T102 - Response Prediction to Neoadjuvant Chemoradiotherapy in Rectal Cancer Based in Systemic Inflammatory Markers (NLR, PLR and LMR)

Purpose/Background: Patients with rectal cancer who receive neoadjuvant chemoradiotherapy(nCRT) may achieve complete response(CR). There is intense search for clinical, radiological, or laboratory factors capable of predicting response to nCRT.
The neutrophil-to-lymphocyte ratio(NLR), platelet-to-lymphocyte ratio(PLR), and lymphocyte-to-monocyte ratio(LMR) are associated with cancer-inflammation interactions and data suggests that these ratios could indicate the patient's "inflammatory status", possibly linked to tumoral behaviour.
The present study aimed to evaluate the response prediction to nCRT in rectal cancer patients, based on NLR, PLR and LMR.

Methods/Interventions: This single-institution retrospective study evaluated patients with rectal cancer who undergone curative intent treatment for biopsy-proven rectal cancer; inclusion criteria considered patients with initial staging T2-4NxM0 or T (any) N + M0 elected to nCRT.
All patients underwent radical treatment consisting of nCRT followed by radical surgery with total mesorectal excision (TME) or clinical observation in selected cases of documented cCR. Weekly multidisciplinary meetings determined the neoadjuvant treatment strategies.
Clinical, laboratory, and pathological data were obtained from patients’ electronic records.
Patients were stratified according to pathological tumor response grade(TRG) to nCRT:
0: Complete response or persistent cCR, 1: Almost complete response, 2: Partial response, 3: No response.

Results/Outcomes: Five hundred and nine patients were included. After exclusions, data from 396 patients were analyzed.
Two hundred and sixteen patients (54.5%) were male, with a mean age of 60.5 years (± 12.2 years); 379 patients (95.7%) underwent radical surgery, and the remaining 17 (4,3%) were considered to have persistent cCR and elected for observation (watch and wait program).
The average time between the end of the nCRT and surgery was 15 weeks (± 3.7 weeks).
Regarding anatomopathological findings, 168 patients (44.4%) had ypT3 and 261 (68,9%) had ypN0 among the valid cases, and the most frequent stages were 2 and 3, with 101 (25.6%) and 113 patients (28.6%), respectively.
The TRG score categories were considered to stratify the study of the other variables. Ninety three patients (23,5%) were classified as TRG 0, 70(17,7%) as TRG 1, 133 (33.6%) as TRG 2 and 100 (25.3%) as TRG 3.
Incomplete responders(TRG 1-2-3) were associated with a higher NLR(p < 0.001), PLR(p=0.002), CEA (p < 0.001) and male sex (p=0.021).
Complete responders (TRG 0) were associated with a higher number of comorbidities (p=0.001), hemoglobin level (p=0.049), LMR(p < 0.001), use of antihypertensive drugs (p=0.012), and platelet antiaggregant/anticoagulant drugs(p=0.045).
To estimate incomplete response: NLR >2.08 - RR: 2.30(95%CI:1.60-3.31); PLR >129.36 - RR: 1.79(95%CI:1.25-2.05) and LMR >2.67 - RR: 0.42(95%CI:0.26-0.66).
In a multiple linear model, NLR>2.08 was independently associated with incomplete response(RR=1.19[95%CI:1.07-1.28],p=0.001); AUC:0.659(95%CI:0.599- 0.718).

Conclusion/Discussion: NLR, PLR, and LMR are predictors of response to nCRT in patients with rectal cancer.
NLR > 2.08 is a predictive factor for an incomplete response to nCRT.
The identification of the good and bad responders can collaborate to treatment individualization in order to obtain the best possible treatment strategy for each patient.
These findings add a low-cost and widely available tool for rectal cancer management.