Stereotactic Ablative Radiotherapy Feasible for Recurrent Oligometastatic Cancer

Stereotactic ablative radiation therapy (SABR) was shown to be a practical and tolerable therapy option for patients with recurrent oligometastatic cancer that did not adversely affect patient-reported quality of life (QoL), according to results from a recent phase 2 multi-center study (Int J Radiat Oncol Biol Phys. 2019;103[1]:116-122).

“Oligometastatic disease has emerged as a potentially curable state in the spectrum of cancer progression. Aggressive local therapy such as…SABR…may improve oncologic outcomes,” explained Philip Sutera, BS, Department of Radiation Oncology, UPMC Hillman Cancer Center, University of Pittsburgh School of Medicine, Pennsylvania, and colleagues, who conducted a study to test SABR in this setting.

Dr Sutera and colleagues prospectively recruited 147 patients with oligometastatic cancer (median age, 66.4 years) to the study between 2011 and 2017. SABR dose and fractionation were based on lesion size and location, and patient follow-up occurred within 6 weeks of SABR completion and at 3-month intervals.

At baseline and each follow-up thereafter, patients were given a Functional Assessment of Cancer Therapy-General questionnaire to evaluate patient-reported QoL. Dr Sutera and colleagues used a reverse Kaplan-Meier method to calculate median follow-up and the Kaplan-Meier method to measure overall survival (OS), progression-free survival (PFS), and distant PFS.

Lung (21.8%), colorectal (21.1%), and head and neck (10.9%) cancers were the most common primary tumors among study participants. At a median follow-up of 41.3 months, the median OS

was 42.3 months (95% confidence interval, 27.4-∞), with a 5-year OS of 43%. The 5-year

local PFS was 74%, and the distant PFS was 17%.

Acute toxicity of grade 2+ and 3+ was 7.5% and 2.0%, respectively; late grade 2+ and 3+ toxicity was 1.4% for both grades. Of note, the investigators did not observe any significant changes in QoL at completion and at 6 weeks, 3 months, and 9 months posttreatment. A statistically significant improvement in patient-reported QoL was observed at 6 months and 12 months.

“Our results demonstrate SABR to be a safe and effective treatment modality that demonstrates excellent overall survival and local control,” Dr Sutera and colleagues said.

“Additionally, we report very low rates of acute and late grade 3 toxicity and show SABR to have no significant adverse effect on patient-reported quality of life,” they concluded.—Hina Khaliq