi’s sarcoma are, on average, 82% as likely to be alive five years after diagnosis as someone without the cancer. (Localized lesions are only in one area, such as the skin or mucous membranes.) The survival rate decreases with regional and distant spread of the cancer.
It’s important to remember that survival rates are only statistics. They can’t tell you what your future will be. Your outlook depends on many factors, including your immune system status and your overall health. Treatments also evolve and improve with time. Your doctor is the best source for understanding your individual prognosis.