Before the advent of anti-retroviral therapy, which aims to keep the virus in check, Scottish patients were at 11 times the risk of all cancers combined and more than a hundred times more likely to develop certain types.
Some cancers – known as AIDS defining malignancies – were already strongly linked to HIV infection, which works by gradually destroying the immune system. The new study also found increases in a number of other cancers, including lung, liver and skin cancer.
Researchers are now planning to monitor the current generation of HIV patients, in order to evaluate the effectiveness of the new anti-HIV drugs at bringing down cancer rates.
Researchers at the Universities of Strathclyde and Glasgow and the Scottish Cancer Registry in Edinburgh examined data from 2,574 people diagnosed with HIV in Scotland. They analysed records between 1981 and 1996, when anti-retroviral drugs were first introduced, in order to measure the increase in cancer risk from infection with HIV.
HIV patients in general were 11 times more likely to develop cancer, although the risk varied between different groups. The risk among haemophiliacs and heterosexuals was five times higher than the population as a whole, but this jumped to 21 times higher than normal for homosexual and bisexual men.
Scientists were particularly intrigued at increases in a number of cancers not regarded as ‘AIDS-defining’. The risk of lung cancer quadrupled among HIV patients, the risk of liver cancer went up by 22 times and the risk of skin cancer2 tripled.
Lead author Dr Gwen Allardice, of the University of Strathclyde, says: “We expected a number of cancers already linked to HIV would be more common in Scottish patients, but the rises in lung, liver and skin cancer were more surprising.
“It could be that HIV patients are smoking more or have greater exposure to other viruses such as Hepatitis B and C, or it might be because a healthy immune system plays a stronger role than we thought in keeping these cancers at bay.”
The study also found the expected increases in AIDS-defining cancers. Kaposi’s sarcoma, a normally rare type of skin cancer, went up by over 2,000 times, while non-Hodgkin’s lymphoma increased by about a hundred times.
It will now be important to track the effectiveness of anti-retroviral drugs, to see if cancer rates among the current generation of HIV patients have returned to nearer that of the rest of the population.
Dr Richard Sullivan, Head of Clinical Programmes for Cancer Research UK, which owns the British Journal of Cancer, says: “HIV takes effect by dismantling the immune system. It not only strips people of their ability to fight infections, some of which can cause cancer, but may also prevent the body from being able to recognise and destroy cancer cells.”
He adds: “With this new study, we now have a valuable insight into the kind of cancers which are linked to HIV. It will help doctors to monitor the health of today’s HIV patients, who are at least fortunate enough to have the benefit of anti-retroviral drugs.”
- British Journal of Cancer89 (3)
- Not including the AIDS-defining malignancy, Kaposi’s sarcoma