Association of radiation dose intensity with overall survival in patients with distant metastases

• Published in: Cancer medicine (Malden, MA) Vol. 10; no. 22; pp. 7934 - 7942
• Main Authors: Kao, Johnny, Farrugia, Mark K., Frontario, Samantha, Zucker, Amanda, Copel, Emily, Loscalzo, John, Sangal, Ashish, Darakchiev, Boramir, Singh, Anurag, Missios, Symeon
• Format: Journal Article
• Language: English
• Published: United States John Wiley & Sons, Inc 01-11-2021; John Wiley and Sons Inc; Wiley
• Subjects: Adult; Aged; Aged, 80 and over; Albumin; Cancer therapies; Clinical Cancer Research; Drug dosages; Electronic health records; Female; Gender; Hospitalization; Humans; Liver; Lymphatic system; Lymphocytes; Male; Medical prognosis; Medical records; Metastases; Metastasis; metastatic; Middle Aged; Neoplasm Metastasis; Neoplasms - mortality; Neoplasms - radiotherapy; Neutrophils; Oncology; patient selection; Patients; Population studies; Prognosis; Prostate; Radiation therapy; radiotherapy; Radiotherapy Dosage - standards; Regression analysis; Survival; Survival Analysis; Tumors; Young Adult; radiotherapy; patient selection; metastatic; survival
• ISSN: 2045-7634; 2045-7634
• DOI: 10.1002/cam4.4304

Background
Patients with metastatic cancer referred to radiation oncology have diverse prognoses and there is significant interest in personalizing treatment. We hypothesized that patients selected for higher biologically equivalent doses have improved overall survival.
Methods
The study population consists of 355 consecutive adult patients with distant metastases treated by a single radiation oncologist from 2014 to 2018. The validated NEAT model was used to prospectively stratify patients into four distinct cohorts. Radiation dose intensity was standardized using the equivalent dose in 2 Gy fractions (EQD2) model with an α/β of 10. Radiation dose intensity on survival was assessed via Cox regression models and propensity score match pairing with Kaplan–Meier analysis.
Results
The median survival was 9.3 months and the median follow‐up for surviving patients was 18.3 months. The NEAT model cohorts indicated median survivals of 29.5, 11.8, 4.9, and 1.8 months. Patients receiving an EQD2 of ≥40 Gy had a median survival of 16.0 months versus 3.8 months for patients receiving an EQD2 of <40 Gy (p < 0.001). On multivariable analysis, performance status, primary tumor site, radiation dose intensity, albumin, liver metastases, and number of active tumors were all independent predictors of survival (p < 0.05 for all). Propensity score matching was performed for performance status, albumin, number of active tumors, primary tumor site, and liver metastasis, finding higher EQD2 to remain significantly associated with improved survival within the matched cohort (p = 0.004).
Conclusion
Higher radiation dose intensity was used in patients with better prognosis and was associated with improved survival for patients with metastatic disease.
Personalized radiotherapy treatment options for patients with metastatic is of significant interest and prompted investigation into higher biological equivalent doses to see if there was increased survival. Higher dose intensity was used for patients with better progresses and was associated with improved survival with metastatic diseases.