4741 - Real world data on adjuvant chemotherapy for high-risk stage II colorectal cancer – the role of tumor side

Background

Although controversial, available data suggest a possible benefit of adjuvant chemotherapy (CT) for high-risk stage II colorectal cancer (CRC). The impact of sidedness and adjuvant CT duration in this setting is uncertain. We aimed to evaluate the outcomes of high-risk stage II CRC patients (pts).

Methods

We performed a single-center retrospective analysis of pts with stage II CRC treated between Jan/2011 and Dec/2018. Study data were collected using REDCap^®. We compared overall survival (OS) and recurrence-free survival (RFS) of high-risk pts who received or not adjuvant CT. High-risk was at least one of the following: T4 stage, < 12 lymph nodes resection, emergency presentation, lymphovascular invasion, perineural invasion or poor differentiation. CT consisted of fluoropyrimidine alone. Pts with known microsatellite instability were excluded. Survival analyses were estimated with the Kaplan-Meier method and compared by log-rank test. Prognostic factors, including tumor side and duration of CT, were evaluated with Cox regression.

Results

1047 pts with stage II CRC were evaluated, and 540 had high-risk criteria.157 (29%) pts had right tumor and 352 (65.2%) left. 335 (62%) received adjuvant CT. Duration of CT was 3 – 6 months for 305 (91%) pts. Pts who received adjuvant CT had superior RFS and OS in comparison with those who did not receive adjuvant CT (5-year RFS: 75.5% vs 65.6%, HR 0.58, 95% CI 0.41 – 0.82, P = 0.002; 5-year OS: 87.7% vs 76.1%, HR 0.46, 95% CI 0.28 – 0.73, P = 0.001). No difference in RFS and OS was observed according to tumor side (left vs right, HR 0.86, 95% CI 0.56 – 1.31, P = 0.494). Prognostic factors in multivariable analysis were: T4 stage (HR 2.29, P = 0.002), emergency presentation (HR 2.44, P = 0.001), perineural invasion (HR 1.84, P = 0.025), and adjuvant CT (HR 0.45, P = 0.002).

Conclusions

Adjuvant CT was associated with improved RFS and OS in patients with high-risk stage II CRC, with a total gain of 11.6% in 5-year OS. Tumor side did not influence the outcomes in this study.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Camila Soares Araujo de Carvalho.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.