New cases of the AIDS-defining cancers non-Hodgkin’s lymphoma (NHL) and Kaposi’s sarcoma (KS) fell significantly in a cohort of HIV-positive women after the introduction of effective anti-HIV treatment, according to a study published in the August 1stJournal of Acquired Immune Deficiency Syndromes. However, the investigators found that even with the use of potent antiretroviral therapy, the incidence of NHL remained elevated in HIV-positive women compared to rates observed in a national US cancer registry.
Investigators also found that HIV-positive women and women at high risk of HIV were more likely to develop lung cancer in the period before anti-HIV treatment became available, but they attribute this increased incidence to smoking rather than immune deficiency.
The Women’s Interagency HIV Study (WIHS) enrolled a total of 2059 HIV-positive and 569 HIV-negative women at high risk of HIV between 1994-95 in six large US cities. Every six months women attend clinic appointments when they have a physical and gynaecological examination and blood tests performed to monitor CD4 cell count and HIV viral load.
Investigators wished to establish trends in AIDS-defining cancers amongst women in the WIHS cohort in the period before and after effective anti-HIV therapy became available. Accordingly, data on the incidence of the AIDS cancers in the WIHS population were gathered. In addition, the investigators compared rates of cancers seen in the WIHS cohort to those seen in the general US population as recorded in the Surveillance, Epidemiology and End Results (SEER) recording scheme.
Data were available on 1554 HIV-positive and 396 HIV-negative women enrolled in WIHS. The majority of these women were African American (54%), and had risk factors for cervical cancer (55% were infected with HPV), and lung cancer (59%) were smokers). On entry to the study 42% of women were coinfected with hepatitis C virus, and a large proportion of the HIV-positive women had a significant degree of immunosuppression with 46% having a CD4 cell count below 200 cells/mm3. Although only 1% of HIV-positive women were taking HAART at baseline this increased to almost two-thirds during the follow-up period (to March 2001).
A total of 48 cases of cancer were recorded in 47 women. The most common cancers were NHL (twelve cases), lung or larynx cancer (ten cases), breast cancer (six cases) and KS (six cases).
"Overall, HIV-infected WIHS women had about twice as many incident cancers as would have been expected among women of similar age and ethnicity in the general female population of the United States", observe the investigators. Significantly increased rates of KS (standardised incidence ratio [SIR] = 213.5), NHL (SIR = 19.0) and lung cancer (SIR = 98.7) were observed in HIV-positive women. HIV-negative women enrolled in WIHS also had a significantly increased incidence of lung cancer (SIR = 6.9).
However, the incidence of cervical cancer was not increased in HIV-positive women, despite the fact that cervical cancer is recognised as an AIDS defining cancer.
The incidence of both NHL and KS dropped significantly in the WIHS population after the introduction of HAART (relative risk 0.15, p = 0.005), however, the incidence of NHL in HIV-positive women remained significantly higher, even during the HAART era, than in the general US age and race matched population (SIR = 6.4).
"The WIHS is strategically positioned to look at cancer risk preceding and during the HAART era. We found evidence of a significant decrease in cancer incidence for NHL since the introduction of HAART", write the investigators, However, they add, "we also found that the incidence of NHL remains significantly elevated among our HIV-infected cohort."
The investigators also comment on the increased incidence of lung cancer seen in their cohort, writing, "our finding of no difference in the incidence of lung/laryngeal cancer, either by HIV serostatus or over time, suggests that factors such as smoking have a greater influence on cancer incidence than HIV infection or HAART use."
The investigators speculate that the reason why there was no evidence of an increased incidence of cervical cancer in the WIHS population, despite the high prevalence of HPV infection, was the regular gynaecological examinations provided to the cohort members.
"In the HAART era, more intensive cancer screening and prevention efforts are warranted…given the higher rates of certain malignancies among HIV-infected women coupled with their increased life expectancy" conclude the investigators.
Further information on this website
HIV and women - booklet in the information for HIV-positive people series (pdf)
Cancers - overview
Hessol NA et al. Cancer risk among participants in the Women’s Interagency HIV Study. Journal of Acquired Immune Deficiency Syndromes 36: 978-985, 2004.