The Human Immunodeficiency Virus (HIV) causes Acquired Immunodeficiency Syndrome (AIDS), which dramatically compromises the body’s defenses. The damaged immune system directly raises the risk of developing certain malignancies. This increased cancer risk is a major health concern for individuals living with HIV, even with modern treatment. The underlying mechanism involves the loss of immune surveillance, which is the body’s ability to police and destroy abnormal cells before they develop into tumors.
How Immunodeficiency Increases Cancer Risk
HIV primarily targets and destroys CD4 T-cells, which are central to the immune system’s function. The depletion of these cells impairs the body’s ability to recognize and eliminate cancerous cells or those infected with cancer-causing viruses. This failure of immune surveillance allows malignant cells to grow and spread unchecked, leading to a higher rate of cancer compared to the general population.
The ongoing presence of HIV also creates chronic inflammation throughout the body, even when the virus is suppressed by medication. This persistent inflammation damages DNA, increasing the likelihood of cellular mutation and abnormal proliferation. The combination of chronic cellular stress and a dysfunctional immune system establishes an environment conducive to cancer development.
The majority of cancers associated with HIV are linked to co-infection with specific oncogenic viruses. A healthy immune system usually keeps these viruses in check, preventing them from transforming normal cells into cancer cells. However, in individuals with HIV-related immunodeficiency, viruses like the Epstein-Barr virus (EBV), Human Herpesvirus 8 (HHV-8), and Human Papillomavirus (HPV) replicate and exert their cancer-promoting effects.
Cancers That Define an AIDS Diagnosis
Certain malignancies are strongly linked to profound immune suppression; their presence in an HIV-positive individual signals the progression to AIDS. These are known as AIDS-defining cancers (ADCs), and they include Kaposi Sarcoma, aggressive Non-Hodgkin Lymphoma, and Invasive Cervical Cancer. ADCs depend on severe immunodeficiency for their development.
Kaposi Sarcoma (KS) develops from the cells lining lymph or blood vessels and is directly caused by Human Herpesvirus 8 (HHV-8). KS lesions often appear as purple or brown spots on the skin but can also affect internal organs like the lungs and digestive tract. For individuals with AIDS-related KS, the cancer results from the immune system’s inability to control the HHV-8 infection.
Non-Hodgkin Lymphoma (NHL) associated with AIDS is an aggressive, high-grade B-cell lymphoma, often linked to the Epstein-Barr virus (EBV). The profound T-cell dysfunction in AIDS patients predisposes them to these lymphomas. Some subtypes, like Primary Central Nervous System Lymphoma, are almost exclusively seen in the context of severe immunodeficiency. The risk of NHL is estimated to be 20 to 70 times higher in people with HIV compared to the general population.
Invasive Cervical Cancer (ICC) is the third ADC, occurring in individuals with a cervix and caused by high-risk types of Human Papillomavirus (HPV). HIV-positive individuals are at a higher risk for persistent HPV infection and rapid progression from pre-cancerous lesions to invasive cancer. The sustained lack of immune control over HPV is the driving factor for this heightened risk.
Increased Incidence of Other Malignancies
Beyond the ADCs, people living with HIV have an elevated risk for Non-AIDS Defining Cancers (NADCs). These cancers are not formal criteria for an AIDS diagnosis but still occur at a higher rate than in the general population. The risk of NADCs remains elevated even when HIV is well-controlled by medication.
Anal Cancer is a notable NADC, with a risk about 25 times higher in the HIV-positive population, and is also caused by the Human Papillomavirus. The immune system’s inability to clear the HPV infection allows the virus to continuously promote abnormal cell growth in the anal canal. This high incidence necessitates specialized screening protocols for people with HIV.
Liver Cancer (hepatocellular carcinoma) is another NADC with increased incidence, largely due to high rates of co-infection with Hepatitis B and C viruses (HBV and HCV) among people with HIV. Chronic infection with these hepatitis viruses causes ongoing liver damage and inflammation, accelerating the development of cancer. The combination of viral hepatitis and HIV-related immune dysfunction creates a co-carcinogenic effect.
Lung Cancer is the most common NADC among HIV-positive individuals in developed countries. Its elevated risk is partially explained by a high prevalence of tobacco smoking in this population. However, the chronic inflammation and immune activation caused by HIV itself also contribute to lung cancer development, independent of smoking. Hodgkin Lymphoma is another NADC with an increased rate, often linked to the Epstein-Barr virus (EBV).
Preventing and Treating Cancer in HIV Positive Individuals
The most effective measure for reducing cancer risk in people with HIV is consistent Antiretroviral Therapy (ART). ART suppresses the HIV virus, allowing the CD4 T-cell count to increase and partially restoring immune function. This immune recovery lowers the incidence of ADCs like Kaposi Sarcoma and Non-Hodgkin Lymphoma.
Preventative measures involving vaccination target the oncogenic viruses that cause most HIV-associated cancers. Vaccination against Human Papillomavirus (HPV) is recommended for all eligible individuals with HIV to protect against HPV-related cancers, including cervical and anal cancers. Hepatitis B vaccination is also important to prevent co-infection and subsequent liver cancer.
Routine cancer screening is an important component of care for people with HIV. Regular cervical cancer screening is recommended to detect precancerous changes at an early, treatable stage. Anal cancer screening, typically through an anal Pap test, is also recommended due to the high incidence of HPV-related disease in this population.
When cancer is diagnosed, treatment protocols involving chemotherapy and radiation therapy are often similar to those used for the general population. However, managing cancer treatment requires close coordination between the oncologist and the HIV specialist. Attention must be paid to drug interactions between cancer medications and the ART regimen to ensure both the cancer and the HIV infection are optimally managed.