Initial report on feasibility of PET/CT-based image-guided moderate hypofractionated thoracic irradiation in node-positive non-small cell lung Cancer patients with poor prognostic factors and strongly diminished lung function: a retrospective analysis

BACKGROUND: To determine the feasibility of PET/CT-based image-guided moderate hypofractionated thoracic irradiation (Hypo-IGRT) in locally advanced node-positive non-small cell lung cancer patients with highly compromised pulmonary function. METHOD: Eight highly-selected and closely monitored patients with highly diminished pulmonary function (FEV1 ≤ 1.0 L and/or DLCO-SB ≤ 40% and/or on long-term oxygen therapy) were treated with Hypo-IGRT. Planning was based on 18F-FDG-PET/CT and 4D-CT in the treatment position. Hypo-IGRT was delivered to a total dose of 45 Gy (ICRU) in 15 daily fractions under strict image-guidance. Vital capacity (VC), forced expiratory volume in 1 s (FEV1), and single-breath diffusing capacity of the lung for CO (DLCO-SB) were analyzed prior to, 3 and 6 months after Hypo-IGRT. RESULT: Eight patients with stage IIIA-C NSCLC (8th TNM Ed.) completed Hypo-IGRT. The median follow-up was 29.4 months. The median age was 64 years. Four, three and one patient(s) presented with COPD GOLD IV, III and II, respectively and 5 patients (63%) were on long-term oxygen therapy. The median PTV was 226.9 cc (range: 100.17–379.80 cc). Median PFS and OS were 19 and 34.3 months. The 6 months and 1-year OS rates were 100, 87.5%, respectively. The 6- and 12- months PFS rates were 87.5 and 52.5%. Three patients developed local failure. Median initial VC, FEV1 and DLCO-SB was 1.69 L/64.8% predicted (range: 1.36–2.66 L/33–80%), 1 L/39.4% predicted (range:0.78–1.26 L/28–60% predicted) and 33.3% (range: 13.3–54%) predicted, respectively. Median values for VC, FEV1, DLCO-SB 3 and 6 months after Hypo-IGRT were 2.05 L/56.35% predicted (range: 1.34–2.33 L/47–81.5%), 1.08 L/47.5% predicted (range: 0.74–1.60 L/30.8–59.59%), 38.55% (range: 24–68%) and 1.64 L/66% predicted (range: 1.41–2.79/35.5–75.5%), 1.0 L/47% predicted (range: 0.65–1.28 L/24.5–54.10%), 31% (range: 27–43%), respectively. Mean lung dose was 9.4 Gy (range: 5.3–11.6 Gy) and V20 for both lungs was 15% (range: 6–19%). Mean esophageal dose was 12.76 Gy (range: 2.1–26.7 Gy). There was no case of grade 2 or higher radiation pneumonitis. Four patients developed grade 2 radiation esophagitis. CONCLUSION: Hypo-IGRT can be considered for individual and closely monitored patients with locally advanced node-positive NSCLC with highly compromised pulmonary function. No severe pulmonary toxicity and significant decline of pulmonary function parameters was observed in our cohort. Currently, this protocol is being assessed in an ongoing single-centre prospective study.