Robotic Stereotactic Radiotherapy for Intracranial Meningiomas-An Opportunity for Radiation Dose De-Escalation.

OBJECTIVE: To evaluate the possibility of dose de-escalation, with consideration of the efficacy and safety of robotic stereotactic CyberKnife radiotherapy in patients diagnosed with intracranial meningiomas. METHODS: The study group consisted of 172 patients (42 men and 130 women) treated in III Radiotherapy and Chemotherapy Clinic of Maria Sklodowska-Curie National Research Institute of Oncology in Gliwice between January 2011 and July 2018. The qualification for dose de-escalation was based on MRI (magnetic resonance imaging) features: largest tumor diameter less than 5 cm, well-defined tumor margins, no edema, and no brain infiltration. The age of patients was 21-79 years (median 59 years) at diagnosis and 24-80 years (median 62 years) at radiotherapy. Sixty-seven patients (Group A) were irradiated after initial surgery. Histopathological findings were meningioma grade WHO 1 in 51 and WHO 2 in 16 cases. Group B (105 patients) had no prior surgery and the diagnosis was based on the typical features of meningioma on MRI. All patients qualified for the robotic stereotactic CyberKnife radiotherapy, and the total dose received was 18 Gy in three fractions to reference isodose 78-92%. RESULTS: Follow-up period was 18 to 124 months (median 67.5 months). Five- and eight-year progression free survival was 90.3% and 89.4%, respectively. Two patients died during the follow-up period. Progression of tumor after radiotherapy was registered in 16 cases. Four patients required surgery due to progressive disease, and three of them were progression free during further follow-up. Twelve patients received a second course of robotic radiotherapy, 11 of them had stable disease, and one patient showed further tumor growth but died of heart failure. Crude progression free survival after both primary and secondary treatment was 98.8%. Radiotherapy was well-tolerated: acute toxicity grade 1/2 (EORTC-RTOG scale) was seen in 10.5% of patients. We did not observe any late effects of radiotherapy. CONCLUSION: Stereotactic CyberKnife radiotherapy with total dose of 18 Gy delivered in three fractions showed comparable efficacy to treatment schedules with higher doses. This could support the idea of dose de-escalation in the treatment of intracranial meningiomas.

Safety and Feasibility of Radiation Therapy Combined with CDK 4/6 Inhibitors in the Management of Advanced Breast Cancer.

The addition of CDK4/6 inhibitors to endocrine therapy in advanced hormone receptor-positive HER2-negative breast cancer has led to practice-changing improvements in overall survival. However, data concerning the safety of CDK4/6i combination with radiotherapy (RT) are conflicting. A retrospective evaluation of 288 advanced breast cancer patients (pts) treated with CDK4/6i was performed, and 100 pts also received RT. Forty-six pts received 63 RT courses concurrently and fifty-four sequentially before CDK4/6i initiation (76 RT courses). Neutropenia was common (79%) and more frequent during and after concurrent RT than sequential RT (86% vs. 76%); however, CDK4/6i dose reduction rates were similar. In patients treated with CDK4/6i alone, the dose reduction rate was 42% (79 pts) versus 38% with combined therapy, and 5% discontinued treatment due to toxicity in the combined group. The risk of CDK4/6i dose reduction was correlated with neutropenia grade, RT performed within the first two CDK4/6i cycles, and more than one concurrent RT; a tendency was observed in concurrent bone irradiation. However, on multivariate regression analysis, only ECOG 1 performance status and severe neutropenia at the beginning of the second cycle were found to be associated with a higher risk of CDK4/6i dose reduction. This largest single-center experience published to date confirmed the acceptable safety profile of the CDK4/6i and RT combination without a significantly increased toxicity compared with CDK4/6i alone. However, one might delay RT for the first two CDK4/6i cycles, when myelotoxic AE are most common.

Thyroid remnant ablation with radioiodine activity of 30, 60, and 100 mCi in patients with differentiated thyroid cancer - a prospective comparison of long-term outcomes.

Introduction: The aim of this prospective study was to evaluate long-term outcomes in differentiated thyroid cancer (DTC) patients postoperatively treated with distinct RAI activities of 30 mCi, 60 mCi, and 100 mCi. Material and methods: The analysis involved 277 low-risk and 46 intermediate-risk patients, who underwent radioiodine (RAI) ablation with 30 mCi, 60 mCi or 100 mCi under prospective, randomized clinical trials. Seventy-eight patients from the low-risk group received 30 mCi, whereas 125 and 74 patients received 60 mCi and 100 mCi, respectively. Regarding the intermediate-risk group, 20 patients were given 60 mCi, and 26 subjects were given 100 mCi. The mean time of follow-up was 11 years. Results: An excellent treatment response was obtained in 88%, 89% and 90% of low-risk patients treated with 30 mCi, 60 mCi, and 100 mCi, respectively, and in 85% of intermediate-risk patients, who were administered 60 or 100 mCi. An indeterminate response was achieved in 9.4% and 6.5%, whereas an incomplete structural response was obtained in 1.4% and 6.5% of low-risk and intermediate-risk patients, respectively. An incomplete biochemical response was observed only in 2.2% of intermediate-risk patients. The differences in treatment response regarding RAI activity were not significant. Conclusions: RAI activity of 30 mCi demonstrates a comparable efficacy as 60 mCi and 100 mCi in low-risk DTC. RAI activity of 60 mCi seems to be effective in intermediate-risk DTC.