Progression-free survival in patients with metastatic colorectal cancer treated with maintenance therapy with bevacizumab adjusted by sideness in a third level hospital in Mexico City

Maintenance therapy is a standard practice in metastatic colorectal cancer, phase III trials has shown an impact in PFS and OS without an increase of toxicity. Sidedness of primary tumor is an independent prognostic and predictive factor for the combination of chemotherapy and anti - VEGF treatment. In this study we present the results of the treatment with bevacizumab in Mexican population adjusted by sideness.

We made a retrospective, longitudinal, observational study of patients diagnosed with metastatic colorectal adenocarcinoma treated with chemotherapy and bevacizumab as maintenance therapy between 2016 and 2021 at Hospital de Oncología Centro Médico Nacional Siglo XXI in Mexico City. A descriptive analysis was carried out to characterize the study population, for quantitative variables measures of central tendency and dispersion were determined. For categorical variables, absolute frequencies and percentages were expressed Progression-free survival was estimated using the Kaplan-Meier method.

During the study period, 245 patients were treated with chemotherapy and bevacizumab as maintenance therapy. A greater number of male patients (61%) was documented. The relationship of the primary site showed that 76% of the patients presented involvement of the left colon, while 24% presented a tumor in the right colon. Most of the patients (63%) had metastatic disease at diagnosis, while the rest had recurrent disease. The median progression-free survival was 15 months. After adjusting for laterality, it was observed that the median progression-free survival for tumors on the right side was 16 months and for tumors on the left side it was 15 months (p=0.219). Clinical response to primary-line chemotherapy was a significant predictor of survival, with complete response patients (7%) achieving a median PFS of 36 months, while patients with stable disease (61%) achieved 13 months.

The median progression-free survival achieved in our study was 15 months, which is higher than that reported in the pivotal CAIRO-3 study (median 11.5 months). The response rate achieved (39.1%) was similar to that reported in the 44.8% approval study of bevacizumab (Hurwitz), however with current schemes response rates of the order of 50-55% are achieved. We did not observe significant differences according to laterality, with the median PFS being 15 months in both right and left tumors.

The authors.

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All authors have declared no conflicts of interest.