Page 20

30114GA

fraction, for tumors of less than or equal to 4cm in size; fraction schedule 2: 42Gy in 3 fractions, for tumors of greater than 4cm in size (i.e. 14Gy per fraction, given in 3 fractions over a maximum of 3 weeks, each fraction given on non-consecutive days). SAbR in Locally Advanced RCC: A Bench to Bedside Case Report The application of SAbR may find a role in a subset of kidney cancer patients—those who present with inferior vena cava (IVC) tumor thrombus (IVC-TT) and comprise up to 10% of RCC patients. Surgery is the only treatment with proven efficacy for this setting, but such resection is difficult, and mortality and morbidity is high. Until recently, the difficulty with surgery has left clinicians with no treatment options for recurrent or unresectable RCC IVC-TT which left untreated can lead to Budd-Chiari syndrome. Our experience34 treating 2 RCC patients with Level IV IVC-TT, one with recurrent disease and the other unresectable— with SAbR —suggests how this modality may have utility in this difficult-to-treat setting. Our case report followed two elderly (75 years old and 83 years old) male patients both of whom had been refractory to systemic 76 Kidney Cancer Journal therapy. One received 50 Gy in 5 fractions and at 2 years of followup is doing well with a significant decrease in the enhancement and size of the IVC-TT. (Figures 3, 4) The second patient survived 18 months post SAbR. None of the patients that underwent SAbR to IVC-TT experienced any treatment-related toxicity. The survival of 18 months and 24 months for these patients is comparable to the reported median survival of 20 months in similar groups of patients who underwent surgical resection.20 Despite the high surgical mortality (10%) and morbidity (up to 30%), majority of the patients return with systemic metastasis perhaps from the tumor emboli shed from the IVC-TT itself.35 Therefore, an intriguing hypothesis raised by our study is whether SAbR could have further application in the neoadjuvant setting and whether it might lower the likelihood of systemic metastases by making the tumor emboli non-viable. A safety lead-in phase 2 clinical trial is addressing this issue where level II or higher IVC-TT is being radiated to 40Gy in 5 treatments immediately prior to surgery and looking at relapse-free survival at one year as the primary outcome measure. The target enrollment is 30 patients and the estimated completion date is December of 2018 for this trial with a ClinicalTrials.gov identifier of NCT02 473536.36 Figure 4. MRI of IVC Tumor Thrombus in clear cell RCC before and after SAbR. Coronal (top) and axial (bottom) contrast enhanced MR images at different time points during the course of treatment. After nephrectomy and thrombectomy, the patient had an intraluminal recurrence of tumor thrombus, which was adherent to the IVC wall (arrowheads, A). The superior extent of the thrombus is inferior to the diaphragm (Level III; arrow, A). Note the size of the thrombus at the level of the right hepatic vein (arrow, B). After systemic targeted therapy (C) there was obvious disease progression with thrombus extending superior to the diaphragm (level IV, arrow) and increased enhancement (arrowhead, C). Note marked increased in transverse diameter (arrow, D). Two years after SABR therapy there is persistent thrombus extending above the diaphragm (arrow, E) although exhibiting clear decrease in enhancement (arrowhead, E) and marked reduction in transverse diameter (arrow, F).


30114GA
To see the actual publication please follow the link above