No association exists between postmenopausal breast cancer risk and prolonged analgesic use, according to researchers who conducted a prospective study that involved more than 84,000 women.
Some prior studies suggested regular aspirin use may reduce incidence of postmenopausal, hormone receptor-positive breast cancer by up to 25%, while other studies found no association.
The current study was designed to assess the link between aspirin, other NSAIDs and acetaminophen in regard to overall breast cancer incidence in postmenopausal women, as well as by molecular subtype.
The first portion of the study involved the observation of 84,602 postmenopausal women who did not have cancer at the time of study initiation in 1980. They were followed until June 2008.
Xuehong Zhang, MD, ScD, of Brigham and Women’s Hospital and Harvard Medical School, and colleagues used biennial questionnaires to collect data on analgesic use, reproductive history and other lifestyle factors.
The final analysis included 4,734 documented cases of incident invasive breast cancer.
Regular aspirin use was defined as at least two tablets per week for more than 20 years. Compared with nonuse, regular use was linked to a 0.91 RR (95% CI, 0.81-1.01) for overall breast cancer, a 0.9 RR for ER- and PR-positive breast cancer (95% CI, 0.77-1.06), and a 0.91 RR for ER- and PR-negative breast cancer (95% CI, 0.68-1.22).
Researchers observed no variation in results in terms of past or present aspirin use, days per week of use or dosage levels.
The investigators found no significant association between breast cancer risk and use of other NSAIDs or acetaminophen.
Higher doses were defined as at least six tablets per week for more than 10 years. Use of any analgesic at this level was not significantly linked to overall or subtype breast cancer risk.
Similarly, the researchers observed no link for breast cancer subtypes such as luminal A, luminal B, triple negative, basal-like, HER-2–positive, Cox-2–negative and Cox-2–positive.
In an accompanying editorial, Andrew Jess Dannenberg, MD, director of the Weill Cornell Cancer Center at New York Presbyterian Hospital/Weill Cornell Medical College, and co-authors called the report by Zhang and colleagues an important contribution to scientific literature that explores possible associations between anti-inflammatory drugs and breast cancer incidence among postmenopausal women as a whole.
“The next step is to investigate this strategy where it makes the most sense: in the subset of women with identifiable localized inflammation of the breast,” Dannenberg and co-authors wrote. “Many of these women will be obese, some will be aged, but none of them can be currently identified with conventional clinical tests. To truly test the hypotheses, we need to develop reliable biomarkers for the localized inflammatory lesion, and then conduct clinical trials that can demonstrate that the lesion and its consequences can be reversed and that such a reversal truly lowers risk. Given the frequency of the risk factors (aging and obesity) and the disease, this effort has important public health implications.
“At the same time, it should not escape anyone’s attention that postmenopausal hormone receptor–positive breast cancer, while likely linked to inflammation resulting from obesity, is by no means the only consequence of this unfortunate public health problem,” Dannenberg and co-authors wrote. “Reducing inflammation to prevent the consequences of diet and aging could have broad benefits far beyond oncology, but we will need to perform the right studies to find out. This may be financially painful, but we have much to gain.”