Topology based radiomic feature derived from persistent homology predicts survival in non-small cell lung cancer patients treated with SBRT

IntroductionImproved survival prediction and risk stratification in non-small cell lung cancer (NSCLC) would lead to better prognosis counseling, adjuvant therapy selection, and clinical trial design. We propose the PHOM (persistent homology) score, the radiomic quantification of solid tumor topology, as a solution. MethodsPatients diagnosed with stage I or II NSCLC primarily treated with stereotactic body radiation therapy (SBRT) were selected (n = 554). The PHOM score was calculated on each patients pre-treatment CT scan (10/2008 to 11/2019). PHOM score, age, sex, stage, Karnofsky Performance Status (KPS), Charlson-Comorbidity Index (CCI), and post-SBRT chemotherapy were predictors in the Cox proportional hazards models for overall and cancer-specific survival. Patients were split into high and low PHOM score groups compared using Kaplan-Meier curves for overall survival and cumulative incidence curves for cause specific death. Finally, we generated a validated nomogram to predict overall survival, publicly available at https://eashwarsoma.shinyapps.io/LungCancerTDATest/. ResultsPHOM score was a significant predictor for overall survival (HR: 1.17, 95% CI: 1.07-1.28) and was the only significant predictor for cancer-specific survival (1.31, 95% CI: 1.11-1.56) in the multivariable Cox model. The median survival for the high PHOM group was 29.2 months (95% CI: 23.6-34.3), which was significantly worse compared to the low PHOM group (45.4 months, 95% CI: 40.1-51.8, p < 0.001). The high PHOM group had a significantly greater chance of cancer-specific death at post treatment month 65 (0.244, 95%CI: 0.192-0.296) compared to the low PHOM group (0.171, 95% CI: 0.123-0.218, p = 0.029). ConclusionsThe PHOM score is associated with cancer-specific survival and predictive of overall survival. Our developed nomogram can be used to inform clinical prognosis and assist in making post-SBRT treatment considerations.