Patients with oligometastatic cancer who had two or fewer known risk factors demonstrated superior OS after stereotactic radiotherapy than patients with three or more risk factors, according to study results.
“These patients are candidates for inclusion in prospective randomized trials for defining the role of stereotactic radiotherapy in the management of oligometastases,” the researchers wrote.
It is unclear which subset of patients with inoperable oligometastases derive a survival benefit from stereotactic radiotherapy. For this reason, researchers assessed OS in 309 patients with five or more metastases treated with stereotactic body radiotherapy (n=209) or intracranial single or fractionated stereotactic radiotherapy (n=107).
Median OS was 2 years. OS rates were 32% at 3 years, 25% at 4 years and 19% at 5 years.
Factors associated with poorer survival were nonadenocarcinoma histology (P<.01), intracranial metastases (P<.01), synchronous oligometastatic disease (P<.01) and male sex (P=.02).
Median survival was 40 months (95% CI, 24-63) among patients with none of the above risk factors, 29 months (95% CI, 23-35) among those with one risk factor, and 23 months (95% CI, 16-29) among those with two risk factors. Median survival was 9 months among patients with three risk factors (95% CI, 6-11) and 4 months among patients with four risk factors (95% CI, 1-7).
Disclosure: See the study for a full list of the researchers’ relevant financial disclosures.