Predicting tumor response after preoperative chemoradiation using clinical parameters in rectal cancer

Abstract

Aim: To evaluate the clinical parameters and identify a better method of predicting pathological complete response (pCR).

Methods: We enrolled 249 patients from a database of 544 consecutive rectal cancer patients who underwent surgical resection after preoperative chemoradiation therapy (PCRT). A retrospective review of morphological characteristics was then performed to collect data regarding rectal examination findings. A scoring model to predict pCR was then created. To validate the ability of the scoring model to predict complete regression.

Results: Seventy patients (12.9%) achieved a pCR. A multivariate analysis found that pre-CRT movability (P = 0.024), post-CRT size (P = 0.018), post-CRT morphology (P = 0.023), and gross change (P = 0.009) were independent predictors of pCR. The accuracy of the scoring model was 76.8% for predicting pCR with the threshold set at 4.5. In the validation set, the accuracy was 86.7%.

Conclusion: Gross changes and morphological findings are important predictors of pathological response. Accordingly, PCRT response is best predicted by a combination of clinical, laboratory and metabolic information.

Keywords: Downstaging; Preoperative chemoradiotherapy; Rectal cancer; Tumor regression; Validation.

Figures

Figure 1

Area under the receiver operating characteristic curve. A: Risk score in the test set was 80.5%, suggesting it was a reasonable predictor of complete regression (P < 0.001, 95% confidence interval = 0.723-0.886, n = 151); B: In the validation set, risk score was 87.5%. (P < 0.031, 95% confidence interval = 0.672-1.078, n = 151).