Despite typically having an excellent general health outlook when taking successful antiretroviral therapy, HIV-positive people are apparently less likely to receive treatment for cancer when compared with those who do not have the virus. This possibly helps shed light on why HIV-positive people are less likely to survive cancer.

In the largest study of its kind, researchers compared treatment rates between 3,045 HIV-positive people with over 1 million HIV-negative people who had a variety of common cancers between 1996 and 2010.

Among people who had early stage cancers that have the highest chance of a cure following treatment, those living with HIV were two to four times more likely to go without cancer treatment than HIV--negative people. And as for cases of lung, prostate or colorectal cancer or lymphoma, having HIV meant double the likelihood of going untreated.

“We need to be able to understand what factors are driving those differences and address them so we can improve cancer care for this population,” says the study’s lead author, Gita Suneja, MD, an adjunct assistant professor at the University of Pennsylvania. One likely cause, she says, is that people with HIV are often left out of the randomized clinical trials of cancer treatments that ultimately shape treatment guidelines.