Outcomes of Elderly and Very Elderly Patients Treated By Dose-Adapted SABR for Early Stage Non-Small Cell Lung Cancer or Lung Oligometastatic Disease

Abstract

Stereotactic ablative radiotherapy (SABR) is increasingly used in elderly patients(pts) with inoperable lung tumour. Studies suggest that elderly pts have reduced tolerance to SABR and might have higher risk of significant toxicities. Our objectives were to retrospectively evaluate treatment completion and clinical outcomes of dose adapted lung SABR (L-SABR), in large cohort of patients 75 and older, treated in a single community based practice. From 04/08 to 09/15, 215 pts, aged 75-93(median 81), received SABR for lung tumours in our institution. IMRT based - SABR was delivered using Varian Trilogy TX with high definition MLC and on-board image guidance. Respiratory motion management was used in all pts. Dose fractionation was risk adapted: 60 Gy/3 (26 pts, 12%), 60 Gy/5 (82 pts, 38%), 48 Gy/4 (9 pts,4.2%), 60Gy/8 (88 pts, 41%), and other (10 pts, 4.6%), delivered in 2-3 weekly treatments. Treatment completion, local control (LC), overall survival (OS) and treatment related toxicities (CTCAE v.4.0) were evaluated. Data was censored at the last known follow-up. Descriptive statistics and Kaplan Meier methods were used (IBM SPSS 20, Chicago, IL). Our cohort included 197 pts (91.6%) with T1-3NOMO NSCLC and 18 pts (8.4%) with lung oligometastases. 10 pts had 1-3 lesions treated concurently. Female:male ratio=1.08, KPS>70%. Median tumour size was 2cm (0.5-8.5). All patients completed the prescribed SABR course. The median treatment time (including imaging) was 27 min (8-62). 29 pts (13.6%) required interruption of the fraction, optimisation of pain control and recommencement of the treatment. Median follow-up was 17.9months (0.95-83.5). At the last known follow-up, 108 pts (50%) were alive, 93 pts (43%) have died and 14pts (7%) were lost of follow-up. 5pts (2%) died suddenly within 2 months from SABR completion (non-cancer, non-treatment related deaths). Median OS was 27.8 months (22.6-33.18), with 1-, 2- and 3-years OS of 80%, 54% and 40%. LC was evaluable in 170 pts (80%) with at least 2 months follow-up post-SABR and complete imaging data. For these patients, local control rates at 1-, 2- and 3-years were 97%, 92% and 83%. There were no G4- G5 treatment related toxicities. Acute G3 toxicities were observed in 4pts(1.9%): 2 radiation pneumonitis, 2 positional related shoulder pain. Observed late toxicities were: asymptomatic rib fractures – 4pts (1.9%), mild chest wall syndrome -13 pts (6.04%), complete collapse lung/airway stenosis – 2 pts (0.93%), deterioration of the baseline dyspnea – 8 pts (3.7%). No statistically significant differences in outcomes/toxicities were observed between elderly (75-85 years old) and very elderly patients (>85 years old); however the very elderly represented only 15% of the entire cohort. Elderly and very elderly patients can successfully complete SBRT, with good local control, survival and acceptable toxicity. Elderly patients might require increased supportive care for successful treatment delivery.