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Pathologic complete response to neoadjuvant chemoradiation as a predictor of survival in Latin American patients with rectal cancer
Background
Curative surgery after neoadjuvant chemoradiotherapy is the gold-standard treatment of patients with locally advanced rectal cancer. Pathologic complete response (pCR) after resection is observed in 15%-20% of cases and has been described as the strongest prognostic factor of low rate of recurrence and a long-term overall survival. Nevertheless, the correlation of pCR and other clinicopathological features remains unclear. The aim of this study was to assess the impact of pCR on disease free survival and overall survival of Latin American patients with locally advanced rectal cancer treated in the National Cancer Institute.
Methods
Retrospective, observational study. Included patients diagnosed with locally advanced rectal adenocarcinoma (LA-RC) and treated at the National Cancer Institute between 2016 and 2020. Statistical analysis required: X2 and t test, Kaplan Meier, Log Rank and Cox Regression. Statistical significance differences were assessed when p was bilaterally < 0.05.
Results
A total of 225 patients treated with chemoradiotherapy neoadjuvant were included in the analysis. The 51% (n= 114) were female with a median age of 58 (20-85) years old. Regarding comorbidities, the 20%(n=43) were previously diagnosed with type-2-diabetes, the 16% (n=35) with systemic arterial hypertension, 48% (n= 107) overweight and 17% (n=39) obesity. Tumor location distribution was 10%(n=23) upper, 22%(n=49) medium, and 68%(n=153) lower rectum. The 75% (n=168) patients had moderated differentiation grade, and the mean tumor size was 6.4 cm (3.3±). For this analysis, population was divided in 2 groups: 1) pCR (n=60) and 2) Non-pCR (n=165). Among patients with non-PCR, mean lymph nodes resected was 15.23 (14.0±) of them, the mean positive nodes were 1.27 (4.39±) (p=0.001), and the 11%(n=18) had R1 surgical margins (p=0.003) . Recurrence rate after surgical resection was 7% (n=4) and 27% (n=44) in pCR and non-pCR respectively (p=0.001). Besides, most patients had distant recurrence for both groups (p=0.282). Disease free survival (DFS) and Overall survival (OS) analysis were conducted comparing both groups. Five-year-DFS rates were 91% for pCR versus 65% for non-pCR group (p=0.003; HR 0.21, 95%CI 0.07-0.59). Additionally, Five-year-OS rates were 90% versus 70% for pCR and non-pCR respectively (p=0.047; HR 0.29, 95%CI 0.09-0.98). At Multivariate analysis for DFS, surgical margins (p=0.023; HR 0.34, 95%CI 0.13-0.86) and pCR (p=0.03; HR 0.31, 95%CI 0.11-0.89) remained as independent predictors of DFS. Furthermore, at multivariate analysis of OS, pCR did not remained predictor of OS, only recurrence site (p=0.004; HR 1.65, 95%CI 1.17-2.32).
Conclusions
The impact of pCR remains relevant for outcome of locally advanced rectal cancer patients, with statistical differences in DFS and OS rates. Besides, pCR remained as independent predictor factor of PFS. This study supports the need of total neoadjuvant treatment to increase pPCR in LA-RC patients. Additionally, to our knowledge, this is one of the first studies analyzing the correlation between pCR and clinicopathological features of Latin American patients with LA-RC.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosures
C. Perez Plascencia: Honoraria (Institution): Instituto Nacional de cancerologia, Universidad Nacional Autonoma de Mexico. All other authors have declared no conflicts of interest.
