Aspirin Use After Diagnosis Improves Survival in Older Adults With Colon Cancer

A Retrospective Cohort Study

Marlies S. Reimers, MD; Esther Bastiaannet, MSc; Myrthe P. P. van Herk-Sukel, PhD; Valery E. P. Lemmens, PhD; Colette B. M. van den Broek, MD; Cornelis J. H. van de Velde, MD, PhD; Anton J. M. de Craen, PhD; Gerrit Jan Liefers, MD, PhD

Disclosures

J Am Geriatr Soc. 2012;60(12):2232-2236. 

In This Article

Results

Five hundred thirty-six participants aged 70 and older (median age 77.6 ± 5.3) diagnosed with colon cancer between 1998 and 2007 were included in the analyses. One hundred seven participants (20%) started low-dose aspirin (80 mg) after diagnosis, and 429 (80%) did not use prescribed aspirin before or after diagnosis. Table 1 shows participant baseline characteristics. Participants who used aspirin were significantly younger than nonusers. Nonusers were more likely to be diagnosed with Stage IV colon cancer than users, and users were more often diagnosed with Stage I cancer. Most participants did not receive chemotherapy (87%) or radiotherapy (98%). This was similar in both groups. Aspirin users underwent surgery more frequently than nonusers. There were no differences in comorbidities between the two groups.

Survival With Time-varying Covariate

Between 1998 and 2007, 339 participants (63.2%) died; 197 were still alive in 2007. For all participants with colon cancer, aspirin use after diagnosis was associated with significantly lower overall mortality (rate ratio (RR) = 0.51, 95% confidence interval (CI) = 0.38–0.70, P < .001). Multivariate analysis revealed that aspirin use was also associated with longer survival when adjusted for sex, stage, age, adjuvant chemotherapy, comorbidity, incidence year, surgery, and grade (adjusted RR = 0.59, 95% CI 0.44–0.81, P = .00). Figure 1 shows the overall survival curve for aspirin users and nonusers. After stratification for various factors (Figure 2), aspirin users still had better overall survival. The greatest association between aspirin use and survival was in participants with higher disease stage and grade and those who did not receive chemotherapy (adjusted RR for no chemotherapy = 0.71, 95% CI = 0.64–0.79, P < .001). Because older adults are frequently known to have comorbidities, this possible confounder was also stratified for. The association between aspirin use and survival persisted in individuals with diabetes mellitus (adjusted RR = 0.53, 95% CI = 0.32–0.86, P = .01), cardiovascular disease (adjusted RR = 0.69, 95% CI = 0.59–0.79, P < 0.001), no cardiovascular disease (adjusted RR = 0.77, 95% CI = 0.66–0.89, P = .001), and no pulmonary disease (adjusted RR = 0.72, 95% CI = 0.64–0.80, P < .001).

Figure 1.

Survival curve for overall survival in older adults with colon cancer according to use of aspirin.

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