Can Haematology Blood Tests at Time of Diagnosis Predict Response to Neoadjuvant Treatment in Locally Advanced Rectal Cancer

Background: Outcomes in locally advanced rectal cancer are improved by neoadjuvant therapy followed by surgical resection. Some patients respond completely to preoperative treatment. Therefore, predicting the pathological response to preoperative therapy is of clinical importance. Accurate prediction would allow for tailored approaches to neoadjuvant therapy. Methods: All patients undergoing resection of rectal adenocarcinoma after neoadjuvant therapy between 2006 and 2015 were included in this cohort study. Patients were identified from a prospectively collected database and data were supplemented retrospectively with full blood count at diagnosis. Specimens resected following neoadjuvant therapy were graded according to pathological response. Follow-up data was obtained from the national registry. The primary outcome was complete pathological response. Results: Of 330 patients, 71 (21.5%) responded completely to preoperative therapy. Median age was 66 and 65% were male (n = 215). White cell count (WCC) was the most predictive marker, for predicting pCR; area under the curve (AUC) 0.666. This was higher than neutrophil/platelet ratio (AUC 0.652) or neutrophil/lymphocyte ratios (AUC = 0.437). Kaplan-Meier survival analysis showed those patients with WCC > 8 had poorer survival than those with WCC < 8 (p = 0.009). Conclusion: Routinely collected haematology samples at the point of diagnosis can assist in predicting for complete response to neoadjuvant therapy. Although novel biomarkers will have a greater predictive value, this clinically available value test could help to assist in risk stratification of patients using routinely collected laboratory tests.