Standard deviation of CT radiomic features among malignancies in each individual: Prognostic ability in lung cancer patients

Purpose: It was reported that individual heterogeneity among malignancies (IHAM) might correlate well to the prognosis of lung cancer; however, seldom radiomic study is on this field. Standard deviation (SD) in statistics could scale average amount of variability of a variable; therefore, we used SD of CT feature (Feature SD ) among primary tumor and malignant lymph nodes (LNs) in an individual to represent IHAM, and its prognostic ability was explored. Methods The enrolled patients who had accepted PET/CT scans were selected from our previous study (ClinicalTrials.gov, NCT03648151). The patients had primary tumor and at least one LN, and standardized uptake value of LN higher than 2.0 and 2.5 were enrolled as the cohort 1 (n = 94) and 2 (n = 88), respectively. Feature SD from the combined or thin-section CT were calculated among primary tumor and malignant LNs in each patient, and were separately selected by the survival XGBoost method. Finally, their prognostic ability was compared to the significant patient characteristics identified by the Cox regression. Results In the univariate and multivariate Cox analysis, surgery, target therapy, and TNM stage were significantly against OS in the both cohorts. In the survival XGBoost analysis of the thin-section CT dataset, none Feature SD could be repeatablely ranked on the top list of the both cohorts. For the combined CT dataset, only one Feature SD ranked in the top three of both cohorts, but the 3 significant factors in the Cox regression were not even on the list. Both in the cohort 1 and 2, C-index of the model composed of the 3 factors could be improved by integrating the continuous Feature SD ; furthermore, that of each factor was obviously lower than Feature SD . Conclusion Standard deviation of CT features among malignant foci within an individual was a powerful prognostic factor in vivo for lung cancer patients.