Several decades ago, I would venture to say that most people, except some in the medical community, had never heard of Kaposi’s Sarcoma. It existed in the literature, and had been occasionally referenced since the late 19th Century, but it was very rare, and was only found in small segments of the population. Unfortunately, the spread of AIDS has put this type of cancer in the spotlight, as it is very closely linked to AIDS. This article will discuss what is known about this cancer that is much more common than it used to be.
What is Kaposi’s Sarcoma?
Kaposi’s Sarcoma is a type of cancer that manifests itself mainly in the connective tissues of the body such as cartilage, muscle, bone, fat, and blood vessels, or in fibrous tissues of the tendons and ligaments. KS is technically a cancer of the blood vessel walls. A sarcoma (from a Greek word meaning “fleshy growth”) is a cancer that specifically attacks these parts of the body, and the name Kaposi comes from the Austrian dermatologist Moricz Kaposi who was the first to identify and describe the disease in 1872. Kaposi’s Sarcoma (KS) is known for producing characteristic lesions that are typically purple, brown, or red.
Originally, KS was a very rare condition that affected mainly men of Eastern European descent, as well as a small number of men of Mediterranean descent. But the rate of incidence began to increase in numbers and spread into other geographical and racial groups with the onset of the AIDS epidemic. Most cases of KS, about 85%, in the last quarter century are found in HIV- positive men with AIDS. In fact, KS has been designated one of a handful of AIDS-defining conditions, which means that once KS develops in an HIV-positive person, it is a clear sign that they have developed full-blown AIDS. In fact, KS was partially responsible for identifying AIDS because researchers began to see such an unusual number of cases of this rare disease, and this helped them to determine that a new condition was emerging.
Even before the onset of AIDS, there were several types of KS identified, all with different patterns regarding how and where they affect the body. Let’s break it down by type, and see what we can learn about the various characteristics of each.
Classic Kaposi’s Sarcoma
This is the form of KS that was first recognized in the 1870’s. It was found primarily in Eastern European Jewish men and Mediterranean men (mostly Italians) between the ages of 50-70. As a whole, even within these ethnic groups, Classic KS is very rare. When originally documented, its occurrence was much more common in men than women (by a ratio of about 13 men for every woman). However, over the years, even before the advent of the AIDS epidemic, the incidence of Classic KS in women began to increase, until at present it is about 4 cases in men for every case in women. The reasons for this increase in female cases are not known for certain.
Classic KS typically afflicts patients with lesions on the lower legs, ankles, soles of the feet, hands, and/or arms. The lesions often start out small and grow slowly over the years, while adding new ones as well. The disease can progress over a period of 10-15 years in some individuals. Lesions can be painful and disfiguring, but in otherwise healthy people, they are usually not life threatening. Sometimes they will swell to the point of blocking lymph vessels, or spread into the lymph nodes or gastrointestinal tract, causing further complications. However, these developments are rarely found in the Classic form of KS.
African Kaposi’s Sarcoma
Also known as Endemic KS, this is a fairly common form of the condition that is found almost exclusively in individuals that live in equatorial Africa. It is much more common in males than in females, and in fact is responsible for about 9% of all cancers found in Ugandan men. Its characteristics are very similar to Classic KS, with the exception of average age of onset. African KS usually afflicts people at a much younger age than the Classic form. Most of the time, African KS results in skin lesions that are not very problematic, and generally don’t spread to other parts of the body. However, in rare instances, a more aggressive form of African KS may penetrate deeper into the skin, and even into underlying bone tissue.
There is one variant of African KS that attacks mostly younger children, and can spread quickly into the lymph nodes and other organs. This type is found three times as often in boys than in girls, and can be very vicious, often leading to death within three years or less.
Transplant-Related (Acquired) Kaposi Sarcoma
Also known as Iatrogenic KS, is a form of the sarcoma that occurs in organ transplant recipients, typically those who have received a liver or kidney. When organs such as these are replaced, patients are given drugs that help deter the body from rejecting the new organ. Unfortunately, one of the side effects of such medications is that the immune system is weakened, and folks become much more susceptible to infections and diseases of all kinds, including KS. Organ transplant patients are about 150-200 times more likely to develop KS than is the general population. Most cases of Acquired KS affect only the skin, but occasionally it can spread to mucous membranes of other organs of the body. One bit of good news about Iatrogenic KS is that is usually goes into remission without any intervention once the immunosuppressive drugs are discontinued.
AIDS-Related (Epidemic) Kaposi Sarcoma
This form of KS accounts for the majority of KS cases that occur worldwide. People who are infected with the human immunodeficiency virus (HIV) will all too commonly exhibit KS in conjunction with the development of AIDS. HIV attacks certain cells in the immune system, and opens up patients to opportunistic infections and diseases, one of which is KS. Certain cancers seem to afflict folks with compromised immune systems, such as HIV/AIDS victims, more than others. Besides KS, some others include Non-Hodgkin’s lymphoma, central nervous system lymphoma, anal cancer, and invasive cervical cancer.
AIDS-related KS typically manifests itself in lesions that may be widespread throughout the body, usually very soon after AIDS has been diagnosed. Lesions often begin on the upper body, in contrast to Classic KS, including the back, neck, and head. It is also common for lesions to appear in the mucous membranes and soft palate tissues of the mouth and gums, and more advanced cases will expand into the lymph nodes, lungs, liver, spleen, and the gastrointestinal tract. Some patients will have no symptoms when first diagnosed AIDS-related KS, other than simple skin lesions. However, as the illness progresses, swollen lymph nodes, fever, and weight loss may occur. If the disease moves into the lungs, it can be particularly dangerous and potentially fatal. The vast majority of patients will eventually develop KS throughout their body, but the life threatening effects of advanced AIDS-related KS has been greatly reduced due to more affective treatments for the HIV infection and AIDS.
AIDS-related KS is most often found in homosexual or bisexual men. Other behaviors that typically are associated with the spread of AIDS and other sexually transmitted diseases such as intravenous drug use can also increase the risk for an individual developing KS, but dangerous sexual behaviors are ten times more likely to produce KS than the risk of blood transfusions or contaminated needles. This was particularly true in the early days of the AIDS epidemic, before people became educated to the dangers of such risky sexual behaviors. Thankfully, the number of AIDS-related cases of KS is dropping. For example, one study has shown that the number of cases in the Seattle, Washington area has decreased from 366 in the early 1990’s to only 40 several years ago.
What Are the Causes of Kaposi’s Sarcoma?
There seems to be a wide variety of factors that can increase the risk of developing KS. Obviously some of these are behavioral, such as unsafe practices that can expose a person to HIV/AIDS. There are also situational factors, such as the ill effects on the immune system due to drugs administered in association with an organ transplant. But researchers have discovered other patterns that can also affect risk for KS. Some of these include:
- Sex hormones: There is evidence that certain hormones can affect the development of KS tumors. It seems that one of the reasons KS is so much more common in men is that testosterone may actually encourage the growth of this sarcoma. Conversely, women may experience a certain level of protection against KS from the hormone estrogen. Research is ongoing, and the specifics of how these hormonal factors work is not fully understood at this point.
- Genetics: Studies have shown that some folks who develop certain types of KS, mainly Classic and Acquired (Transplant-Related), have a unique genetic factor known as HLA-DR that predisposes them to KS. HLA-DR does not usually run in families, but this doesoccur on rare occasions.
- Compromised immune system: We have already discussed how this plays a role in folks who are HIV or have AIDS, and in organ transplant patients. However, one other common source of increased risk for KS due to immune system repression is found in patients who receive high doses ofcorticosteroid drugs to treat systemic conditions. It seems that KS is one of those cancers that is the most opportunistic when it comes to a weakened immune system.
- Viral causes: There are a number of viruses that may contribute to the development of KS. The presence of several viruses has been confirmed in KS tumors. These include cytomegalovirus and the human papilloma virus (HPV). There is fairly new research that implicates a pathogen known asherpes virus 8 (HHV-8), also known as KS-associated herpes virus (KSHV). First discovered in 1994, KSHV has been found in tumors from several different types of KS, including Classic, African, and Transplant-Related KS.
Kaposi’s Sarcoma is a complex disease, with some forms of it seemingly no more than a painful nuisance, and others a fast-moving killer that can snuff out the life of an otherwise healthy child very swiftly. In minor cases, local therapies such as cryotherapy (freezing the tumors with liquid nitrogen) have been quite successful. More widespread or aggressive forms are often prescribed traditional radiation and chemotherapies. Better treatment of AIDS and HIV infections through effective antiretroviral drugs has accounted for a large part of the reduction in quantity and intensity of KS cases. In most KS patients, treatment of the underlying cause has had the greatest results at combating the disease.