Central Nervous System Metastases by Unknown

Author:Unknown
Language: eng
Format: epub
ISBN: 9783030234171
Publisher: Springer International Publishing

Although previous randomized studies had established WBRT preceded by surgical resection as standard of care in the early 1990s [44], for the case of a single BM due to improvement in prognosis, the contemporary introduction of SRS for the treatment of BM [2] provided the hopes of a less invasive intervention compared to surgery with similar outcome, especially for lesions in eloquent cortex or deep-seated tumors usually thought to be unresectable.

In the RTOG 9508, Andrews et al. [51] provided the first multi-institutional prospective randomized comparison of WBRT with vs. without SRS boost where patients had one to three newly diagnosed BM and KPS ≥70 at the time of randomization and could have undergone prior BM resection. BM were deemed unresectable if they were located in deep gray matter or in eloquent cortex. Inclusion criteria permitted the largest remaining lesion maximum diameter ≤4 cm with additional tumors ≤3 cm. Patients with lesions in the brainstem or <1 cm from the optics were excluded. Patients were randomized to WBRT with vs. without SRS boost within 1 week of completing WBRT, using SRS doses by size group per RTOG 9005. In this study, 63% of the cancer primaries were from lung origin. WBRT was given with a dose of 37.5 Gy in 2.5 Gy fractions in both arms. Despite a 19% failure to receive SRS, there was a significant survival benefit by univariate analysis in patients with a single unresectable BM allocated to the SRS group, with median survival time of 6.5 vs. 4.9 months in the WBRT alone group, with a predominance in RPA class II patients. In patients with multiple BM, however, researchers detected no significant difference in survival with SRS boost treatment vs. WBRT alone (5.7 vs. 6.5 months), unless patients belonged to RPA class I or had a favorable histologic status (squamous cell or NSCLC) by multivariate analysis. Statistically significant stability or improvement in KPS and decreased steroid use at 6 months was noted in all patients who had SRS boost treatment vs. those who did not. At 12 months, SRS boost vs. WBRT alone provided significant improvement in local intracranial control (defined as unchanged or improved on serial post-treatment MRI scans) with 82% vs. 71%, with no difference in overall intracranial control, as expected due to the local effect of SRS. No difference in rates of neurological death was noted between groups, and similar rates of early and late CNS toxicity were seen. RTOG 9508 provided a recommendation for SRS boost after WBRT as standard of care for single BM and suggested a consideration of SRS for two to three BM based on improved performance in all patients.

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