Patient characteristics
The study included a total of 286 patients. The median age was 67.5 (range, 28–93) years; 166 (58.0%) patients were male and 120 (42.0%) were female. T factor (the depth of tumor invasion) was 97 (33.9%) for T1 or T2, and 189 (66.1%) for T3 or T4. There were 106 (37.0%) cases with lymph node metastasis (N factor +) and 180 (62.9%) cases without lymph node metastasis (N factor -), GPS was 0, 1, 2 (196, 59, 31)(Table.1).
Determination of cut-off values
The ROC curve analysis results in 3yer-OS indicated that the most appropriate cutoff value for WBC was 6000. All patients were categorized into the high WBC group (WBC ≥6000; n=140, 49.0%) and a low WBC group( WBC<6000; n=146, 51.0%). Neu were classified into a high Neu group (Neu ≥4307; n=102, 35.6%) and a low Neu group (Neu<4307; n=184, 64.3%). Plt were classified into a high Plt group (Plt ≥194.6; n=43, 15.0%) and a low Plt group (Plt<194.6; n=243, 85.0%). Alb were classified into a high Alb group (Alb ≥3.9; n=161, 56.2%) and a low Alb group (Alb<3.9; n=125, 43.7%). Lym were classified into a high Lym group (lym ≥1606; n=96, 33.6%) and a low Lym group (Lym<1606; n=190, 66.4%). Chol were classified into a high Chol group (Chol ≥119; n=272, 95.1%) and a low Chol group (Chol<119; n=14, 4.9%). NLR were classified into a high NLR group (NLR ≥2.24; n=200, 70.0%) and a low NLR group (NLR<2.24; n=86, 30.0%). CAR were classified into a high CAR group (CAR ≥0.025; n=154, 53.8%) and a low CAR group( CAR<0.025; n=132, 46.2%)(Table.1).
Relationship between nutritional findings and overall survival
BMI (body mass index), lym (lymphocyte count), Alb (albumin), and Chol (cholesterol ) were used as nutritional indicators. The Kaplan-Meier curve of the OS in each item is shown in Fig.1. BMI and lymphocyte count were not significant factors. On the other hand, the low Alb group had a significantly worse overall survival rate than the high Alb group (p <0.0002). Similarly, Chol had significantly worse overall survival in the low Chol group than in the high Chol group (p <0.0001) (Fig.1).
Relationship between Inflammatory findings and overall survival
WBC (White blood cell count) , Neu (neutrophil count), Plt (platelets), and CRP (C-reactive protein) were used as inflammatory findings. The Kaplan-Meier curve of the OS in each item is shown in Fig.2. WBC were not a significant factor in the relationship for overall survival (p = 0.234). On the other hand, in the high Neu group, high Plt group, and high CRP group, the overall survival rate is significantly worse than that of the low Neu group, low Plt group, and low CRP group, respectively. It was (p = 0.017, 0.006, 0.0003) (Fig. 2).
Relationship between a combination model of known nutritional and inflammatory findings (NLR, CAR, PNI),tumor marker and overall survival
As known models, NLR and CAR were used as inflammation indicators, and PNI and GPS were used as nutritional indicators. NLR was not a significant factor in known models and overall survival (p = 0.051). CAR, PNI, and GPS were the indicators significantly associated with overall survival (p = 0.0001, p <0.0001, p = 0.006) (Fig. 3). CEA and CA19-9 were used as tumor markers, but CA19-9 was not a significant factor (p = 0.427). On the other hand, the overall survival rate was significantly worse in the high CEA group than in the low CEA group (p = 0.002).
Stratification using patient factors
Univariate analysis was performed using the COX proportional hazard model for the factors of BMI, Alb, Lym, Chol, WBC, Neu, Plt, and CRP in the OS. We decided to create a new risk model using five factors that were significant: Alb, Chol, Neu, Plt, and CRP (Table 3). The risk model was calculated by adding up the above-mentioned number of risk factors. The factors high group is positive. NIS counted that one positive was 1, 2 was 2, 3 was 3, 4 was 4, and 5 was 5. Kaplan-Meier survival curve was drawn by dividing into positive numbers (Fig. S1). As a result, 3 or more were defined as the high value group and 2 or less as the low value group. We named this new risk model NIS (nutrition inflammation status).
Kaplan–Meier Curve of NIS
Survival analyses were performed between low NIS group and high NIS group according to cutoff value of NIS. Statistically significant differences between the two groups were revealed by Kaplan-Meier curves on 3-year OS (P < 0.0001), indicating a potential prognostic value of NIS. The 3-year OS were 97.1% for the low NIS group, 77.3% for the high NIS group, respectively. A survival curve comparison of 3-year OS between the low NIS and high NIS groups showed a significantly poorer prognosis in the high NIS group (Fig.4).
Evaluation of NIS using C-index and AIC compared with T factor and N factor, CAR, PNI, GPS, CEA
T factor and N factor were used as oncological factors. Univariate and multivariate analysis was performed using the Cox proportional hazard model to determine the effects of T factor and N factor, CAR, PNI, GPS, CEA, and NIS on overall survival. As a result of multivariate analysis, only three significant factors, N factor PNI and NIS, were extracted (HR = 2.9, 95% confidence interval (CI):1.3-6.5, HR = 4.8, 95%CI:1.50-15.5, HR = 4.4, 95% CI: 1.5-12.9, respectively). As shown in Table2, C-indexes for the score (N factor, PNI, NIS) to predict OS were 0.636, 0.726 and 0.747, respectively. The AIC values of each index for OS were 277.85 for N factor, 265.32 for the PNI, 257.34 for the NIS. According to this comparison, NIS was the best goodness-of-fit, followed by N factor and GPS. NIS was the best model to reflect the prognosis after colorectal cancer surgery compared to CAR, PNI and GPS (table.2).