Evaluation of the clinical impact of concomitant acid suppression therapy in colorectal cancer patients treated with capecitabine monotherapy.

Background Capecitabine is an oral chemotherapeutic agent used in colorectal cancer. Two prior studies found a negative impact with the concomitant use of proton pump inhibitor agents during treatment with capecitabine in patients with early colorectal and gastroesophageal cancers. Objective To determine if there is a clinical impact of the concomitant use of capecitabine and acid suppression therapy in patients with local and metastatic colorectal cancer. Methods This was a single-center retrospective cohort study of adult patients with colorectal cancer on capecitabine monotherapy between 2011 and 2017. Progression-free survival (PFS) and overall survival were compared between patients on acid suppression therapy and those not on acid suppression therapy. Results A total of 70 patients were included. Patients on acid suppression therapy at capecitabine initiation (21%) had decreased progression-free survival versus those not on acid suppression therapy (HR 2.24, 95% CI 1.06-4.41, p = 0.035), after adjusting for disease severity and age. Acid suppression therapy use was associated with a numerical decrease in overall survival (HR 1.86, 95% CI 0.81-3.91, p = 0.14). In patients on any concomitant acid suppression therapy (25%), there was a decreased rate of progression-free survival (HR 6.21, 95% CI 2.56-14.32, p = 0.0001) but not overall survival (HR 1.64, 95% CI 0.68-3.54, p = 0.25) versus those without concomitant acid suppression therapy, after adjusting for age and disease severity. Conclusions Concurrent use of acid suppression therapy and capecitabine was associated with decreased progression-free survival, and there was a trend towards decreased overall survival. Due to the demonstrated potential of decreased efficacy, concurrent use of proton pump inhibitors or histamine 2 receptor antagonists should be avoided in colorectal cancer patients on treatment with capecitabine monotherapy.