HIV-positive women with breast cancer appear to have reduced overall survival compared with HIV-negative women, according to research presented at the Conference on Retroviruses and Opportunistic Infections (CROI 2019) in Seattle.
Although having HIV was associated with a nearly twofold reduction in survival, both HIV-positive and HIV-negative women had high five-year mortality, said Katrin Sadigh, MD, of Brigham and Women’s Hospital in Boston.
As people with HIV live longer thanks to effective antiretroviral therapy, AIDS-related mortality has dropped and noncommunicable diseases, such as cancer and cardiovascular disease, now account for a growing proportion of deaths. Breast cancer is the leading cause of cancer-related death for HIV-positive women with access to effective antiretrovirals, as it is for HIV-negative women, Sadigh noted.
The researchers conducted a prospective study looking at the effect of HIV on overall survival among women with breast cancer in a resource-limited setting. The study drew from the Thabatse Cancer Cohort, which includes nearly 4,000 people with cancer who receive care at four major oncology centers in Botswana.
The breast cancer cohort included 510 women who received cancer care at public or private facilities between October 2010 and September 2018. Of these, 151 were HIV positive and 327 were HIV negative. The HIV-positive women were younger, on average, than the HIV-negative group (median 47 versus 56 years).
Both HIV and cancer care are provided free by the Botswana government, Sadigh said. Most women with HIV (85 percent) were on antiretroviral therapy at the time of their cancer diagnosis, and 70 percent had suppressed viral load. The most common regimens, each used by about a third of participants, were zidovudine (AZT)/lamivudine (3TC)/efavirenz (Sustiva or generics) and tenofovir disoproxil fumarate/emtricitabine/efavirenz (the drugs in Atripla).
In both the HIV-positive and HIV-negative groups, about 5 percent had Stage I early breast cancer at the time of diagnosis; about 25 percent had Stage II cancer that had spread to nearby lymph nodes; 40 percent had Stage III disease that had grown and spread further into nearby tissues; and 15 percent had Stage IV or metastatic cancer that had spread to other parts of the body, such as the bones or brain.
About a third of the women in both groups had estrogen-receptor-positive tumors, meaning they grow when exposed to estrogen and can be treated with hormone-blocking drugs such as tamoxifen. About 15 percent had triple-negative breast cancer that has no receptors for estrogen, progesterone or the HER2 protein, meaning it does not respond to hormone therapy or HER2 inhibitors such as Herceptin (trastuzumab). About 40 percent did not receive this type of testing.
Breast cancer treatment did not differ by HIV status. In both groups, about 70 percent of women underwent mastectomy, or complete breast removal, and about 10 percent received lumpectomies to remove tumors. About 60 percent were treated with some type of chemotherapy and just under half received radiation therapy.
Seventy HIV-positive women (46 percent) and 101 HIV-negative women (31 percent) died during the five years of follow-up. In both groups, cancer was by far the leading cause of mortality, accounting for around 90 percent of all deaths; in addition, about 3 percent of deaths were attributed to adverse effects of cancer treatment. None of the HIV-positive women died of AIDS-related causes.
In an analysis that controlled for other factors, HIV-positive women were found to have an 82 percent reduction in survival compared with HIV-negative women, Sadigh reported.
There was little difference in mortality among women with Stage IV cancer, who had a high death rate regardless of HIV status. However, HIV appeared to have a greater detrimental effect on survival in women with early-stage breast cancer and those with hormone-receptor-negative tumors. Unexpectedly, the impact of HIV was greater among women with higher CD4 counts (above 350), but Sadigh was unable to explain the reason for this finding.
Based on these findings, the researchers concluded, “HIV infection was associated with nearly twofold reduction in breast cancer survival despite good access to antiretroviral therapy. Differences in cancer stage, cancer subtype or access to cancer treatment does not explain the disparity.”
Importantly, overall survival was poor for both HIV-positive and HIV-negative women in this study, and better approaches are needed to speed up diagnosis and improve care, Sadigh said.