In this study, we included nearly five hundred patients with high grade osteosarcoma receiving surgical excision and collected their clinical features for calculating nutritional assessment indicators to explore the relationship between these indexes and different clinical outcomes. The GPS and CONUT score were evaluated as independent prognostic factors that high score on them indicated poor outcomes for OS significantly. The CONUT score was found significant association with duration of postoperative length of hospitalization from results of binary logistic regression analysis. A nomogram model on OS was built up to predict 3- and 5-year survival probability whose accuracy was evaluated by C-index, Brier score, and calibration curves. The calibration curves showed fitness between predicted and actual survival probability.
Osteosarcoma as a mesenchymal originated tumor represents the difference on peak incidence compared with other malignancies that geriatric population is not the only high-risk group but also the pediatric. The distributions of some patients’ demographic characteristics were different within two groups significantly. The location of primary malignancies was different that the tumors preferred to locate at axial line and its surrounds as age grows24. The standards of underweight, normal, overweight and obese depending on BMI were totally different between children and adult25, 26, so the pure comparison of value of BMI was lack of clinical practicability. Therefore, we categorized patients into different group depending on standards of the World Health Organization for each age range before statistical analysis. The development of the immune system was immature in children27 so the count of inflammatory indexes may differ from those of adults. Hence, we applied the ratio of correlated variables or adjusted the criteria of scoring for children that the inflammatory response reflects the nutritional situations28–30.
Our study identified GPS score as an independent prognostic factor that higher score of GPS predicted worse OS [HR (95% CI): 3.122 (1.982–4.918) versus 2.208 (1.014–4.804)]. This result was found in other researches of osteosarcoma base on Chinese population31. In that study, the GPS was divided into group, 0 and 1/2 that patients performed shorter survival time if CRP > 10 mg/L or albumin < 3.5 mg/L. In our study, we explored the increasing risk as the score of GPS elevating. There was a retrospective study showing the prognostic value of an innovative factor also based on C-reactive protein and albumin32 that may eliminate errors. The SII were calculated significantly just in the univariate Cox analysis. Nevertheless, their predicted value has been demonstrated by previous studies31, 33.
PNI as a continuous variable was the foundation of some innovative nutrition associated indicators like CONUT score. A previous study presented the prognostic value of PNI34 with the optimal cutoff point of 52.9 that may influence the further clinical practicability. We need a larger sample prospective study to estimate the predicted value of PNI. CONUT score was a modified index integrating serum albumin, lymphocyte and total cholesterol which was associated with the risk of malnutrition35, 36. In case of disturbance from the proportions of TG, HDL-c and LDL-c, we included them as confounding factors to avoid interference from them. The reliability of CONUT score was estimated superior than SII which only included indexes reflecting inflammatory response37, 38 in some kinds of carcinoma, but there have been no evidence to prove the advantages of CONUT scores compared with other inflammatory indicators. The prognostic value of CONUT score has been demonstrated in soft-tissue sarcoma39, 40 that the raised score of CONUT indeed improved risk of death.
Nomogram based on potential prognostic factors predicted patients’ long term survival probability and risk of duration of hospitalization. Extensive aspects about patients with osteosarcoma have been collected into the construction of nomogram41–43 including clinical, radiometric and genetic features. The validation for nomogram model was inevitable to assess the agreement between the predicted and actual survival probabilities that calibration curves in our study presented moderate consistency. Nevertheless, as for further practical application, we demand more adjustment of this model to decrease the bias and increase the accuracy.
There are several limitations existing in our study. Firstly, we were a single-center and retrospective study that the presence of recalling bias may decrease the actual efficacy of nutritional assessment tools which need to be assessed in a prospective study. Secondly, the preoperative nutritional status need a comprehensive evaluate with respect to the effects from diet habits, economic conditions and other factors which were omitted by in-hospital examination and inquiry of history easily. Thirdly, the bias existed during the recruitment of patients. Patients with high grade osteosarcomas who obtain alleviation from neoadjuvant chemotherapy may be more positive to receive surgery and other interventions. The different reflection of neoadjuvant chemotherapy may attribute to the individual nutritional status that there was bias in the baseline data which need justify.
Our study suggested prognostic value of nutritional assessment indexes including GPS and CONUT score on OS in patients with high grade osteosarcoma receiving surgical resection. These factors constructed a predicted model which was visualized and validated in this study. Appropriate preoperative interventions which could optimize patients’ nutrition associated indicators may improve prognosis on patients with high grade osteosarcoma receiving surgical excision.