Purpose: We set out to explore the probability of MRI-detected extramural vascular invasion (mr-EMVI) before chemoradiation to predict responses to chemoradiation and survival in stage T3 rectal cancer patients.
Methods: A total of 100 patients with T3 rectal cancer who underwent MRI examination and received neoadjuvant chemoradiation and surgery were enrolled. The correlation between mr-EMVI and other clinical factors were analyzed by chi-square. Logistic regression model was performed to select the potential factors influencing tumor responses to neoadjuvant chemoradiation. A Cox proportional hazards regression model was performed to explore potential predictors of survival.
Results: The positive mr-EMVI result was more likely to be present in patients with a higher T3 subgroup (T3a+b = 7.1% vs. T3c+d = 90.1%, P < 0.001) and more likely in patients with mesorectal fascia involvement than in those without MRF (65% vs. 38.8%, P = 0.034). Compared with mr-EMVI (+) patients, more mr-EMVI (-) patients showed a good response (staged ≤ ypT2N0) (odds ratio [OR], 3.020; 95% confidence interval [CI], 1.071-8.517; P = 0.037). In univariate analysis, mr-EMVI (+) (hazard ratio [HR], 5.374; 95% CI, 1.210-23.872; P = 0.027) and lower rectal cancers (HR, 3.326; 95% CI, 1.135-9.743; P = 0.028) were significantly associated with decreased disease-free survival. A positive mr-EMVI status (HR, 5.727; 95% CI, 1.286-25.594; P = 0.022) and lower rectal cancers (HR, 3.137; 95% CI, 1.127-8.729; P = 0.029) also served as prognostic factors related to decreased disease-free survival in multivariate analysis.
Conclusion: The mr-EMVI status before chemoradiation is a significant prognostic factor and could be used for identifying T3 rectal cancer patients who might benefit from neoadjuvant chemoradiation.