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.