Factors associated with complete clinical response after neoadjuvant therapy in locally advanced rectal cancer: A Mexican retrospective study

Abstract

BACKGROUND

Treatment for rectal cancer varies widely among populations due to differences in tumor biology, access to treatment and care systems. Global responses to standard therapies are heterogeneous and data from Latin American populations, particularly Mexican patients, are scarce.

AIM

To assess complete clinical response (cCR) rates, local recurrence, and associated factors in a Mexican neoadjuvant therapy cohort.

METHODS

A retrospective observational study included 101 clinical stage II-III rectal cancer patients with neoadjuvant therapy. The primary endpoint was cCR, and pathological complete response (pCR) was assessed among patients who underwent surgery. An overall complete response rate (cCR or pCR) is reported descriptively. An exploratory univariate analysis was performed to evaluate factors associated with cCR. Response durability and local recurrence-free survival were estimated using the Kaplan-Meier method.

RESULTS

The cCR was achieved in 14.9% (n = 15) of the cohort, while overall complete response (cCR or pCR) was observed in 19.8% (n = 20). Among complete responders, 25% (n = 5) had pCR confirmed after surgery. During follow-up, two local recurrences occurred among patients managed with watch-and-wait (2/15; 13.3%), both within the first 16 months. In exploratory univariate analysis, tumor size was inversely associated with the likelihood of achieving cCR (OR = 0.77 per centimeter; 95%CI: 0.61-0.96; P = 0.028).

CONCLUSION

Neoadjuvant therapy achieved 19.8% of cCR, mostly managed by watch-and-wait. Tumor size predicted cCR. These findings support structured surveillance and warrant prospective studies for better predictors.

Keywords: Rectal neoplasms; Neoadjuvant therapy; Clinical complete response; Pathologic complete response; Watch-and-wait

Core Tip: Recognizing the high prevalence of locally advanced rectal cancer at presentation in the Mexican population, we assessed 101 patients with clinical stage II-III rectal cancer who underwent neoadjuvant therapy and found, consistent with global literature, that approximately 20% of patients achieved a complete response, while tumor size was inversely correlated with the probability of achieving a complete clinical response.