The neutrophil to albumin ratio as a predictor of pathological complete response in rectal cancer patients following neoadjuvant chemoradiation.

Pathological complete response (pCR) following neoadjuvant chemoradiotherapy (nCRT) and total mesorectal excision (TME), in patients with locally advanced rectal cancer, occurs in 15-27% of patients. Because blood cell counts and albumin are a direct indicator of the host environment, a response to nCRT might be predicted by these markers. This study was carried out to determine whether the neutrophil to albumin ratio (NAR) was predictive of pCR in veteran patients. Ninety-eight patients with rectal cancer who underwent standard nCRT, followed by TME were analyzed. Pre-nCRT and post-nCRT hematologic data were collected. Univariate and multivariate analyses were carried out. Kaplan-Meier curves were constructed with our primary endpoint of pCR. Male patients (99%), age 62.4±9.1 years, BMI=27.4±5.9 kg/m, rectal cancer distance from anal verge=7.1±4.5 cm (SD), interval between nCRT and TME=8 weeks, 55% patients=low anterior resection, 95% received 5-fluorouracil, and all patients received radiation, with 15% achieving a pCR. Univariate analysis showed that pre-nCRT carcinoembryonic antigen (15.8±45.1 vs. 3.5±5.3 ng/dl; P=0.002) and the pre-nCRT NAR (16.4±4.8 vs. 14.2±1.6; P=0.002) were associated with pCR. On multivariate analysis, pre-nCRT carcinoembryonic antigen (odds ratio=0.41, 95% confidence interval 0.22-0.77) and pre-nCRT NAR (odds ratio=0.76, 95% confidence interval 0.60-0.97) remained independent predictors of pCR. Overall survival between nonresponders and pCR patients at 1, 5, and 10 years was 96, 62, and 44% versus 93, 85, and 61%, P=0.13, and disease-free survival was 95, 60, and 47% versus 93, 85, and 61%, P=0.17; respectively. Our study shows that the pre-nCRT NAR is an independent predictor of pCR. These findings should be applied to other cohorts to determine its validity and reliability for use as a potential predictor of pCR.