Aromatase inhibitors not linked to elevated colorectal cancer risk
Aromatase inhibitors (AIs) do not appear to carry any increase in the risk of developing colorectal cancer, a study reports.
Drawing data from the United Kingdom Clinical Practice Research Datalink, researchers examined breast cancer patients aged ≥55 years who received AIs (n=9,701; median follow-up, 2.4 years) or tamoxifen (n=8,893; median follow-up, 2.9 years) as first-line hormonal therapy.
The risk of incident colorectal cancer in relation to AI vs tamoxifen was estimated by cumulative duration of use and time since initiation using high-dimensional propensity score-adjusted Cox proportional hazards models. All exposures were lagged by 1 year for latency considerations.
Results revealed that the risk of incident colorectal cancer was similar between the AI and tamoxifen groups (incidence rate, 150 per 100,000 person-years in both groups; adjusted hazard ratio [HR], 0.90; 95 percent CI, 0.53–1.52). This was true across analyses stratified by cumulative duration of AI use (p=0.54 for heterogeneity) and time since initiation (p=0.66 for heterogeneity).
The present data show no evidence of an elevated risk of colorectal cancer with AIs when compared with tamoxifen, and this should provide reassurance regarding the safety of AIs to women with breast cancer, researchers said.
“While it is not possible to rule out an increased risk of colorectal cancer with tamoxifen, our findings should be interpreted from context of clinical equipoise as tamoxifen remains the clinically meaningful alternative in management of oestrogen-receptor positive breast cancer,” they explained.
Additional studies with longer follow-up are warranted to confirm the present data, researchers said.