(P 184) A SYSTEMATIC REVIEW ABOUT CLINICAL PROGNOSTIC MODELS FOR SARCOMAS

Objective: Current guidelines recommend the use of clinical prognostic models (CPMs) for therapeutic decision-making in soft-tissue sarcoma patients. While numerous CPMs were published over the last years, most of them are not used in clinical practice. A possible reason may be that the quality of developed and externally validated CPMs is unknown. Therefore, we aimed to describe and critically assess CPMs for sarcomas.

Methods: We performed a systematic review including all studies describing the development and/or external validation of a CPM for sarcomas. We searched the databases Medline, EMBASE, Cochrane Central and Scopus from inception until June 7th, 2022. Risk of bias was evaluated using PROBAST. Results were qualitatively summarised using descriptive statistics.

Results: 7,656 records were screened, of which 145 studies were eventually included, developing 182 and externally validating 59 CPMs. The most frequently modeled type of sarcoma was Osteosarcoma (43/182; 23.6%), and the most frequently predicted outcome was overall survival (81/182; 44.5%). The most used predictors were patient’s age (133/182; 73.1%) and tumor size (116/182; 63.7%). The median sample size was 635, however, no study provided an adequate sample size calculation. Univariable screening was used in 137 (75.3%) CPMs, only 7 (3.9%) CPMs were developed using pre-specified predictors based on clinical knowledge or literature. The median c-statistic of external validations was 0.72 (Interquartile Range [IQR] 0.68 - 0.75), the median area under the receiver operating characteristic curve was 0.77 (IQR 0.76 - 0.80). Calibration was only reported for 46 out of 59 (78.0%) externally validated CPMs. One-hundred-fifty (70.8%) CPMs were at high risk of bias, mostly due to high risk of bias in the analysis domain (85.8% were at high risk of bias).

Conclusion: We found that the majority (70.8%) of included models were at high risk of bias and suffered from poor methodological conduct. Therefore, use in routine clinical practice may not be recommended for most published CPMs of sarcomas. As most risk of bias stemmed from the analysis domain, researchers should consider published guidance on the development and external validation of CPMs. As only 32.4% of CPMs were externally validated, future research efforts should concentrate on external validation of existing CPMs rather than on the development of new ones.