Kaposi's sarcoma

Content

Introduction

Kaposi's sarcoma is a rare tumor caused by a virus, called HHV8, belonging to the herpes virus family. Kaposi's sarcoma originates from cells that line the inside of blood or lymphatic vessels and can occur in the skin and internal organs.

People who have a weakened immune system or a genetic predisposition, those who undergo therapy with drugs that lower the immune defenses such as in the case of a transplant (immunosuppressive drugs) or those who have HIV infection are more likely to get sick with Kaposi's sarcoma. virus that causes AIDS). The probability of developing Kaposi's sarcoma and / or lymphoma for AIDS patients not treated with multiple drug combination therapy (HAART) is approximately 30-40%.

In our country, Kaposi's sarcoma has a low prevalence (about 0.2% in men and 0.7% in women per 100,000 people / year). However, the incidence, that is the number of new cases in a year, increases with increasing age and varies considerably between the geographical areas of the peninsula, with the highest incidence in the South and peaks in the Sassari area, where it is particularly Herpes virus HHV8 is present. Recent estimates by the National Cancer Registry (AIRTUM 2019) speak of less than 1,000 new cases of Kaposi's sarcoma diagnosed in one year in Italy.Today the incidence of this cancer is stable after the growth recorded in the male population in the 1990s, also in correspondence with the spread of HIV infection, which is one of the risk factors.

Symptoms and Diagnosis

The most common initial disorder (symptom) is the appearance of small spots or lesions on the skin, or in the mouth, which appear flat, purplish-red in color and are painless.

Over time they tend to grow and form nodules that merge with each other. They are commonly located on the gums or palate and can cause discomfort for both eating and talking.

Internal organs can also be affected by these injuries, including the lymph nodes, lungs and digestive system. In these cases, the following can occur:

  • annoying swelling of the face, genitals, arms and legs (lymphedema)
  • difficulty breathing, cough, blood in phlegm, chest pain
  • nausea, vomiting, stomach pain and diarrhea
  • swollen lymph nodes, especially peripheral ones (lymphadenopathy), even in the absence of lesions on the skin (cutaneous)

In particular, about 50% of patients who have skin lesions also manifest them in the gastrointestinal tract. Usually, in the stomach and duodenum. Gastrointestinal Kaposi's sarcoma rarely causes (symptomatic) disturbances but can lead to food malabsorption or intestinal obstruction and, more rarely, haemorrhage.

Involvement of the lungs is fairly common and can be life-threatening. It appears in about 20% of patients even without skin lesions and, in this case, both the symptoms (symptoms) that occur and the outcome of the lung radiography do not allow to distinguish with certainty Kaposi's sarcoma from most common lung infections.

How quickly symptoms (symptoms) develop depends on the type of sarcoma.Most types, if left untreated, get worse quickly even over weeks or months. Other types progress very slowly over many years.

If any disorders that suggest Kaposi's sarcoma appear, it is advisable to visit the general practitioner. If you also have HIV, you should contact your hospital directly. If, after the visit, the doctor suspects the presence of Kaposi's sarcoma, he may order further tests to ascertain (diagnose) the disease:

  • HIV test, blood test necessary to confirm or not the presence of the HIV virus
  • skin biopsy, taking a small amount (sample) of cells from the area affected by the lesion to check under the microscope whether or not the typical cells of Kaposi's sarcoma are present
  • endoscopy, an examination that involves inserting a thin and flexible tube, called an endoscope, through the throat to check whether the lungs or digestive system are involved in the lesions
  • computed tomography (CT) to check if the lymph nodes and / or other parts of the body are affected by the disease

Classification

Several types of Kaposi's sarcoma are known:

  • epidemic (or linked to AIDS), typically occurs in people already infected with the HIV virus who therefore have a weaker-than-normal immune system
  • classic (or Mediterranean), mainly affects the elderly from the regions of the Mediterranean (for example, Sardinia), Eastern Europe and the Middle East, areas in which infection with the HHV8 virus, responsible for Kaposi's sarcoma, is rather widespread
  • endemic (or African), concerns the populations of equatorial Africa, an area where HHV8 infection is very widespread and often affects people under the age of 40.In parallel with the spread of AIDS on the African continent, the number of epidemic Kaposi's sarcomas has also increased
  • iatrogenic (or associated with transplant), is found in people who have undergone an organ transplant. These particular patients follow therapies to lower the immune defenses and avoid the rejection of the new organ. The reduction in the activity of the immune system can favor the action of many pathogens, including the HHV8 virus, and increase the risk of developing Kaposi's sarcoma

At the moment there is no official system for the characterization of the extension and spread (staging) of the tumor in the different types of sarcoma, mainly due to the fact that sarcoma is often associated with AIDS for which other factors related to the infection, such as state of the immune system and the presence of other diseases.

Causes

Kaposi's sarcoma is caused by a virus called human herpes virus 8 (HHV8), also known as herpes virus associated with Kaposi's sarcoma (KSHV).

It is thought to spread through sexual activity, saliva, or from mother to baby at the time of birth.

L"HHV8 it is a relatively common virus and most people who carry it do not get Kaposi's sarcoma. The virus can cause cancer only in individuals with a weakened body's defense system or with a genetic susceptibility to it. Indeed, a weak immune system allows the virus HHV8 to multiply until it reaches such a high amount in the blood that it increases the likelihood of Kaposi's sarcoma.

The virus HHV8 seems to work by altering the genetic instructions that control cellular reproduction (replication) and the production, or response, of certain growth factors, called cytokines. They would cause uncontrolled cell growth and tumor formation.

Therapy

If Kaposi's sarcoma has a stable course over time, progresses slowly and does not cause cosmetic complications, immediate therapy is not necessary.

If it is localized on the skin, it can be treated with radiotherapy (a procedure in which X-rays are used), with laser therapy (which uses high-energy light rays), with cryotherapy (based on freezing) or with injections, inside. of the lesion, of various substances such as, for example, interferon alpha and vinblastine.

Immunotherapy and antiretroviral drugs are indicated in people with a more advanced disease. Chemotherapy (treatment in which powerful medicines are used) is more effective, and less toxic, if several drugs are used in combination rather than just one. medicine given in high doses.

Treatments with doxorubicin alone, or doxorubicin-bleomycin-vinblastin, or doxorubicin-bleomycin have a high response rate, equal to 60-90%, and are generally indicated as assault chemotherapy in people with an advanced stage of the disease.

In individuals with few white blood cells (leukopenia), bleomycin-vinblastine therapy is more indicated as it is less toxic to the bone marrow. However, responses to all chemotherapy treatments are effective over a period of time and so-called infections opportunistic are the biggest problem.

Experiments are currently underway with new substances such as taxol, retinoic acid, angiostatic substances. Preliminary results indicate that injections of human chorionic gonadotropin inside the lesions reduce their size. Corticosteroids, on the other hand, make pre-existing lesions worse.

In particular, the treatments are different depending on the type of sarcoma ascertained (diagnosed):

  • epidemic sarcoma, this type of sarcoma can progress quickly if left untreated while well controlled, and it can regress with HIV therapy known as combined antiretroviral therapy. In some people, depending on the area where the tumor lesions are located, their extent, the disorders (symptoms) present, radiotherapy or chemotherapy may also be necessary
  • classic sarcoma, the disorders (symptoms) progress very slowly over the years and are limited to the skin. Immediate treatment is not usually required because in many cases the disease does not affect life expectancy; careful control over time (monitoring) is sufficient. Treatment of ailments is only necessary if they worsen noticeably. Radiotherapy is often indicated as a cure even if small lesions or lumps on the skin can be removed with minor surgery or cryotherapy.
  • endemic sarcomaAlthough classified separately from that associated with HIV infection, many cases can result from undiagnosed HIV infections. Suspected cases, therefore, must undergo HIV testing as the most effective treatment is given by antiviral drugs. anti HIV. In non-HIV-dependent cases, the cause may be genetic vulnerability to the virus HHV8. Usually, they are treated with chemotherapy and sometimes with radiation therapy
  • iatrogenic sarcomausually, the first treatment is to reduce immunosuppressive drugs, whenever possible. If this intervention proves ineffective, it will be necessary to intervene with radiotherapy or chemotherapy

The prediction (prognosis) on the evolution of Kaposi's sarcoma depends on the clinical and immune situation of the sick person. Sometimes, the course of the disease is rapid, other times there are no (asymptomatic) disturbances for many years.

Factors that predict patient survival and are associated with shorter life expectancy are:

  • fever
  • involuntary loss of more than 10% of body weight
  • night sweats
  • number of CD4 + lymphocytes less than 300 per microliter
  • infections related to immune deficiency (opportunistic) in progress or had in the past
  • also the presence of altered cytokines inside the body, when associated with an infection, they can stimulate the growth of lesions

With proper care, Kaposi's sarcoma can be kept under control for many years. Typical skin lesions often become smaller and less noticeable, although they may not heal completely.

A definitive cure is not always possible for all types of sarcoma and, in some cases, the disease may recur (relapse) in the future. Furthermore, being a heterogeneous disease, the treatment must be personalized.

Most people with HIV-associated Kaposi's sarcoma can be successfully treated with combination antiretroviral therapy plus chemotherapy; once the immune system has recovered its function it is unlikely that the cancer will come back (come back).

Innovative therapies for Kaposi's sarcoma are being studied and tested using, for example, drugs that block the formation of new blood vessels, drugs already in use for other types of cancer, immunotherapy, new vaccines and combinations of antiretroviral drugs ( able, that is, to block viruses) with molecules that target HHV8.

Prevention

There are currently no effective vaccines against the virus HHV8 responsible for Kaposi's sarcoma.It is important to try to avoid all behaviors (sexual intercourse with many casual partners, unprotected intercourse) that increase the risk of contracting HIV infection since, by weakening the body's defenses, it facilitates the onset of Kaposi's sarcoma. However, it is very difficult to implement effective prevention strategies since the steps that lead to the development of the disease after HHV8 virus infection are not yet fully understood.

Bibliography

NHS Choices. Kaposi "s sarcoma (English)

Tirelli U. Vaccher E. Neoplastic disease. In: Infectious Diseases. Mosby: London, 1999

Italian Association for Cancer Research (AIRC). Kaposi's sarcoma

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