Role of Whole-Heart Cardiac Dose (WH-CD) on OS in Non-Small Cell Lung Cancer (NSCLC) Patients (Pts) Receiving Post-Operative Radiotherapy (PORT)

• Published in: International journal of radiation oncology, biology, physics Vol. 120; no. 2; p. e15
• Main Authors: Cruz-Chamorro, R.J., Bryant, J.M., Dilling, T.J.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.2024
• ISSN: 0360-3016
• DOI: 10.1016/j.ijrobp.2024.07.1810

Lung-ART found that PORT did not improve OS in N2+ NSCLC pts. However, they implied that WH-CD was likely relevant, though no analysis was provided. Consequently, we evaluated the role of WH-CD on OS in pts receiving PORT. We identified consecutive patients with pathologic stage I-IIIB NSLC treated with PORT from 9/2009 to 6/2022 at a multi-site tertiary cancer center from our prospectively maintained database. We captured WH-CD dosimetry every 5 Gy, minimum and mean doses, and D0.03cc. To understand the role of stage/tumor bulk on WH-CD and OS, we ran the analysis twice: 1) all pts, including N2- pts treated for positive margins (All); and 2) pts treated for N2 disease (N2+). Cox proportional hazard testing was performed for univariable analysis (UVA) and multivariable analysis (MVA). To correct for multiple comparisons in MVA, we used Benjamini-Hochberg procedure. We identified 177 consecutive patients with stage IA-IIIB NSLC (N2+ = 126) treated with PORT to a median dose of 50 Gy (range 50-70 Gy). Median OSALL was 57.2 months (N2+ = 52.1). 25% and 19% of All had R1 and R2 resections, respectively. IMRT was significantly associated with larger PTV (p = 0.0094) and higher heart mean dose (p = 0.0036). Multi-station N2 disease was not associated with OS (p = 0.9). Involvement of hilar/N2 nodes and the number of N2+ stations were significantly associated with higher heart mean doses. In UVAAll, all cardiac dose factors were significantly associated with worse overall survival (OS). Conversely, on UVA of N2+, all fell away except for V50, which just met statistical significance (see Table). On MVA of N2+, well-differentiated cancers were significantly associated with a worse OS (q = 0.017). Heart volume was nearly significant (q = 0.070) as well as R2 resection status (q = 0.095). No WC-CD variables were significant. WH-CD is a surrogate for tumor stage/bulk which essentially falls out of significance in the N2+ cohort in UVA (absent in MVA). This implies that WH-CD is a surrogate for stage/bulk in these pts and is not an independent risk factor.