Feasibility and safety of 1.5 T MR-guided and daily adapted abdominal-pelvic SBRT for elderly cancer patients: geriatric assessment tools and preliminary patient-reported outcomes.

Background: We present preliminary data of the first older cancer patients treated with Hybrid Linac for stereotactic body radiotherapy (SBRT) consisting of 1.5 T MRI-guided and daily-adapted treatment. The aim was to assess feasibility, safety and the role of G8 and Charlson Comorbidity Index (CCI) questionnaires in predicting patients' QoL, evaluated by patient-reported outcome measures (PROMs).

Methods: Two groups of patients with localized prostate cancer or abdominal-pelvic oligometastases were analyzed. SBRT schedule consisted of 35 Gy delivered in 5 fractions. The primary endpoint was to measure the impact of G8 and CCI on PROMs. Both G8 and the CCI were performed at baseline, while the EORTC Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) for PROMs assessment was prospectively performed at baseline and after SBRT.

Results: Forty older patients were analyzed. The median age was 73 years (range 65-85). For the entire population, the median G8 score was 15 (10-17) and the median CCI score was 6 (4-11). Concerning the PROMS, the EORTC-QLQ C30 questionnaire reported no difference between the pre- and post-SBRT evaluation in all patients, except for the fatigue item that declined after SBRT, especially in the group of patients with a G8 score < 15 and with age < 75 years (p = 0.049). No grade 3 or higher acute toxicity occurred.

Conclusion: This is the first report documenting for older cancer patients that 1.5 T MRI-guided daily-adapted SBRT is feasible, safe and does not impact on the QoL at the end of treatment. Longer follow-up is advocated to report long-term outcomes.

Trial Registration: Date of approval April 2019 and numbered MRI/LINAC no. 23748.