Intensity-Modulated Radiosurgery for Patients with Brain Metastases: A Mature Outcomes Analysis

Quality assurance analysis of hippocampal avoidance in a melanoma whole brain radiotherapy randomized trial shows good compliance

BACKGROUND

Melanoma brain metastases (MBM) often cause morbidity and mortality for stage IV melanoma patients. An ongoing randomised phase III trial (NCT01503827 - WBRT-Mel) evaluates the role of adjuvant whole brain radiotherapy (WBRT) following local treatment of MBM. Hippocampal avoidance during WBRT (HA-WBRT) has shown memory and neurocognitive function (NCF) preservation in the RTOG-0933 phase II study. This study assessed the quality assurance of HA-WBRT within the WBRT-Mel trial according to RTOG-0933 study criteria.

METHODS

Hippocampal avoidance was allowed in approved centres with intensity-modulated radiotherapy capability. Patients treated by HA-WBRT were not randomized within the WBRT arm. The RTOG 0933 contouring Atlas was used to contour hippocampi. In the trial co-ordinating centre, patients were treated with volumetric modulated arc therapy using complementary arcs; similar techniques were used at other sites. Dosimetric data were extracted retrospectively and analysed in accordance with RTOG 0933 study constraints criteria.

RESULTS

Among the 215 patients accrued to the WBRT-Mel study between April 2009 and September 2017, 107 were randomized to the WBRT arm, 22 were treated by HA-WBRT in 4 centers. Eighteen patients were treated in the same centre. The median age was 65 years. The commonest (91%) HA-WBRT schema was 30 Gy in 10 fractions. Prior to HA-WBRT, 10 patients had been treated by surgery alone, six by radiosurgery alone, four by surgery and radiosurgery and two exclusively by simultaneous integrated boost concurrent to HA-WBRT. Twenty patients were treated with intention to spare both hippocampi and two patients had MBM close to one hippocampus and were treated with intention to spare the contralateral hippocampus. According to RTOG-0933 study criteria, 18 patients (82%) were treated within constraints and four patients (18%) had unacceptable deviation in just one hippocampus.

CONCLUSIONS

This dosimetric quality assurance study shows good compliance (82%) according to RTOG-0933 study dosimetric constraints. Indeed, all patients respected RTOG hippocampal avoidance constraints on at least one hippocampus. In the futureanalysis of the WBRT-Mel trial, the NCF of patients on the observation arm, WBRT arm and with HA-WBRT arm will be compared.

On the cutting edge of intensity modulated radiotherapy and simultaneous integrated boost (IMRT-SIB): The case of a patient with 8 brain metastases

BACKGROUND

Patients with multiple brain metastases, especially those with more than 3 lesions, usually undergo to palliative whole brain (WB) radiotherapy (RT).

METHODS

A breast cancer patient with 8 brain metastases was treated on the brain by a radical RT regimen. Prescription doses were according to the simultaneous integrated boost-intensity modulated radiation therapy (SIB-IMRT) technique with all lesions as well brain irradiated simultaneously in 20 daily fractions. Doses of 40.0 Gy (2.0 Gy/fraction) and 50.0 Gy (2.5 Gy/fraction) were prescribed to the whole brain and to eight individual metastases, respectively.

RESULTS

Mean volume of the eight metastases was 8.1 cc (range: 3.8-10.1 cc). For all lesions, the volume receiving 95% of prescribed dose was 100% and dose homogeneity was within 3%. Moreover, maximum doses were less than 105% of prescribed dose, while average mean dose to lesions was 50.6 Gy (range: 49.7-51.5 Gy). Whole brain mean dose was 45.2 Gy. Maximum doses to brainstem and optic chiasma were limited to 44.5 Gy and 42.9 Gy, respectively, while maximum doses to eyes, lens and optic nerves were limited to 9.2 Gy, 4.9 Gy and 41.0 Gy, respectively. From a clinical point of view, subsequent MRI brain controls showed a complete clinical response. Forty months after treatment the patient is disease free and shows no late brain and skin toxicities.

CONCLUSION

This case demonstrates the technical feasibility of a SIB-IMRT treatment in patients with more than 3 brain metastases.

Single-isocenter frameless intensity-modulated stereotactic radiosurgery for simultaneous treatment of multiple brain metastases: clinical experience

PURPOSE

To describe our clinical experience using a unique single-isocenter technique for frameless intensity-modulated stereotactic radiosurgery (IM-SRS) to treat multiple brain metastases.

METHODS AND MATERIALS

Twenty-six patients with a median of 5 metastases (range, 2-13) underwent optically guided frameless IM-SRS using a single, centrally located isocenter. Median prescription dose was 18 Gy (range, 14-25). Follow-up magnetic resonance imaging (MRI) and clinical examination occurred every 2-4 months.

RESULTS

Median follow-up for all patients was 3.3 months (range, 0.2-21.3), with 20 of 26 patients (77%) followed up until their death. For the remaining 6 patients alive at the time of analysis, median follow-up was 14.6 months (range, 9.3-18.0). Total treatment time ranged from 9.0 to 38.9 minutes (median, 21.0). Actuarial 6- and 12-month overall survivals were 50% (95% confidence interval [C.I.], 31-70%) and 38% (95% C.I., 19-56%), respectively. Actuarial 6- and 12-month local control (LC) rates were 97% (95% C.I., 93-100%) and 83% (95% C.I., 71-96%), respectively. Tumors <or=1.5 cm had a better 6-month LC than those >1.5 cm (98% vs. 90%, p = 0.008). New intracranial metastatic disease occurring outside of the treatment volume was observed in 7 patients. Grade >or=3 toxicity occurred in 2 patients (8%).

CONCLUSION

Frameless IM-SRS using a single-isocenter approach for treating multiple intracranial metastases can produce clinical outcomes that compare favorably with those of conventional SRS in a much shorter treatment time (<40 minutes). Given its faster treatment time, this technique is appealing to both patients and personnel in busy clinics.