Adult Brain Tumors Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Treatment Option Overview
A randomized trial tested radiosurgery as a boost added to standard EBRT, but the trial found no improvement in survival, quality of life, or patterns of relapse compared to EBRT without the boost. Based upon a similar rationale, the use of single-fraction stereotactic radiosurgery has disseminated into common practice. High doses of radiation are delivered to the tumor bed with a small margin of nonclinically involved brain. Again, there are no randomized trials that test this concept in comparison to standard radiation.
For the same theoretical reasons, brachytherapy has been used to deliver high doses of radiation locally to the tumor while sparing normal brain tissue. However, this approach is technically demanding and has fallen out of favor with the advent of the above-mentioned techniques.
The role of immediate PORT for low-grade gliomas (i.e., low-grade astrocytoma, oligodendroglioma, mixed oligoastrocytomas) is not as clear as in the case of high-grade tumors. The European Organisation for Research and Treatment of Cancer (EORTC) randomly assigned 311 patients with low-grade gliomas to radiation versus observation in the EORTC-22845 and MRC BR04 trial.[15,16] (On central pathology review, about 25% of the patients on the trial were felt to actually have high-grade tumors.) Most of the control patients received radiation at the time of progression. After a median follow-up of 93 months, median progression-free survival was 5.3 years in the radiation arm versus 3.4 years in the control arm (HR = 0.59; 95% CI, 0.45–0.77).[15,16][Level of evidence: 1iiDiii] However, there was no difference in the OS rate (median survival = 7.4 years vs. 7.2 years; HR = 0.97; 95% CI, 0.71–1.34; P = .87).[15,16][Level of evidence: 1iiA] This was caused by a longer survival after progression in the control arm (3.4 years) than in the radiation arm (1.0 years) (P < .0001). The investigators did not collect reliable quality-of-life measurements, so it is not clear whether the delay in initial relapse in the radiation therapy arm translated into improved function or quality of life.
Repeat radiation therapy (re-irradiation)
Because there are no randomized trials, the role of repeat radiation after disease progression or the development of radiation-induced cancers is also ill defined. The literature is limited to small retrospective case series, which makes interpretation difficult. The decision to use repeat radiation must be made carefully because of the risk of neurocognitive deficits and radiation-induced necrosis. One advantage of radiosurgery is the ability to deliver therapeutic doses to recurrences that may require the reirradiation of previously irradiated brain tissue beyond tolerable dose limits.
For many years, the nitrosourea carmustine (BCNU) was the standard chemotherapy added to surgery and radiation for malignant gliomas. This was based upon a randomized trial (RTOG-8302) of 467 patients conducted by the Brain Tumor Study Group that compared four regimens after initial resection:
- Semustine (methyl-CCNU).
- Radiation therapy.
- Radiation therapy plus carmustine.
- Radiation therapy plus semustine.