B.S. Teh

Salvage intensity modulated radiotherapy using endorectal balloon after radical prostatectomy

To evaluate biochemical non‐evidence of disease and adverse events of salvage intensity‐modulated radiotherapy using an endorectal balloon for prostate cancer patients after radical prostatectomy.

Pelvic radiotherapy does not increase the complication rates of artificial urinary sphincter implantation

Aims of Study Patients with pelvic radiotherapy (XRT) have impaired tissue healing capacity, small vessel occlusion and ischemia, and more complex etiology of incontinence secondary to detrusor hyperactivity and decreased compliance. It is unclear whether XRT increases the complication rates of artificial urinary sphincter (AUS) implantation for intrinsic sphincter deficiency (ISD) because of these adverse factors. Two recent publications revealed conflicting results (1, 2). We present the largest contemporary retrospective series to date to clarify the issue.

Complete Local and Abscopal Responses from a Combination of Radiation and Nivolumab in Refractory Hodgkin's Lymphoma

Until recently, patients with relapsed Hodgkins lymphoma after brentuximab vedotin (Bv) treatments had poor treatment outcomes. Checkpoint inhibitors such as nivolumab and pembrolizumab that bind to and inhibit programmed cell death protein-1 (PD-1), have demonstrated an overall response rate of 70% in Hodgkins lymphoma patients; however, complete response is still low at 20% with median progression-free survival of 14 months. There are ongoing clinical studies to seek out synergistic combinations, with the goal of improving the complete response rates for the cure of Hodgkins lymphoma. Although radiotherapy has a limited survival benefit in such refractory patients, several preclinical models and anecdotal clinical evidence have suggested that combining local tumor irradiation with checkpoint inhibitors can produce systemic regression of distant tumors, an abscopal effect. Most of these reported studies on the response with local conformal radiotherapy and checkpoint inhibitors in combination with the anti-cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) antibody-ipilimumab are in melanoma. Here we report in our case series that the checkpoint inhibitors that block CTLA4 and B7-homolog 1 (B7-H1) or PD-1 in preclinical radiotherapy models have shown an increased the rate of tumor regression. Our case series demonstrates that combining local irradiation with anti-PD-1 checkpoint blockade treatment is feasible and synergistic in refractory Hodgkins lymphoma. Correlative studies also suggest that the expression of programmed death-ligand 1 (PD-L1), DNA damage response and mutational tumor burden can be used as potential biomarkers for treatment response.

2192 : The Treatment of Primary and Metastatic Renal Cell Carcinoma (RCC) With Stereotactic Body Radiation Therapy (SBRT) and Stereotactic Radiosurgery (SRS)

14572 Background: RCC is often regarded as a radio-resistant tumor. However, brain metastases from RCC have been successful treated with SRS. Therefore, metastases to extra-cranial sites may be treated with similar success using stereotactic body radiation therapy (SBRT), where image-guidance allows for the delivery of precise high dose radiation in a few fractions. We report our experience with SRS/SBRT in the management of primary and metastatic RCC.nnnMETHODSnThe image-guided Novalis radiation therapy system was used. Thirty patients with brain metastases were treated with SRS (16-22 Gy in a single fraction). Five of these patients underwent resection of their metastatic lesions after SRS and their pathology were reviewed. Twenty patients with extra-cranial metastatic lesions (orbits, head and neck, lung, mediatinum, sternum, clavicle, scapula, humerus, rib, spine, abdomen) and 2 patients with biopsy proven primary RCC (not surgical candidates), were treated with SBRT (24-32 Gy in 3-4 fractions over 1-2 weeks). All patients were immobilized in body cast and image-guidance was used for all fractions. 4D-CT was utilized in the treatment planning to assess tumor motion.nnnRESULTSnOf the 30 patients who received SRS to brain metastases, 25 showed decreasing or stable lesion size. Five patients showed an increase in size and underwent resection. Their pathology revealed necrosis in >99% of the specimen, with no viable RCC. Nineteen patients who received SBRT to extra-cranial metastases achieved symptom relief. One patient had local progression, yielding a local control rate of 95%. In the 2 patients with primary RCC, tumor size remained unchanged but their pain improved, and their renal function was unchanged post SBRT. There was no significant treatment related side-effect.nnnCONCLUSIONSnPrecise high dose radiation can cause significant tumor cell death in radio-resistant metastases from RCC. It also offers excellent local control and symptom palliation, without significant toxicity. Therefore, SBRT may represent a novel non-invasive, nephron-sparing option for the treatment of primary RCC as well as extra-cranial metastatic RCC. A prospective clinical trial using SBRT for primary and metastatic RCC is on-going. No significant financial relationships to disclose.