Central Nervous System

PD 03 - CNS 1 - Poster Discussion - Toxicity and Quality of Life

1019 - Whole Brain Re-irradiation Using Pulsed Reduced Dose Rate

Sunday, October 21
4:51 PM - 4:57 PM
Location: Room 217 A/B

Whole Brain Re-irradiation Using Pulsed Reduced Dose Rate
A. Burr1, D. M. Francis2, I. Robins2, and S. P. Howard2; 1Department of Human Oncology, University of Wisconsin, Madison, WI, 2Department of Human Oncology, University of Wisconsin Hospital and Clinics, Madison, WI

Purpose/Objective(s): Recurrent intracranial metastases poses a significant therapeutic challenge. While intracranial metastases are being addressed more frequently with stereotactic radiosurgery, there are still situations where whole brain radiation and whole brain re-irradiation remain beneficial, such as in patients with large numbers or large size of brain metastases. Whole brain re-irradiation has been previously limited by the significant toxicity incurred. Pulsed reduced dose rate radiation may address this by slowing the dose rate thereby allowing for real-time repair of sublethal damage. Here, we report our experience utilizing pulsed reduced dose rate radiation therapy (PRDR), as a method to limit toxicity in patients who required re-irradiation.

Materials/Methods: Patients treated from January 2001 to January 2017 with whole brain PRDR were analyzed. The median total whole brain dose was 60 Gy. The median re-irradiation dose was 26 Gy, delivered in 2 Gy fractions, at an apparent dose rate of 6.67 cGy/minute. KPS, RPA, age, number of brain metastases, size of largest brain metastases, dexamethasone dose, and time from initial radiation dose were all analyzed for correlation with overall survival using Cox regression analysis. Overall survival was estimated using the Kaplan Meier method.

Results: Sixty-three patients were treated with whole brain PRDR. The median age was 53 (range 26-72), the median KPS was 80, and 90% had an RPA of 2. 23 patients (37%) had more than 10 metastases with a median number of 5, while 8 patients (13%) had leptomeningeal disease. The median overall survival for all patients treated was 4.1 months (95% CI: 2.95-5.26 months). Five patients survived more than one year, and the longest surviving patient lived 58 months. Patients with breast cancer (20 patients) and small cell lung cancer (11 patients) had median survivals of 3.6 and 4.5 months, respectively, while NSCLC patients (13 patients) had a survival of 2.9 months. Univariate analysis showed kps of <=70 and age of >= 60 or greater were statistically associated with worse outcomes. Having greater than 10 brain metastases, metastases larger than 2 cm, or leptomeningeal disease were not associated with worse survival. Treatments were generally well tolerated with one tonic clonic seizure, one patient with worsening weakness, and 5 patients stopping treatment to go to hospice. Dexamethasone dose was decreased in 8, increased in 6, and remained the same in 17 patients for whom records of dose were available.

Conclusion: This study analyzes a cohort of patients with generally very advanced intracranial disease, who underwent palliative re-irradiation with PRDR. The median survival was very similar to what would be expected for a patient with a RPA of 2 at the time of initial diagnosis. The treatments were well tolerated with small proportion achieving long term survival. The next step for this work will be prospective evaluation of toxicity and survival.

Author Disclosure: A. Burr: None. D.M. Francis: None. I. Robins: None. S.P. Howard: None.

Adam Burr, MD, PhD

Disclosure:
Employment
University of Wisconsin Hospitals and Clinics: Resident: Employee; UW Health: Resident: Employee

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