Incidence of Disease Recurrence in Patients With Colon and Upper Rectum Adenocarcinoma Stage II and III Receiving Adjuvant Capecitabine Monotherapy: Do Number of Chemotherapy Cycles and Relative Dose Intensity of the Drug Play a Role?

Introduction/background: Adjuvant capecitabine monotherapy is an option for colon and upper rectum adenocarcinoma patients, providing they have stage II disease with an intermediate risk of recurrence, or stage III but they are above 70's or they have comorbidities. We wanted to examine whether the number of chemotherapy cycles and the relative dose intensity (RDI) of capecitabine monotherapy in the adjuvant setting are affecting disease recurrence.

Patients and methods: We included patients with completely resected stage II and III colon and upper rectum cancer who received adjuvant capecitabine monotherapy, from 2003 until May 2020. Patients with early relapse, i.e. during chemotherapy or within 6 months after the completion of adjuvant chemotherapy, and those with rectal cancer who received radiotherapy were excluded. Patients were divided into 3 groups based on the number of chemotherapy cycles received and the RDI. Group A included patients with ≤4 cycles of chemotherapy, group B patients with >4 cycles of chemotherapy and RDI ≤80%, and group C patients with >4 cycles of chemotherapy and RDI >80%. Study's endpoint, was recurrence free survival (RFS).

Results: Two hundred twenty six patients with stage II and III disease (164 and 62 respectively) were included. Sixteen, 166 and 44 were included in groups A, B and C respectively. After a median follow-up of 41 months, 21 patients (9,3%) had relapsed. Patients belonging to group C were found to have a trend for lower relapse rate compared to patients belonging to group A or group B.

Conclusion: Number of adjuvant capecitabine cycles and RDI might play a role in RFS in patients with stage II and III colon and upper rectum adenocarcinoma.