Survival and Prognostic Factors of 40 Patients with Pulmonary Oligometastases Treated with Tomotherapy Hypofractionated Radiotherapy

Abstract

Background: With continued improvement in radiotherapy technology, hypofractionated radiotherapy has helped achieve good results in the local control and toxicity of pulmonary oligometastases. This study aimed to investigate the efficacy of radiotherapy and the prognostic factors that affect survival in patients with pulmonary oligometastases who undergo helical tomotherapy (TOMO) hypofractionated radiotherapy.Methods: Ninety pulmonary oligometastases in 40 patients (26 males, 14 females; median age 57 years) were retrospectively investigated and treated with hypofractionated radiotherapy in the Department of Oncology and Radiotherapy of the First Affiliated Hospital of Bengbu Medical College during 2018-2020. Their Karnofsky performance status (KPS) was ≥70 points. The primary endpoints were overall survival (OS), local control (LC), and progression-free survival (PFS), and we determine the related influencing factors.Results: The median gross tumor volume (GTV) and planning target volume (PTV) were 9.7 cm³ (range 1.1–287.0 cm³) and 56.9 cm³ (range 16.3–494.2 cm³), respectively, the median biological effective dose, α/β=10 (BED10), was 76.8 Gy (range 56-96 Gy), and four-dimensional computed tomography positioning was applied to 52.5% of the patients. All patients completed the treatment plan during a median follow-up of 16.1 months (range 4.9–33.3 months). The 1- and 2-year OS rates were 90.3% and 55.2%, respectively. The 1- and 2-year LC rates were 80.8% and 64.7%, respectively. The 1- and 2-year PFS rates were 47.3% and 28.4%, respectively. Univariate analysis revealed that colorectal primary (p=0.004), age >57 years (p=0.037), and number of organ metastases ≥2 (p=0.046) were associated with OS, whereas disease-free interval (DFI) ≤17.4 months (p=0.032), number of lung metastases≥2 (p=0.049), and PTV >56.9 cm³ (p=0.041) were associated with LC; and number of metastatic organs ≥2 (p=0.015) was independently associated with PFS. In multivariate analysis, colorectal cancer (p=0.010) and age >57 years (p=0.009) were significantly associated with OS. No > grade 3 toxic reaction.Conclusions: The median OS, LC, and PFS rates of TOMO hypofractionated radiotherapy for pulmonary oligometastases were 24.9, 25.9, and 11.8 months, respectively, showing that good survival rates and low toxicity could still be achieved using the medium dose.