Second Chance for Cure: Stereotactic Ablative Radiotherapy in Oligometastatic Disease

Local ablative therapy, such as radiotherapy or surgery, plays a key role in treatment of patients with oligometastatic disease. Stereotactic ablative body radiotherapy (SABR) comes to the fore as a safe and effective treatment for patients with a limited number of metastases, even those located in hard-to-reach body sites. Many researchers have suggested that metastatsis-directed therapy could improve long-term progression-free survival (PFS) and overall survival (OS) in patients with oligometastases.

This was a retrospective, single-arm, observational study conducted between July 2015 and February 2022. In our institute, 60 patients with controlled primary tumors and one to five metastases were treated with SABR. Prescribed radiation doses ranged from 12 to 60 Gy administered in one to seven fractions. We aimed to determine whether metastatic-directed therapy using SABR for all oligometastases affects OS and PFS and whether the primary tumor or metastatic site influences OS/PFS.

The most common primary malignancy types were prostate (n = 14), colorectal (n = 10), lung (n = 7), and breast cancers (n = 6). The median follow-up was 30 months, ranging from 9 to 79. The 1-, 3-, and 5-year PFS and OS rates were 54.9%, 37.0%, and 37.0% and 98.3%, 84.4%, and 73.8%, respectively, and the median time to first progression was 15 (range, 2-32) months. Twenty-four (40%) patients had no recurrence. In our analysis, primary tumor site was not an independent prognostic factor. The metastatic site may influence on patient outcome in cases of localized bone and liver metastases.

In our retrospective analysis, SABR was associated with favorable levels of PFS and OS in patients with oligometastases. The limitations of our study were lacking high-level evidence, and randomized studies to compare SABR and palliative standard of care are mandatory.