Higher Risk of Certain Cancers Being Recorded in HIV-Positive People
Physicians in the U.S. are reporting a higher risk for certain types of cancers -- such as liver, head, neck and lung -- in people living with HIV/AIDS, raising concerns that a cancer epidemic is imminent in the population, the Baltimore Sun reports. According to the Sun, Meredith Shiels, a doctoral candidate at the Johns Hopkins Bloomberg School of Public Health, presented a paper on Tuesday at the seventh annual American Association for Cancer Research International Conference on Frontiers in Cancer Prevention Research that said people living with HIV are twice as likely as the general population to develop cancers not previously linked with the virus. Other studies have found that people living with HIV have as much as a 10 times greater chance of developing certain cancers compared with the general population. William Blattner, an associate director of the University of Maryland Institute of Human Virology, said researchers are "really at the first stages of systematically looking at the epidemic and fully looking at cancer." He added that "[b]efore, you died from AIDS, so you didn't have time to develop cancer. ... The unusual observation is the cancers are occurring at a much younger age."
Although researchers do not know the exact reasons for the increased risk of developing some cancers, there are several theories as to why HIV-positive people are more susceptible, such as the increased life expectancy due to antiretroviral drugs; weakened immune systems related to the virus or the effects of antiretrovirals; and the likelihood of increased high-risk behaviors in people living with HIV. The Sun reports that a well-known researcher "wonders" if antiretrovirals could be a carcinogen. In addition, many cancers found in people living with HIV are known to be caused by viruses, such as anal, head, neck and cervical cancers -- which have been linked to the human papillomavirus -- and liver cancer, which has been linked to hepatitis. Mark Wainberg, director of the McGill University AIDS Center in Montreal, said, "There's a real concern about all these cancers and what they portend. Obviously, we don't want an epidemic of cancers in long-term HIV-infected people."
According to the Sun, physicians have discovered that treatments for cancer do not work as well in patients who have compromised immune systems, and some researchers have suggested that cancer develops regularly in all people but the immune system is able "to keep most of them in check." A person living with HIV may not have an immune system that is able to do this as effectively, the Sun reports. However, people with HIV who develop cancer do not "always have the weakest immune systems, further confounding researchers," according to the Sun. Eric Engels, a researcher at the National Cancer Institute studying HIV/AIDS and lung cancer, said research into how the immune system and cancer interact could provide a wider application than just helping people living with HIV. "This research has implications for people who have a healthy immune system, too," he said.
The Sun also reports that cases of lung cancer among people living with HIV are increasing, and a 2003 study conducted by Johns Hopkins thoracic surgeon Malcolm Brock found 80 cases of HIV-positive lung cancer patients out of a total 12,000 lung cancer patients who received treatment at Johns Hopkins Hospital dating back to 1950. Brock said people living with HIV have a three to five times higher risk of developing lung cancer than the general population, with a high risk even when controlled for smoking. He also said the median age of lung cancer patients who are living with HIV is 46, compared with 64 among the general population. "The deaths here were overwhelmingly cancer-related. They were not due to AIDS," Brock said, adding that "these patients die and they die quickly," with an average period of six years between HIV diagnosis and lung cancer diagnosis. Engels said that although the cancer is not caused by a virus, it could be the result of an unknown infection, scarring of the lungs or some type of inflammation, which could explain why it is increasingly being found in people living with HIV.
Shiels said that the trend in cancer development in HIV-positive people might have been detected earlier if antiretrovirals were developed sooner. "Perhaps if they had lived longer, we would have seen this 10 years ago," she said. Kevin Cullen, director of the University of Maryland Greenebaum Cancer Center, said that 10 or 20 years ago "virtually no one [living with HIV] who developed cancer could survive rigorous cancer treatment," but antiretrovirals have allowed people to successfully undergo cancer treatment.
Wainberg said that recent gains in HIV/AIDS treatment have given some people who are at high risk for contracting the virus a false sense of security. "There is no doubt that there are people among vulnerable groups who now have a bit of an attitude of ... 'If I get HIV, the drugs are going to help me anyway,'" he said, adding that high-risk groups need to know about the risks of cancers associated with HIV. Engels said that recent findings involving an increased risk of cancer among people living with HIV should not reduce the developments in HIV/AIDS treatment in the U.S. He said, "If you had to pick a time and a place to live with HIV infection, America today would be the best time and place we've ever had. But we're finding these problems coming to the surface that we didn't see before" (Desmon, Baltimore Sun, 11/19).