Postoperative stereotactic radiosurgery improves local control of brain metastases

Stereotactic radiosurgery provided better local control than observation in patients with resected brain metastases, according to randomized study results presented at the ASTRO Annual Meeting.

However, OS and rate of distant brain metastases did not differ between groups.

Anita Mahajan

Surgical resection with subsequent whole-brain radiotherapy serves as a standard of care for patients with brain metastases; however, whole-brain radiotherapy is associated with cognitive deterioration and worsened quality of life.

Stereotactic radiosurgery uses a single fraction of precise, high-dose radiation that preserves surrounding brain tissue.

“Over the past several years, stereotactic radiosurgery has been used regularly, but it has never been tested prospectively,” Anita Mahajan, MD, professor in the department of radiation oncology at The University of Texas MD Anderson Cancer Center, said during a press conference. “Results have suggested 80% to 90% control rates when using stereotactic radiosurgery to the surgical bed.”

Some clinicians have suggested that radiotherapy may be completely forgone in certain patients.

“Our surgical colleagues feel that their techniques have improved,” Mahajan said. “When I speak to our surgeons, they say that they do a better job than ever, and there may be an option to avoid radiation completely.”

Thus, Mahajan and colleagues compared stereotactic radiosurgery with observation after complete resection in a series of 131 patients (median age, 58 years) treated at MD Anderson Cancer Center. Researchers stratified patients according to number of brain metastases (1 vs. 2-3), histology (melanoma vs. other histology) and preoperative tumor size (< 3 cm vs. > 3 cm).

The researchers assigned patients to stereotactic radiosurgery to the surgical cavity (n = 64) or observation (n = 67). Patients in the stereotactic radiosurgery arm received 12 Gy, 14 Gy or 16 Gy radiation depending on cavity volume at the time of surgery.

Patients in both arms with additional unresected brain metastases (radiosurgery, n = 34; observation, n = 28) received stereotactic radiosurgery for their unresected metastases.

Failure of local control in the surgical cavity served as the study’s primary outcome measure. Secondary outcome measures included OS, development of distant metastases, complications and the use of whole-brain radiotherapy.

Median follow-up was 12.6 months (range, 0.3-70.6).

Stereotactic radiosurgery resulted in improved local control rates at 6 months (83% vs. 57%) and 12 months (72% vs. 45%) compared with observation. Stereotactic radiosurgery was associated with superior local control overall (HR = 0.46; 95% CI, 0.25-0.85).

Median time to local recurrence was 7.6 months in the observation arm and had not been reached in the stereotactic radiosurgery arm.

Both arms had a median OS of 17 months (HR = 1.22; 95% CI, 0.79-1.87).

Further, the 12-month rates of distant brain metastases were 43% for stereotactic radiosurgery and 33% for observation (HR = 0.79; 95% CI, 0.5-1.24).

Fifty-four patients (radiosurgery, n = 24; observation, n = 30) received subsequent whole-brain radiotherapy. The median time to whole-brain radiotherapy was 16.1 months for the radiosurgery arm and 15.2 months for the observation arm (HR = 0.8; 95% CI, 0.5-1.4).

Number of lesions, histology or systemic disease status did not affect local control rates.

Better local control occurred among patients assigned stereotactic radiosurgery (HR = 0.4; 95% CI, 0.2-0.8). Larger preoperative tumors (> 3 cm) appeared associated with worse local control (HR = 2.4; 95% CI, 1.2-4.9).

“Our study noted that postoperative stereotactic radiosurgery does improve local control after a complete resection, with no difference in OS or distant brain metastases,” Mahajan said. “We are looking at groups more carefully to determine if there is a better way to identify which patients will benefit from which treatments.” – by Cameron Kelsall

Reference:

Mahajan A, et al. Abstract 3. Presented at: ASTRO Annual Meeting; Sept. 25-28; Boston.

Disclosure: Mahajan reports no relevant financial disclosures.