Why HIV increases your risk for cancer

HIV and cancer have always commanded an inordinate amount of trepidation from humans, and, it seems, the two were always birds of a feather. In fact, cancer was a major reason HIV was discovered. In 1981, a number of gay men presented with a rare lung infection and an aggressive form of soft-tissue cancer; the Kaposi Sarcoma. In the course of investigating what was causing the cancer, HIV was discovered.

Today, Kaposi Sarcoma is one of the most common cancers in HIV positive patients, yet is generally a rare cancer in people without HIV. It is one of the three cancers referred to as “Aids-defining” cancers, which means that having HIV together with any one of these cancers may mean that Aids has developed.

“We know that HIV increases the incidences of certain cancers. The Centres for Disease Control and Prevention (CDC) has certain cancers that they classify as “Aids-defining” cancers. That would be Kaposi Sarcoma, Non-Hodgkin lymphoma (NHL) and cervical cancer. The incidences of those cancers are higher in HIV-positive patients,” says Dr Angela Waweru, a radiation oncologist at the Aga Khan University Hospital in Nairobi.

Jacinta Wambui, a 40-year-old woman from Kiambu County only found out she was indeed HIV positive five years after her husband succumbed to tuberculosis. She had been too afraid to get tested earlier, but now had to do it because she was pregnant.

“When I gave birth, I did not stop bleeding for about one and a half years. When I finally went to hospital, they found that I had stage II cervical cancer,” she says.

And going by a report by Joint United Nations Programme on HIV/Aids (UNAids), it isn’t so unusual that Wambui would be diagnosed. Cervical cancer, they say, is the most common cancer among HIV positive women. Infact, the likelihood that a woman living with HIV will develop invasive cervical cancer is up to five times higher than for a woman who is not living with HIV.

On the flip side, HPV infection, many strains of which cause cervical cancer, has also been found to significantly increase the risk of HIV transmission for both men and women.

While the reason women living with HIV are much more likely to get cervical cancer isn’t completely clear, according to UNAids, women living with HIV who become infected with HPV are more likely to develop pre-invasive lesions that can, if left untreated, quickly progress to invasive cancer.

Testing for HPV would, however, prevent most incidences of invasive cervical cancer even among HIV positive women.

“Improved access to high-functioning HPV testing and other cervical cancer screening modalities would substantially decrease the burden of cervical cancer for women living with and without HIV,” says Dr Scott Dryden-Peterson, a research associate with the Botswana-Harvard Aids Institute.

 Adhering to treatment can reduce risk for all but cervical cancer

Although studies have associated proper adherence of antiretroviral treatment (ART) with reduced incidence of the other Aids-emergent cancers such as Kaposi Sarcoma and non-Hodgkin lymphoma, they have not found a similar reduction in the incidence of cervical cancer.

It is suggested that it may be because most women do not start ART until their CD4 count is low and their viral load is high. Dryden-Peterson says that early detection of HIV infection could also reduce the risk of cervical cancer. Another study by Kelly and associates shows that earlier initiation of ART and better adherence may decrease the risk of HPV infection and progression to cervical cancer.

This may have been the issue for Wambui, who was not tested until five years after her husband died of HIV, and therefore also started out with a low CD4 count.

What causes it...

As to how HIV can be a direct cause of cancer, studies by UK’s cancer research organisation explain that HIV infects and kills T-cells which are part of our immune system that usually help to get rid of infections. Some of these cancers are brought about by viral infections. In people without HIV, the immune response can help clear the virus before cancer can develop. But people with HIV have fewer T-cells, so they can’t fight infections as easily.

Also, it is less common, but people with HIV or Aids may develop other cancers which are “non-Aids defining” such as Hodgkin lymphoma, Angiosarcoma (found in blood and lymph vessels, anal cancer, liver cancer, mouth cancer and throat cancer, lung cancer, testicular cancer, penile cancer, colorectal cancer and some types of skin cancer, including basal cell carcinoma, squamous cell carcinoma, and melanoma.

Dr Waweru also says for other more common cancers like breast cancer and prostate cancer, while there is no evidence, they tend to be more common in HIV positive patients.

 Is cancer treatment same as that of HIV-negative persons?

Waweru says that HIV patients with cancer should be and are treated exactly the same as the HIV free.

“Most of us in Kenya use the National Comprehensive Cancer Network (NCCN) guidelines, which are American. In them, it has been clearly documented that for the treatment of cancer in HIV patients, the treatment algorithm should be exactly the same as a non-HIV patient,” she says.

She explains that the only difference is that for HIV patients, they have to take more caution.

“If, for instance, a patient comes to me and is known to be HIV positive, we interrogate their CD4 and viral load. Thankfully, HIV control in Kenya is very good. So most patients come with an undetectable viral load and a good CD4 count. In that case, they will receive the exact same treatment. That means even patients who need intensive, high-dose chemotherapy also get it, provided that their CD4 count and viral load are considered adequate,” she says.

However, even when it is determined the patient has good CD4 count and viral load, the oncologists still engage their infectious disease experts or HIV specialists because sometimes the ARVs can interact with the chemotherapy drugs they choose.

“It is best practice to always engage an infectious diseases specialist to confirm that the treatment we are giving them doesn’t interact with their ARVs. Most times there is no interaction, so it isn’t often that we have to change treatment,” she says.

“In the case where a patient comes and their HIV control is not very good, we give them the treatment but we monitor them closely because we know that there is a risk that some of our treatments can cause them to be immunosuppressed and they would be at a particular risk of getting opportunistic infections,” she says.

Despite the odds being severely stacked against her, Wambui caught a lucky break because if diagnosed early, cervical cancer is curable. Surgery is the most common treatment for cervical cancer. It is sometimes combined with chemotherapy or radiation but she did not undergo any of the two.

Thanks to a donor who footed the bill, she underwent surgery at Nazareth Hospital to remove the cancerous tissue. Six months later, the cancer was in remission and she has been cancer-free since. She also has an undetectable viral load and is assisted in living with the condition by Kiambu People Living with HIV (Kipewa), an NGO that caters to people living with HIV and Aids.