RADT-06. RADIOTHERAPY FOR BRAIN METASTASES FROM THYROID CANCER: A RETROSPECTIVE COHORT STUDY

PURPOSE/OBJECTIVE(S) Brain metastases from thyroid carcinoma are rare. Although stereotactic radiosurgery (SRS) is a standard of care for patients with brain metastases across many histologies, the current NCCN guidelines do not support a universal role for this modality in thyroid cancer. MATERIALS AND METHODS Thyroid cancer patients with brain metastases treated with radiotherapy at our institution from 2002-2020 were studied. Cumulative risk of local failure, distant intracranial failure and radiation necrosis were calculated using a competing risk of death analysis and censored at the last imaging follow-up. Overall survival was analyzed using Kaplan-Meier method. Stratified cox regression was used to study per-lesion outcomes. RESULTS We identified 34 patients with 203 treated brain metastases. 179 (88.2%) lesions were of differentiated histology; the remainder were anaplastic histology. Four patients received whole brain radiotherapy (WBRT) while 30 patients received SRS (SFED 22, interquartile (IQ) range 20-22). Of the patients receiving WBRT, one (25%) had anaplastic histology, and the median number of lesions was 15 (as compared to 2 for SRS). Median follow up among survivors was 32.3 months and median survival was 10.8 months. There were no observed failures (local or distant intracranial) observed at 1 year in the 24 metastases with anaplastic histology, although competing risk of death was high (91.7%). The 1 year cumulative incidences of local failure and distant intracranial failures were 9.8% (95CI 5.7%-13.9%) and 35.0% (95CI 29.0%-41.0%), respectively, in differentiated tumors. 6 (10.2%) of the distant intracranial failures were new cases of leptomeningeal disease. The 1 year risk of radiation necrosis was 15.5%. Of these cases, most were Grade 2 (57.1%); 3 (42.9%) were Grade 4 (there were no Grade 1 or 3 events). CONCLUSION In the largest known cohort of thyroid cancer brain metastasis patients, radiotherapy and SRS appear to be safe and effective treatment modalities.

Diagnosis and Predictors of Treatment Outcomes in Meningiomas with Atypical or Anaplastic Histology

Atypical and anaplastic meningiomas (WHO grade II and III) are uncommon tumors with poorer prognosis than benign meningiomas. They represent a small and heterogeneous subgroup of meningiomas that has more aggressive biological nature and higher frequency of recurrence. Treatment of these tumors remains challenging and recurrence is common even after gross total resection. We report five year experience of an experienced neurosurgical center (INC) reviewing treatment options and predictor of treatment outcomes for malignant meningiomas.

Predictors of Treatment Response and Survival Outcomes in Meningioma Recurrence with Atypical or Anaplastic Histology

BACKGROUND Recurrence rates for atypical and anaplastic meningiomas range between 9% and 50% after gross total resection and between 36% and 83% after subtotal resection. Optimal treatment of recurrent meningiomas exhibiting atypical/anaplastic histology is complicated because they are often refractory to both surgery and radiation. OBJECTIVE To evaluate clinical determinants of recurrence and treatment-specific outcomes in patients with recurrent meningiomas exhibiting atypical/anaplastic histology at our institution. METHODS A cohort study was conducted using clinical data of all patients treated for meningiomas with atypical/anaplastic histology at first recurrence between January 1985 and July 2014 at a tertiary cancer center. Predictors of second recurrence were analyzed using competing risks regression models. RESULTS Nine hundred eighteen patients with meningioma were screened, of whom 60 (55% female) had recurrent disease with atypical/anaplastic histology at a median age of 58.1 yr at diagnosis. The median follow-up from the time of first recurrence was 36.7 mo, with 32 (53%) patients alive at last follow-up. There was no effect of extent of resection at first recurrence on time to a subsequent recurrence. Inclusion of radiation as primary or adjuvant therapy at first recurrence reduced the risk of progression or subsequent recurrence compared to surgery alone (P = .07). CONCLUSION Treatment of recurrent meningiomas with atypical/anaplastic histology remains challenging. Our data, from one of the largest cohorts, suggest better tumor control with the addition of radiation and challenges the importance of extent of resection at first recurrence. A multicenter effort is needed to confirm these findings and propose treatment guidelines.

Treatment of Anaplastic Histology Wilms' Tumor: Results From the Fifth National Wilms' Tumor Study

Purpose An objective of the fifth National Wilms' Tumor Study (NWTS-5) was to evaluate the efficacy of treatment regimens for anaplastic histology Wilms' tumor (AH). Patients and Methods Prospective single-arm studies were conducted. Patients with stage I AH were treated with vincristine and dactinomycin for 18 weeks. Patients with stages II to IV diffuse AH were treated with vincristine, doxorubicin, cyclophosphamide, and etoposide for 24 weeks plus flank/abdominal radiation. Results A total of 2,596 patients with Wilms' tumor were enrolled onto NWTS-5, of whom 281 (10.8%) had AH. Four-year event-free survival (EFS) and overall survival (OS) estimates for assessable patients with stage I AH (n = 29) were 69.5% (95% CI, 46.9 to 84.0) and 82.6% (95% CI, 63.1 to 92.4). In comparison, 4-year EFS and OS estimates for patients with stage I favorable histology (FH; n = 473) were 92.4% (95% CI, 89.5 to 94.5) and 98.3% (95% CI, 96.4 to 99.2). Four-year EFS estimates for patients who underwent immediate nephrectomy with stages II (n = 23), III (n = 43), and IV (n = 15) diffuse AH were 82.6% (95% CI, 60.1 to 93.1), 64.7% (95% CI, 48.3 to 77.7), and 33.3% (95% CI, 12.2 to 56.4), respectively. OS was similar to EFS for these groups. There were no local recurrences among patients with stage II AH. Four-year EFS and OS estimates for patients with bilateral AH (n = 29) were 43.8% (95% CI, 24.2 to 61.8) and 55.2% (95% CI, 34.8 to 71.7), respectively. Conclusion The prognosis for patients with stage I AH is worse than that for patients with stage I FH. Novel treatment strategies are needed to improve outcomes for patients with AH, especially those with stage III to V disease.