Marginless 5-Fraction Robotic Radiosurgery for Unfavorable Nonfunctioning Pituitary Macroadenoma: 5-year Outcomes from a Single Institution Protocol

PURPOSE/OBJECTIVE(S)

Nonfunctioning macroadenoma is a commonly diagnosed pituitary tumor. Resection is the favored treatment, with radiosurgery often utilized for residual or progressing disease. Long-term outcomes are established for single-session radiosurgery, but mature outcomes are lacking for multisession radiosurgery. We report our institution's 5-year efficacy and safety results for unfavorable nonfunctioning pituitary macroadenoma patients treated with marginless 5-fraction robotic radiosurgery.

MATERIALS/METHODS

Between 2010-2020, patients who completed marginless 5-fraction radiosurgery for the treatment of unfavorable nonfunctioning pituitary macroadenomas were included. A tumor was considered unfavorable if the gross tumor volume (GTV) was larger than 5 cc or if it closely approached a critical structure (optic apparatus, brainstem or pituitary gland). Local control was calculated using the Kaplan-Meier Method.

RESULTS

Twenty predominately female patients (60%), age from 21-77 (median: 53 years) were included in this study. All underwent primary resection. Indications for radiosurgery included unresectable recurrence (85%) and residual disease progression (70%). Median tumor volume was 3.4 cm3 (range: 0.3-20.8 cm3) and 40% of the tumors were suprasellar. A mean dose of 28.8 Gy (range: 25 Gy-30 Gy), was delivered to a median isodose line of 80% (range: 75%-89%). The median optic chiasm maximum point dose was 21.8 Gy (range: 12.0-25.9 Gy). Toxicity was minimal with 12 patients (40%) developing acute short-lived headaches and 1 patient (5%) developing a brief ipsilateral 6th nerve palsy. There was no radiation induced optic or pituitary dysfunction identified in this cohort. At a median follow up of 5 years local control was 95%. There was 1 in-field failure pathologically confirmed following surgery for pituitary tumor hemorrhage and 2 radiographically confirmed out-of-field failures in patients with large tumors (>20 cc).

CONCLUSION

The treatment of unfavorable nonfunctioning pituitary macroadenoma with marginless 5-fraction robotic radiosurgery provides excellent local control to date, with minimal toxicity. However, tumors with GTV's greater than 20 cc may require conventionally fractionated treatment with a margin to optimize local control.

Hypofractionated Intensity Modulated Proton Therapy (IMPT) and Systemic Therapy for Unresectable Hepatobiliary Cancers

PURPOSE/OBJECTIVE(S)

Proton therapy offers significantly reduced normal liver dose compared to photon therapy for liver tumors, and therefore has the potential for dose escalation and hypofractionation. Employing IMPT, we have initiated a hypofractionated treatment regimen for unresectable liver cancer at a single academic institution. Here we report our initial results on dosimetry and clinical outcomes of hypofractionated IMPT for unresectable hepatocellular carcinoma (HCC) and cholangiocarcomas (CC).

MATERIALS/METHODS

We retrospectively reviewed records of consecutive patients treated with IMPT for CC and HCC from 2018 to 2021. Inverse treatment planning with robust optimization, daily image guidance, pencil beam scanning dose delivery were used for all patients. Motion management included 4D-CT and abdominal compression. Toxicity was graded using the Common Terminology Criteria for Adverse Events version 5.0 and survival was calculated using the Kaplan Meier method.

RESULTS

We identified 15 patients (3 HCC, 4 intrahepatic CC, 8 hilar CC) treated with IMPT to a median dose of 5805 cGy (range, 4500 - 6000 cGy) in 15 fractions. Two had metastatic and 13 had regional disease. Median tumor volume was 91.5 cc (range, 10.92 - 366.31 cc). Prior therapies included: 12 patients received upfront chemotherapy, (gemcitabine plus cisplatin most common), 4 received prior surgery on the liver, and 5 received prior liver directed treatment. With a median follow up of 10 months, the median overall survival (OS) and 1-year OS was 18.7 months and 76% respectively. One patient underwent resection and 1 patient received liver transplant; 7 (47%) patients had disease progression (3 local, 1 regional lymph node, 4 elsewhere liver, 5 distant metastatic). Five patients with CC developed grade 3 toxicity in the form of cholangitis (4) and hemobilia (1). Of these patients, 4 patients were of the hilar type.

CONCLUSION

Our early results using hypofractionated IMPT for unresectable HCC and CC resulted in encouraging local control rates with an acceptable toxicity profile. Further study is warranted to determine the optimal liver directed therapy for this challenging patient population.