Nonaspirin NSAIDs associated with renal cell cancer

Nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) were associated with an elevated risk of renal cell cancer, especially among those who took them for a long time, while aspirin and acetaminophen were not associated with such risk, an analysis found.

Researchers examined the relationship between analgesic use and renal cell cancer using data from the Nurses' Health Study (beginning in 1990) and the Health Professionals Follow-up Study (beginning in 1986). Results appeared in the Sept. 12 Archives of Internal Medicine.

During a follow-up of 16 years among 77,525 women (1,106,683 person-years) and 20 years among 49,403 men (807,017 person-years), there were 333 renal cell cancer cases (153 women and 180 men). Aspirin and acetaminophen use was not associated with renal cell cancer risk. However, regular use of nonaspirin NSAIDs was associated with an increased renal cell cancer risk (pooled multivariate relative risk [RR], 1.51; 95% CI, 1.12 to 2.04) at baseline compared with nonregular use. The absolute risk differences for the users versus nonusers of nonaspirin NSAIDs were 9.15 per 100,000 person-years in women and 10.92 per 100,000 person-years in men.

There was also a dose-response relationship. Compared with nonregular use, the pooled multivariate RRs were 0.81 (95% CI, 0.59 to 1.11) for NSAID use less than 4 years, 1.36 (0.98 to 1.89) for 4 to less than 10 years, and 2.92 (1.71 to 5.01) for 10 or more years (P<0.001 for trend).

Researchers mutually adjusted for the three types of analgesics in a multivariate model. The positive association between nonaspirin NSAIDs and renal cell cancer risk remained essentially unchanged. The pooled multivariate RR was 3.00 (95% CI, 1.74 to 5.18) for those who used nonaspirin NSAIDs 10 or more years compared to nonusers.

Researchers also examined nonconsecutive versus consecutive use. In women, the RRs for nonconsecutive and consecutive use were 4.01 (95% CI, 1.98 to 8.29; 11 cases) and 2.40 (CI 0.72 to 7.95; 3 cases), respectively. All of the men taking NSAIDs for 10 or more years were nonconsecutive users. After prevalent users of nonaspirin NSAIDs at baseline were excluded, few cases remained among those with 4 or more years of use. When men taking NSAIDs for 4 to 10 years and 10 years or more were combined as a group, no significant association was found.

In women, there was a linear increase in renal cell cancer risk with increasing frequency of use. Compared with nonuse, the RRs were 1.08 (95% CI, 0.67 to 1.74), 1.30 (0.71 to 2.39), and 1.86 (1.19 to 2.90) for use of 1 to 4 days per month, 5 to 14 days per month, and more than 15 times per month, respectively.

Because some participants used more than one analgesic, researchers evaluated the associations among individuals who used one medication exclusively by excluding those who also took other analgesics. The results were essentially similar. The pooled multivariate RR was 1.57 (95% CI, 1.07 to 2.33) for those who exclusively used nonaspirin NSAIDs compared with those who did not.