Kaposi sarcoma is a form of cancer that causes lesions to grow in the skin, mucous membranes, lymph nodes, and other organs. The disease is linked to an infection with human herpesvirus-8 (HHV-8). This virus, also known as Kaposi sarcoma-associated herpesvirus (KSHV), is relatively rare in the general U.S. population. The development of tumors is often associated with a compromised immune system.
General Survival Rates for Kaposi Sarcoma
Statistics for Kaposi sarcoma use a metric called the 5-year relative survival rate. This rate compares people with the same type and stage of KS to the general population. For instance, if the 5-year relative survival rate is 80%, it means that people with that specific cancer are, on average, 80% as likely to live for at least five years after diagnosis as people who do not have the cancer.
The overall 5-year relative survival rate for all stages of Kaposi sarcoma combined is approximately 74%. These statistics are based on data from large numbers of patients and do not predict an individual’s outcome.
Survival Rates by Type of Kaposi Sarcoma
The prognosis for Kaposi sarcoma is closely tied to its clinical type. Epidemic, or AIDS-related, KS is the most common form in HIV-positive individuals. The outlook for this type has improved with the use of highly active antiretroviral therapy (HAART). Effective management of the underlying HIV infection is a main component of treatment.
Classic Kaposi sarcoma primarily affects older men of Mediterranean, Middle Eastern, or Eastern European descent. This form is typically slow-growing, often presenting as lesions on the lower legs, and is associated with a much longer survival time. A study that included a majority of patients with classic KS reported a 5-year overall survival rate of 82.7%.
Endemic, or African, KS occurs in sub-Saharan Africa and presents in two main forms. One form seen in adults tends to progress slowly, similar to classic KS. However, a more aggressive variant exists, particularly in children, which can spread quickly and has a poorer prognosis. This form remains a significant health issue in regions where HHV-8 is more common.
Iatrogenic, or transplant-related, KS develops in individuals whose immune systems are suppressed by medication, such as after an organ transplant. The prognosis often improves if the dosage of immunosuppressive drugs can be safely reduced or the specific medication can be changed. Switching from certain types of immunosuppressants has been associated with the regression of KS tumors.
Influence of Disease Stage and Spread
The extent to which Kaposi sarcoma has spread throughout the body is a significant factor in determining prognosis. Staging systems are used to classify the disease based on its physical extent. The American Cancer Society’s SEER database uses categories such as localized, regional, and distant to track outcomes. Localized disease, where the cancer is confined to one area like the skin, has the best prognosis, with a 5-year relative survival rate of about 82%.
When the cancer has spread to nearby areas or lymph nodes, it is considered regional disease, and the 5-year relative survival rate for regional KS is around 68%. The prognosis becomes more serious when the cancer has metastasized to distant parts of the body, such as internal organs like the lungs, liver, or digestive tract. This is known as distant or visceral disease, and it has a 5-year relative survival rate of approximately 41%. Involvement of internal organs often leads to more severe symptoms and complications, requiring more aggressive systemic treatments.
Impact of Immune System Health
A patient’s underlying immune status is directly linked to their Kaposi sarcoma prognosis. This is most evident in AIDS-related KS, where the health of the immune system is measured by factors like the CD4 cell count. A lower CD4 count, particularly below 200 cells per cubic millimeter, is associated with a more aggressive disease course.
In studies of HIV-positive patients, those receiving HAART have better immune function and higher survival rates; one study reported a 5-year survival rate of 79.3% for this group, compared to 41.7% for those without HAART. This improvement is linked to immune health, as another study showed HAART recipients had an average CD4 count of 335 versus 73 for non-recipients. A stronger immune system is better able to control both the HIV infection and the KS.
For individuals with iatrogenic KS, the ability to modify immunosuppressive therapy is a determinant of their outcome. The prognosis depends on balancing the need to prevent organ rejection with the need to allow the immune system to fight the HHV-8 infection. The overall health of the patient, regardless of the KS type, also plays a part in survival, as patients in better health are more able to tolerate treatments.