Study design and population
All patients were from the Investigation on Nutrition Status and Clinical Outcome of Common Cancers (INSCOC) project of China (Registration Number: ChiCTR1800020329), which prospectively enrolled patients with cancer hospitalized at more than 40 medical centers in China between June 2010 and December 2017. The inclusion criteria for this study were as follows: 1) Histopathologically confirmed cancer; 2) Complete, available clinicopathological and serological data; 3) Age 18 years or older; 4) Voluntarily participation in this study. The exclusion criteria were as follows: 1) Admission time < 24 h; 2) Severe infection and acute inflammation, 3) Continuous use of anti-inflammatory drugs within the past 6 months; 4) Acquired immunodeficiency syndrome; 5) Unwillingness or inability to participate because of cognitive impairment. This study strictly complied with the Declaration of Helsinki during the research process and was approved by the ethics committees of all participating institutions. All participants signed written informed consent to participate in this study.
Data collection and definitions
Baseline clinicopathological variables including demographic characteristics (sex, age, height, and weight), family history of cancer, lifestyle factors (smoking and drinking), comorbidities (hypertension and diabetes), and disease information (tumor type, pathological stage, and treatment methods). Pathological stage was defined using the 8th edition of the TNM classification system of the American Joint Committee on Cancer staging system. Blood samples were collected after fasting for 10 h (before treatment). Blood tests included white blood cell (WBC), neutrophil, lymphocyte, platelet, red blood cell (RBC), hemoglobin, albumin, CRP levels, and blood glucose. In this study, biomarkers containing CRP or those previously thought to be associated with inflammation were defined as systemic inflammation biomarkers, including lymphocyte-to-CRP ratio (LCR), CRP-to-albumin ratio (CAR), modified geriatric nutrition risk index (mGNRI), neutrophil-to-lymphocyte ratio (NLR), systemic inflammation index (SII), lymphocyte-CRP score (LCS), glucose-to-lymphocyte ratio (GLR), and platelet-to-lymphocyte ratio (PLR). Biomarkers containing albumin or those previously thought to be associated with nutrition were defined as nutrition biomarkers, including the advanced lung cancer inflammation index (ALI), prognostic nutritional index (PNI), nutritional risk index (NRI), geriatric nutritional risk index (GNRI), albumin-to-globulin ratio (AGR), and the controlling nutritional status score (CONUT). These biomarkers were calculated using formulas reported in previous studies [25,26,27,28]. The formula of those indicators is presented in Table S1.
Construction of the INS model
Among these inflammation biomarkers, the LCR and CAR were the most effective biomarkers in prognostic evaluation of patients with cancer, with C-indexes of 0.652 (0.640, 0.665) and 0.649 (0.636, 0.661), respectively. Among these nutrition biomarkers, the ALI and NRI were the most effective biomarkers in prognostic evaluation of patients with cancer, with C-indexes of 0.643 (0.630, 0.655) and 0.623 (0.610, 0.636), respectively (Fig. S1). In addition, the Pearson test showed that the correlation between these biomarkers was relatively small (Fig. S2). Based on the above analysis, we selected the top two systemic inflammation and nutrition biomarkers for further analysis. The optimal stratification method determined the optimal threshold for LCR, CAR, ALI, and NRI were 2813, 0.165, 33, and 94, respectively (Fig. S3). Subsequently, we constructed a novel inflammation nutrition score (INS) system based on these inflammation and nutrition biomarkers. The process diagram of INS system construction and risk stratification was developed as follows: low LCR (< 2813), high CAR (≥ 0.165), low ALI (< 33), and low NRI (< 94) were scored as 1, and the remaining values were scored as 0. All scores were added together, and the final risk stratification was categorized into five groups (INS 1–5) according to the scores (e.g., score of 0 = INS value of 1) (Fig. 1).
Follow-up and outcomes
Medical professionals performed follow-up evaluations (including face-to-face outpatient follow-up and telephone follow-up) until the last follow-up date (October 30, 2020) or the date of death from any cause. The primary outcome was all-cause mortality, defined as the period from the date of pathologic diagnosis to the date of death, study withdrawal, or last follow-up. Secondary outcomes included physical status, which was assessed by the Karnofsky performance status questionnaire (KPS); nutritional status, which was assessed by the Patient-generated Subjective Global Assessment (PG-SGA); quality of life, which was assessed by the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire version 3.0 (EORTC QLQ-C30); cachexia, which was diagnosed according to the internationally recognized diagnostic criteria for cachexia proposed by Fearon et al. in the International Consensus on Cachexia in 2011[29]; and short-term outcome, which was defined as the patient’s outcome 90 days after treatment.
Statistical analysis
Continuous variables were expressed as means and standard deviations (SD) or medians and interquartile differences. Categorical variables were expressed as frequencies and proportions. The Chi-square or Fisher’s exact test was used for comparison of categorical variables between groups, while the Mann–Whitney U or unpaired student’s T-test was used for continuous variables. To avoid the influence of collinearity between the various biomarkers, we used LASSO Cox regression with “glmnet” package, and Pearson’s test to eliminate biomarkers with large collinearity. Subsequently, Harrell concordance statistics (C-statistics), continuous net reclassification improvement (cNRI), integrated discrimination improvement (IDI), and the time-dependent area under the receiver operating characteristic curve (AUC) were calculated to compare the predictive capacity of biomarkers. Optimal stratification was used to solve the threshold of continuous biomarkers through log-rank statistics. Similar to previous research [30, 31], restricted cubic spline (three knots) regression with “rms” package was used to assess the relationship between continuous biomarkers and survival of patients with cancer. Survival curves were presented using the Kaplan–Meier method and log-rank test to evaluate the difference in survival rates between groups. The Cox proportional hazards model was used to investigate the association between potential biomarkers and all-cause mortality, under the model of independent effects. Meanwhile, we also assessed the dose–response relationship between the primary variable and survival to test robustness. Subsequently, we performed an internal randomization to validate the effectiveness of the model based on computer-generated random numbers in a 7:3 ratio. Univariate and multivariable logistic regression models were used to assess associations between the INS model and secondary outcomes. Model a did not adjust for any confounding factors. Model b adjusted for age, sex, BMI, TNM stage, tumor type, surgery, radiotherapy, chemotherapy, hypertension, diabetes, smoking, drinking, family history. These adjusted variables included clinicopathological information affecting the prognosis of cancer patients. All statistical analyses were performed using R, version 4.0.5 (http://www.R-project.org).