Background: Radiation therapy (RT) is the core part of cancer multidisciplinary management which causes myelosuppression.
The current standard for RT among HIV-positive cancer patients who are immuno-compromised does not differ from that of HIV-negative ones.
Objective: To determine the effects of radiation therapy on immunological and virological status among HIV-infected cancer
patients.
Material and Method: A prospective observational study was conducted of HIV-infected cancer patients who received
definitive RT in seven hospitals in Thailand. Blood samples were taken to determine immune status using CD4%, and virological status was identified using plasma HIV-RNA viral load (HIV-VL) assay: at baseline before RT; at the last week of RT completion; and at the 6-month follow-up visit. Additional CD4% test was performed at the 3-month follow-up visit.
Results: Ninety HIV-infected cancer patients from seven hospitals in Thailand were included in the analysis. The median age was 40 years old (range 19-61). Seventy-six patients (84.4%) were female and 65 (72.2%) were cases of invasive cervical cancers. Eighty-seven percent of patients had been receiving antiretroviral treatment (ART) before RT. The mean CD4% at baseline, RT completion, 3-month and 6-month follow-up visits, were 18.7%, 20.1%, 16.8% and 17.1%, respectively. The proportion of CD4% reduction in the non-ART group was higher than that of the ART group throughout the period, particularly at the 3-month follow-up visit (100% vs. 29.7%, p = 0.0004). Six cases had a HIV-VL increase of more than 10 times (1-log10) at completion of RT: 3 of these were non-ART, and 3 were ART-uncontrolled viral suppression.
Conclusion: RT had a suppressive effect on immunological status in HIV-infected cancer patients, particularly in the
subacute period among those who were not on ART. HIV-disease progression was observed during radiation treatment in
HIV-infected cancer patients without ART and those with ART-uncontrolled viral suppression.

Keywords: Cancer, Radiation therapy, AIDS, HIV, Antiretroviral, Immunosuppression