A Systematic Comparison of Dose Distributions Delivered in 125I Plaque Brachytherapy and Proton Radiation Therapy for Ocular Melanoma.

PURPOSE: To characterize dose distributions with 125I plaque brachytherapy compared with proton radiation therapy for ocular melanoma for relevant clinical scenarios, based on tumor base diameter (d), apical height (h), and location. METHODS AND MATERIALS: Plaque and proton treatment plans were created for 4 groups of cases: (1) REF: 39 instances of reference midsize circular-base tumor (d = 12 mm, h = 5 mm), in locations varying by retinal clock hours and distance to fovea, optic disc, and corneal limbus; (2) SUP: 25 superiorly located; (3) TEMP: 25 temporal; and (4) NAS: 25 nasally located tumors that were a fixed distance from the fovea but varying in d (6-18 mm) and h (3-11 mm). For both modalities, 111 unique scenarios were characterized in terms of the distance to points of interest, doses delivered to fovea, optic disc, optic nerve at 3 mm posterior to the disc (ON@3mm), lens, and retina. Comparative statistical evaluation was performed with the Mann-Whitney U test. RESULTS: Superior dose distributions favored plaque for sparing of (1) fovea in large (d + h ≥ 21 mm) NAS tumors; (2) ON@3mm in REF cases located ≤4 disc diameters from disc, and in NAS overall. Protons achieved superior dose sparing of (1) fovea and optic disc in REF, SUP, and TEMP; (2) ON@3mm in REF >4 disc diameters from disc, and in SUP and TEMP; and (3) the lens center overall and lens periphery in REF ≤6 mm from the corneal limbus, and in TEMP with h = 3 mm. Although protons could completely spare sections of the retina, plaque dose was more target conformal in the high-dose range (50% and 90% of prescription dose). CONCLUSIONS: Although comparison between plaque and proton therapy is not straightforward because of the disparity in dose rate, prescriptions, applicators, and delivery techniques, it is possible to identify distinctions between dose distributions, which could help inform decisions by providers and patients.

Intraoperative Radiotherapy in the Era of Intensive Neoadjuvant Chemotherapy and Chemoradiotherapy for Pancreatic Adenocarcinoma.

OBJECTIVES: Improved outcomes with FOLFIRINOX or gemcitabine with nab-paclitaxel in the treatment of metastatic pancreatic adenocarcinoma (PDAC) have prompted incorporation of these regimens into neoadjuvant treatment of locally advanced unresectable PDAC. Whereas some patients remain unresectable on surgical exploration, others are able to undergo resection after intensive neoadjuvant treatment. We evaluated outcomes and toxicity associated with use of intensive neoadjuvant treatment followed by intraoperative radiotherapy (IORT) in combination with resection or exploratory laparotomy. METHODS: We retrospectively analyzed patients with locally advanced unresectable or borderline-resectable PDAC who received intensive neoadjuvant treatment with induction chemotherapy and chemoradiotherapy followed by exploratory laparotomy in an IORT-equipped operating suite between 2010 and 2015. Surgical outcomes and overall survival (OS) were compared. RESULTS: Of 68 patients, 41 (60.3%) underwent resection, 18 (26.5%) had unresectable disease, and 9 (13.2%) had distant metastases. Of 41 resectable patients, 22 received IORT for close/positive resection margins on intraoperative frozen section. There was no significant difference in operative times or morbidity with addition of IORT to resection. Median OS was 26.6 months for all patients who underwent resection, 35.1 months for patients who underwent resection and IORT, and 24.5 months for patients who underwent resection alone (P=NS). Of 18 patients with unresectable disease, all but 1 received IORT, with median OS of 24.8 months. IORT was associated with increased hospital stay (4 vs. 3.5 d), but no significant difference in operative times or morbidity. CONCLUSIONS: IORT in addition to intensive neoadjuvant chemotherapy and chemoradiotherapy was not associated with increased toxicity when used with resection or exploratory laparotomy, and was associated with encouraging survival rates in patients with close/positive margins and patients with unresectable disease.