Discordance of patient- and physician-reported toxicities in two prospective trials of stereotactic body radiotherapy (SBRT) for localized prostate cancer

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Background: SBRT for localized prostate cancer (PCa) is the focus of several ongoing and reported high-impact trials, which often focus on physician-reported toxicity (P-Tox) when comparing regimens. Patient-reported quality of life (PR-QoL) may differ and provide a more sensitive comparative metric of treatment burden, especially with fewer provider interactions during SBRT than during protracted RT courses. We evaluated the concordance of prospective genitourinary (GU) and gastrointestinal (GI) P-Tox and PR-QOL in men receiving SBRT for PCa. Methods: Data from two concurrently-enrolled prospective trials of SBRT in high-risk (Phase I Safety Endpoint, NCT01896271) and low-intermediate risk (Phase II GI Toxicity Endpoint, NCT02353832) PCa were used. Matching standardized schedules of collected PR-QoL [Expanded Prostate Cancer Index Composite (EPIC)] and P-Tox (CTCAE v5.0) were analyzed over the first 18 months of follow up, where symptoms are most pronounced. We assessed concordance of Grade≥2 GU/GI physician reported toxicity with PR-QoL declines exceeding anchor based minimal clinically important difference (MCID) thresholds (-6 urinary and -5 bowel summary scores, respectively) for each patient at each time point. Patients without baseline PR-QoL data were excluded in full, while time points with missing PR-QoL or P-Tox were excluded individually without imputation. Concordance was evaluated by Cohen’s kappa statistic. Results: From 101 patients, there were 256 (64%) follow up observations through 18 months with both PR-QoL and P-Tox at the time point and baseline. Concordance of PR-QoL and P-Tox was low at all time points for both GU and GI toxicity domains (mean kappa 0.093; Table). MCID was more often reported by patients than Grade≥2 toxicity by physicians (38% vs 17% for GU and 44% vs 10% for GI). There was little overlap of PR-QoL and P-Tox reporting: Grade≥2 P-Tox reported in 17% of observations with MCID in PR-QoL, while MCID in PR-QoL reported in 54% of observations of Grade ≥2 P-Tox. Mean concordance was similarly low when analyzing sub-groups of trial, investigator, and an alternative 2xMCID threshold. Conclusions: P-Tox and PR-QoL differed dramatically in two prospective studies of SBRT despite toxicity primary endpoints. This may reflect subjective and varying intervention thresholds driving P-Tox reporting, rather than actual patient burden. These data strongly support use of PR-QoL rather than P-Tox for SBRT comparative study endpoints and guidelines in this rapidly evolving space. [Table: see text]

A multi-institutional phase I/II trial of focal salvage high-dose-rate brachytherapy for locally recurrent prostate cancer in patients treated with prior radiotherapy (F-SHARP)

TPS265

Background: Approximately 20% of patients with localized prostate cancer who undergo curative-intent radiotherapy develop a clinical recurrence after radiation. Half of these clinical recurrences are a local radio-recurrence (LRR). Patients with LRR have multiple potential salvage local therapy options, but there are limited data guiding management. Prospective clinical trials demonstrate 5-year freedom from biochemical recurrence of ~50-70% with salvage brachytherapy using primarily whole-gland low dose rate or high dose rate (HDR) brachytherapy. However, the risk of severe grade ≥3 late toxicity is 5-15% in prior series, suggesting an opportunity to improve the therapeutic ratio. The F-SHARP trial was designed to study focal salvage HDR brachytherapy as a means to treat LRR after definitive radiotherapy and reduce the toxicity of re-irradiation. Methods: F-SHARP is a two-staged non-randomized phase I/II trial of focal salvage HDR brachytherapy for LRR prostate cancer. The study originated at a single center but will be opening at 3 other institutions in late 2020. Eligibility criteria include biopsy-proven local recurrence after curative radiation therapy (any form) for cT1-T3a N0 M0 prostate adenocarcinoma, no radiographic evidence of nodal or metastatic disease prior to enrollment on CT/MRI and bone scan (fluciclovine PET/CT encouraged), current IPSS ≤20, and no grade ≥3 CTCAE v 4.03 toxicity from prior RT. Initially, study HDR was delivered as a single fraction of up to 30 Gy to the target volume (gross recurrent tumor + 5 mm), with priority given to normal tissue constraints. Based on data in the definitive HDR brachytherapy setting suggesting inferior outcomes with single fraction HDR, a 2 fraction regimen (again delivering up to 30 Gy to the gross recurrent tumor + 5 mm) was added as an option as well. The primary endpoint is Grade ≥3 CTCAE V4.03 RT-related toxicity at 3 months. Assuming that the true toxicity rate in the population is 10% or less, the study has 81% power to reject the null hypothesis that the toxicity rate is 33% or higher. In the first stage, 7 patients will be accrued. If there are 2 or more toxic responses in these 7 patients, the study will be stopped for safety reasons. Otherwise, 17 additional patients will be accrued for a total of 24 patients to evaluate the primary endpoint. After completion of the 24 patient toxicity assessment, the cohort expands to 50 subjects to study freedom from biochemical recurrence (secondary endpoint). Other secondary endpoints include local control, freedom-from local failure, freedom from elsewhere-prostate control, freedom from distant metastasis, freedom from hormonal therapy, disease-free survival, cause-specific survival, and overall survival. The study has completed the initial 24 patient toxicity assessment and continues accrual in the expansion cohort. Clinical trial information: NCT03312972.

Trends in primary surgical resection and chemotherapy for metastatic colorectal cancer, 2000-2016

e16000

Background: When, whether and in whom resection of the primary tumor for patients with metastatic colorectal cancer (CRC) is indicated remains incompletely elucidated, although a recent randomized trial (JCOG1007, presented at GI ASCO 2020) showed no survival benefit in resection of asymptomatic primary tumors in this population. Given the emergence of multiagent chemotherapy, surgery may be used less, but patterns of care for metastatic CRC have not been reported. As such, we sought to evaluate trends in use of primary surgical resection and chemotherapy among patients with metastatic CRC. Methods: Patients diagnosed with metastatic CRC between 2000-2016 were identified from the Surveillance, Epidemiology and End Results (SEER) registry. Multivariable logistic regression defined odds of undergoing primary surgical resection, with year of diagnosis as the primary independent variable. The cohort analysis was also stratified by primary site (colon versus rectum), age ( < 50 vs. >50 years) and whether patients also underwent resection of metastatic sites (yes versus no). The secondary endpoint of interest was receipt of any chemotherapy, also assessed by multivariable logistic regression. Results: Among 99,835 patients with metastatic CRC, 55,527 (55.7%) underwent resection of their primary tumor. The odds of undergoing primary surgery decreased with later year of diagnosis, with patients diagnosed in 2016 61.1% less likely to undergo surgery than those diagnosed in 2000 (AOR 0.39, 95% CI 0.36-0.42, p < 0.0001; absolute percent 62.3% to 43.8%). Black patients and women were also less likely to have surgery (p < 0.001). Similar trends by year for primary surgery were observed among each of the subgroups, although patients with colon primary, young adults (age < 50), and patients also undergoing metastatectomy were more likely to undergo primary surgery (p < 0.001 for all). In contrast, the odds of receiving chemotherapy increased dramatically with later year of diagnosis, with patients diagnosed in 2016 221% more likely to receive chemotherapy than those diagnosed in 2000 (AOR 2.21, 95% CI 2.04 to 2.40, p < 0.0001; 45.5% to 64.0%). Conclusions: From 2000-2016, we observed a sharp decline in the rate of primary surgical resection for patients with metastatic CRC, while use of chemotherapy increased over the same period. Prospective studies are needed to define the optimal local treatment for patients with metastatic CRC, perhaps with stratification by molecular and clinical characteristics, in order to optimize both cancer-specific and symptomatic outcomes.

Outcomes of rectal cancer patients treated using Polish II neoadjuvant short course radiation therapy and chemotherapy approach in comprehensive cancer center

e16088

Background: Neoadjuvant short-course (SC) radiation (RT) followed by fluoropyrimidine based chemotherapy prior to surgery (Polish II approach) is a less utilized treatment in the United States for rectal cancer. Based on data suggesting equivalent or improved outcomes at lower cost compared to the long course neoadjuvant chemoradiation, our team started utilizing this approach for rectal cancer management at Simmons Comprehensive Cancer Center. We aim to document our experience with Polish II approach at NCI-designated comprehensive cancer center program. Methods: A retrospective review of stage I-IV rectal cancer patients, seen at an academic center or the Dallas County safety net hospital and treated at Simmons Comprehensive Cancer Center from Nov 2017 to Dec 2019. Patients were treated with neoadjuvant SC-RT followed by 3 cycles of FOLFOX prior to surgery and followed by adjuvant FOLFOX. Descriptive data for demographic, radiation, chemotherapy and surgery, hospitalizations, 30 day post-surgery admission, time to relapse, and laboratory parameters was collected. Results: Thirty-nine patients met the inclusion criteria (average age 58 years; 74% men/26% women). Forty-six percent of patients were Hispanic, 28.2% White, 15.4% African American and 7.7% Asian. The majority of patients had stage IIIB (46.2%), followed by IIIC (17.9%), IIA (12.8%), IIIA (7.7%), while rest were stage I, IVA or unknown (5.1%). All patients received 5 x 5 SC-RT, 100% completed 3 cycles of planned neoadjuvant FOLFOX (12.8% received 4-8 cycles) and 36/39 (92%) of patients underwent planned surgery. Median duration from SC-RT to chemotherapy was 12 days, and from chemotherapy to surgery was 37 days. Hospitalization occurred in 3 patients (7.7%) during neoadjuvant therapy, and in 8 patients (20.5%) within 30 days post-surgery. Complete pathological response was seen in 6 patients (16.6%) and near-complete pathological response in 3 patients (8.3%). Relapse occurred in 10.3% patients at time of data acquisition. Grade 3 and 4 neutropenia, anemia, and thrombocytopenia in neoadjuvant phase was observed in 8.6%, 25.7%, and 2.8% patients, respectively. Conclusions: In rectal cancer patients treated at a comprehensive cancer center, neoadjuvant Polish-II approach was feasible and well tolerated. Pathological response rates were comparable to historical data. SC-RT based neo-adjuvant therapy approach should be favored due to lower pelvic radiation dose, tolerance and convenience to patients.

Safety and outcome of stereotactic body radiation therapy (SBRT) with rectal hydrogel spacer for prostate cancer

76

Background: Ultra-hypofractionated radiotherapy delivered using stereotactic body radiotherapy (SBRT) is a cost-effective treatment for localized prostate cancer. Optimal dosing remains unclear, as commonly used 30-40Gy/5fx regimens appear to overestimate hypofractionation’s control benefits. Here, we report the largest experience of 45Gy/5Fx of SBRT for prostate cancer patients treated with hydrogel peri-rectal spacer (‘hydrogel’). Methods: An IRB-approved retrospective protocol was used to conduct a registry search identifying all patients with prostate cancer who received 45Gy/5Fx between 2015-2019 with hydrogel. Genitourinary (GU) and gastrointestinal (GI) toxicities were defined using the NCI Common Toxicity Criteria for Adverse Events (CTCAE) v.5.0. The ASTRO-Phoenix failure definition of Nadir+2 ng/mL was used for biochemical failure. Results: We analyzed 250 low (9.2%), intermediate (85.2%), and high-risk (5.6%) prostate cancer patients with a median follow-up of 9.9 months (range: 0-45.7 months). Acute GU and GI grade ≥ II toxicities were noted in 15.2% and 7.2% of patients, respectively. Late GU grade II and III toxicities occurred in 24.0% and 1.2% of patients, respectively, while late GI grade II and III toxicities occurred in 4.0% and 0.4% of patients, respectively. In patients (N=44) with follow-up >2 years, late GU and GI grade III toxicities occurred in 4.55% and 2.27% of patients, respectively. A significant correlation was noted for acute GI and GU toxicity predicting the respective late GI and GU toxicity (p-value < 0.001 for both). Physician-reported Grade ≥ II new onset erectile dysfunction was 17.2%. A gradual decline in prostate-specific antigen with a mean nadir of 0.04 (95% CI: [0.018, 0.067]) at 36 months was noted. The actuarial freedom from biochemical failure was 96.33% at 3 years. Overall survival was 94.09% at 3 years with no deaths attributed to prostate cancer. Conclusions: SBRT treatment of 45Gy/5Fx with hydrogel is well tolerated with GU/GI toxicities comparable to those reported for conventional fractionation. Although short, the 3-year biochemical control rate is encouraging. Longer follow-up and prospective evaluation are warranted.

Combination of dual immune checkpoint inhibition (ICI) with stereotactic radiation (SBRT) in metastatic renal cell carcinoma (mRCC) (RADVAX RCC)

614

Background: Dual ICI with nivolumab/ipilimumab (N/I) has become a standard of care (SOC) for patients (pts) with mRCC. Since the failure to respond to ICI may be due to a lack of immune recognition, novel vaccination approaches and stimulation of the innate immune system (e.g. stimulator of interferon genes (STING) agonists) are being pursued in clinical trials. Because preclinical studies using SBRT have demonstrated the a.) release of tumor antigens, b.) STING pathway activation and c.) synergy with ICI, we have conducted a study to explore the safety and efficacy of this approach in mRCC pts. Methods: Pts with clear cell mRCC were screened and enrolled at two sites (UT Southwestern and Johns Hopkins). Prior treatment with tyrosine kinase inhibitors (TKI) and IL2 were allowed. Enrolled pts received standard of care dosing with Nivolumab (3 mg/kg) and Ipilimumab (1mg/kg) IV q3weeks followed by nivolumab monotherapy. SBRT was administered to 1-2 disease sites with a dose of 50 Gy in 5 fractions between the first and the second dose of N/I. The primary goals of this exploratory study were to determine the safety and tolerability as well as the objective response rate (ORR) by RECIST 1.1 of non-irradiated lesions. Results: A total of 29 pts were screened and 25 pts were enrolled. 11 (44%) of pts received at least one prior systemic therapy: 4 (16%) pts received IL2 and 7 (28%) TKI therapy. The cohort was primarily intermediate and poor risk pts (favorable risk n = 2 (8%), intermediate risk n = 20 (80%), poor risk n = 3 (12%)). 10 (40%) pts required immune suppressive therapy with prednisone for classic immune related adverse events as seen with dual ICI. Radiation pneumonitis limited to the radiation field (grade 2) was seen in 2 pts and responded promptly to oral steroids. At the time of analysis, partial responses (PR) were observed in 14/25 patients with an ORR of 56%. Additional analyses including duration of response, progression free survival and overall survival will be presented. Conclusions: Dual ICI with SBRT showed an acceptable safety and encouraging antitumor activity in mRCC warranting further investigations. Clinical trial information: NCT03065179.

Prostate oncologic therapy while ensuring neurovascular conservation (POTEN-C): A phase II randomized controlled trial of stereotactic ablative body radiotherapy (SAbR) with or without neurovascular sparing for erectile function preservation in localized prostate cancer

TPS381

Background: Radiotherapy (RT) associated sexual dysfunction occurs in half of men following treatment for localized prostate cancer. Proposed mechanisms include vascular injury of adjacent internal pudendal arteries (IPA), penile bulb (PB), corpora cavernosa (CC) or neurovascular bundles (NVB). Ability to spare these structures has been limited by a presumed need to treat the entire prostate gland, while also preventing rectal injury. Recent innovations have challenged this issue: a) precise dose delivery with stereotactic ablative RT (SAbR), b) improved spatial mapping of clinically significant disease with mpMRI, c) rectal avoidance with rectal spacer use. Methods: POTEN-C is a multi-center phase II randomized control trial, which includes men with a) low-intermediate risk prostate cancer eligible for SAbR without ADT, b) potent by sexual composite score ≥60 on EPIC patient-reported quality of life instrument, c) mpMRI delineated disease (PIRADS v2 score 3-5) ≥5mm to at least one ‘spared’ NVB. After placement of rectal spacer gel and CT/MRI simulation, men are randomized to standard SAbR to 40-45Gy/5fx or neurovascular-sparing SAbR. In the sparing experimental arm, the prostate PTV is given 30Gy/5fx excluding unilateral ‘spared’ NVB, while a 40-45Gy PTV further excludes a 5mm protective shell on the unilateral ‘spared’ NVB+IPA+PB+CC. Centralized rapid review of initial contours/plans and online training materials are integrated. The primary endpoint is 2-year patient-reported potency, measured by EPIC sexual composite score. We hypothesize that neurovascular sparing SAbR will reduce 2-year EPIC score decline from a control of 20 to 10 (corresponding to a MCID). Assuming standard deviation 20, two-sided significance level 0.10 with two-sample t-testing, and 15% attrition, we intend to enroll 120 patients to provide 80% power to detect this difference. Secondary endpoints include sexual medication/aid use, relapse rates, GU/GI toxicity. Enrollment is ongoing. Details: http://www.poten-c.org . Clinical trial information: 03525262.

Stage-specific conditional survival among young versus older adults with colorectal cancer in the United States, 2004-2010

257

Background: Conditional survival (CS) is a relevant prognostic measure for cancer survivors and physicians and may be particularly important for young adult patients with CRC (colorectal cancer), whose incidence is rising. We sought to compare CS among young versus older adults with CRC. Methods: Patients diagnosed with colon or rectal adenocarcinoma between 2004-2010 were identified from the Surveillance, Epidemiology and End Results (SEER) registry. Overall survival (OS) and cancer-specific survival (CSS) were estimated, along with smoothed yearly hazards of death due to CRC, other causes and any cause, stratified by age at diagnosis ( < 50 vs. >50 years). Stage-specific conditional 5-year OS and 5-year CSS given that patients had already survived 1, 2, 3, 4 or 5 years after diagnosis was calculated, also stratified by age. Results: Among 161,859 patients with median follow-up of 54 months, 35,411 (21.9%) were aged < 50 years. Both OS and CSS were superior among younger adult as compared to older adult patients (p < 0.001). For older adults with rectal cancer, hazards of death due to non-cancer causes exceeded that of rectal and colon cancer approximately 6 and 4.5 years after diagnosis, respectively. Among younger adults, hazard of death from cancer remained greater than death from other causes throughout the entire study interval. Patients experienced improved conditional survival over time with greater improvement seen for more advanced stages. However, young adults had less CS improvement over time than older adults. For example, the 5-year overall and CSS for Stage IV colon cancer improved from 7.4% to 52.4%% (OS) and 15.1% to 78.5% (CSS) 0 to 5 years after diagnosis for older adults. In contrast, for younger adults, the 5-year overall and CSS for Stage IV colon cancer improved from 15.6% to 57% (OS) and 19.3% to 68.4% (CSS). Conclusions: Prognosis for CRC improves over time for all patients, although the increase in survival appears to be less for younger than older adults. Up to 10 years after diagnosis, the primary cause of death in younger adults with CRC remains their incident cancer.

Patterns of relapse and second malignancy after adjuvant external beam radiation therapy for stage I-II seminoma

428

Background: To determine relapse rate, patterns of relapse and risk of second malignancy (SM) from a large single institution experience of adjuvant external beam radiation therapy (RT) for stage I-II seminoma. Methods: 463 patients with clinical stage I (n = 339) and II (n = 124) seminoma underwent adjuvant RT (median 25.5Gy) between 2/1990 and 11/2015. Data was gathered by retrospective chart review. Patients with > 5 years of follow-up (n = 312) were included in analysis of SM risk. Of stage II patients, 72% (89/124) received a boost to gross disease (median 4.5Gy). Field design was para-aortic nodal region only (n = 96), para-aortic and ipsilateral pelvic nodal region (n = 351) or para-aortic and bilateral pelvic nodal region (n = 8). Field design was not available for 8 patients. Patients were followed with clinical exam, serial imaging, and tumor markers. Relapse and SM were confirmed pathologically. Results: At median follow-up of 7.9 years, there were 20 relapses (median 13.2 months; range 2.5-55.3 months). There were 9 and 11 relapses in stage I and II patients, respectively, with 7/20 (35%) occurring > 2 years after RT. Relapses were identified by clinical symptoms (n = 7), imaging (n = 9), or elevated serum markers (n = 4). Sites of relapses included the lung/mediastinum (n = 10), retroperitoneum/pelvis (n = 5), bone (n = 3) and inguinal nodes (n = 2). 15 (3 pelvic) occurred after para-aortic and ipsilateral pelvic lymph node RT, while 5 (2 pelvic) occurred after para-aortic RT alone. 19/20 patients received cisplatin-based chemotherapy for relapse and were without evidence of disease at last follow-up (median 123 months). Of 35 total non-testicular SM (33 patients), 17 (48.6%) were in the RT field, 4 (11.4%) were marginal and 14 (40%) were out of field. Common SM were prostate (10), lymphoma (4), bladder (3) and kidney (3). The 5 and 10 year overall survival for the cohort is 99.2% and 97.9%, respectively. Conclusions: Stage I-II seminoma patients have a low risk of relapse and SM following adjuvant RT. Relapse is less common in patients treated with para-aortic and pelvic fields. More than 1/3 of relapses occur more than 2 years after adjuvant RT, necessitating long term clinical, radiographic and biochemical follow-up.

Template-based high dose rate endobronchial brachytherapy for palliation of previously irradiated obstructive lung lesions

174

Background: Local progression after external beam radiation therapy (RT) for lung cancer may result in clinical compromise from bleeding and/or airway obstruction, and additional RT may be precluded by radiation tolerance. High-dose-rate (HDR) endobronchial brachytherapy (EBT) is an effective salvage treatment for airway obstruction and/or bleeding, but requires significant time and resources; planning and treatment are performed bronchoscopically under anesthesia. We sought to reduce procedure and anesthesia time for EBT through template-based planning. Methods: EBT templates were created using the Brachyvision version 11.0.47 treatment planning system for the Varisource iX Ir-192 afterloader. Plans were optimized for dose uniformity at distance from the source following planning criteria of published works. Nine endobronchial centering tube templates were created for treatment lengths from 2-10 cm (1cm intervals) prescribed to 0.5cm distance from the applicator surface. Results: Standard EBT treatment requires a median of 47 minutes (range 44-49 minutes); 5 minutes for applicator placement and fluoroscopic confirmation, 15-17 minutes for plan design and optimization, 20 minutes for quality assurance and plan check, 2-5 minutes for radiation delivery, and 2 minutes for room clearance and applicator removal. Pre-planned templates were evaluated for plan quality, and achieved >90% of the prescription dose for the entire treatment length at the respective treatment depth. Changes to the prescription dose could be achieved through dwell time scaling. Changes to the prescription depth require re-optimization of the plan with the current templates as a base. Use of template-based planning was expected to reduce overall treatment time by 8-9 minutes (16-20% reduction in overall procedure time, 50-56% reduction in treatment planning time); median observed treatment time was 35 minutes (range 32-38 minutes). Conclusions: Template-based HDR EBT treatment plans were developed for the palliative lung cancer program at our institution. Implementation of template-based plans resulted in reduced procedure and operative time, and are now our standard technique.

Radiation therapy for palliation of osseous metastasis from hepatocellular carcinoma

204

Background: Osseous metastasis from hepatocellular carcinoma (HCC) is uncommon, and optimal palliative management for palliation is unclear. We present our clinical experience with palliative radiotherapy (RT) for osseous metastasis from HCC. Methods: Patients were identified using two prospectively maintained databases at our institution: all patients with HCC who developed metastases and all patients undergoing RT. Medical records were retrospectively reviewed following Institutional Review Board approval. We identified 146 patients with metastatic HCC, of which 28 patients with 38 osseous metastases were eligible for this analysis. All patients are seen in a multi-disciplinary clinic where consensus for management is developed. Most (89%) had metastasis at the time of initial tumor diagnosis, including 22 (79%) patients with osseous lesions at diagnosis. Tissue confirmation of metastasis was obtained in 22 (79%) patients. Outcomes of interest included patient-reported pain relief at time of follow-up, radiographic response at 6-12 months, and overall survival. Statistical analysis was performed with SPSS (IBM Corporation). Results: Median age at diagnosis was 61 years, and 86% (n = 24) were male. The most common site of metastasis was vertebral body (n = 26, 70%). Median time from bone metastasis diagnosis to RT was 1 month (range, 0-20). Only 1 patient received concomitant systemic therapy at the time of RT. Metastases were most commonly treated using 2D techniques (n = 26, 68%) to 30 Gy in 10 fractions (n = 18, 47%). Pain relief was complete, partial, and absent for 8 (21%), 24 (63%), and 6 (16%) metastases, respectively; no patient reported an increase in pain after treatment. Prescription BED3 > 50 Gy was associated with improved local control (P = .03). 7 (18%) radiographic local failures were observed at a median time of 5.4 months, and the 6-month local failure rate was 20.2%. Median survival was 3.4 months, with a 6-month survival rate of 39.1%. Conclusions: Mortality for patients with osseous metastasis from HCC is high, but palliative RT is associated with significant pain relief and/or disease control in many patients. This data on efficacy of palliative RT helps guide optimal management of these patients.

Patterns of failure and morbidity associated with palliative intervention in patients with malignant biliary obstruction

71

Background: Outcome for patients with malignant biliary obstruction is poor. While endoscopic or percutaneous procedures provide palliative benefit, stents often occlude or migrate, and drains frequently fail requiring repeat procedures in medically fragile patients. As part of a multidisciplinary effort to improve outcomes in this population, we undertook an investigation to determine rates of stent and drain failure and morbidity to identify areas of potential improvement. Methods: After Institutional Review Board approval, retrospective review of all cancer registry patients undergoing percutaneous or endoscopic intervention for biliary obstruction from 1/2004-10/2014 and billing reports from 11/2012-10/2014 identified 230 patients. Cases of biliary obstruction due to malignancy requiring intervention were selected, resulting in 94 evaluable patients. Charts were reviewed to determine dates and cause for stent and/or drain replacement and morbidity. Results: Of 94 analyzable patients, median age was 60 years and 49 were male (52%). Malignant cause of obstruction was gastric/colorectal in 16 (17%), biliary in 37 (39%), hepatocellular in 7 (7%), and pancreatic in 34 (36%). Stenting was part of the initial procedure in 47 (50%), and drain placement in 49 (52%). Ultimately 60 (64%) patients underwent stent procedures and 82 (87%) patients required drains. Of the stented patients, 27 (45%) required repeat stenting, and 13 (22%) required > 1 stent replacement. Of the patients who underwent drainage procedures, 68 (83%) required repeat drainage, and 52 (63%) required > 1 repeat drainage procedure. Cholangitis was observed following stent in 5 (5%) of patients, 60% in patients undergoing > 1 stent procedures. Median survival after initial procedure was 12 months; for patients requiring repeat procedures, median survival was 4.5 months. Conclusions: Malignant biliary obstruction is a morbid disease with high rates of reocclusion requiring repeat procedures, which may negatively impact outcome and increase healthcare cost. Efforts to reduce the rates of repeat procedures are critical to address this clinical need.

Outcomes and toxicity for hypofractionated and single-fraction image-guided stereotactic radiosurgery for sarcoma metastatic to the spine

9501

Background: Conventional radiation treatment (20-40 Gy total dose, 5-20 fractions, 2-5 Gy per fraction) for sarcoma metastatic to the spine provides subtherapeutic doses and results in poor local control (58-77% at 1 year). Hypofractionated (HF) and/or single-fraction (SF) image-guided stereotactic radiosurgery (IG-SRS) may provide a more effective means of control and salvage for these lesions. Methods: Patients with pathologically-proven high-grade sarcoma metastatic to the spine treated with HF and SF IG-SRS were included. Local control (LC) and overall survival (OS) were analyzed using Kaplan-Meier statistics; univariate/multivariate analyses were performed using Cox regression. Toxicities were assessed according to CTCAE v4.0 criteria. Results: From 5/2005 and 11/2012, 88 patients with 120 discrete metastases were treated with HF (3-6 fractions, median dose 28.5 Gy; n=52, 43.3%) or SF IG-SRS (median dose 24 Gy, n=68, 56.7%). Median followup was 12.3 months. LC at 12 months was 87.9% (95% CI 81.3-94.5%). OS at 12 months was 60.6% (95% CI 49.6-71.6%) with a median survival of 16.9 months. SF IG-SRS demonstrated superior LC to HF IG-SRS (P=.007) (Table). SF IG-SRS retained its significance in terms of improved LC on multivariate analysis, HR 0.304 (95% CI: 0.117-0.790); variables tested included prior radiation therapy, histology, IG-SRS fractionation, surgery, and chemotherapy. Treatment was well-tolerated with 1% acute Grade 3 toxicity and 4.5% chronic Grade 3 toxicity observed; there were no > Grade 3 toxicities. Conclusions: In the largest series of metastatic sarcoma to the spine to date, image-guided stereotactic radiosurgery provides excellent local control in the setting of an aggressive disease with low radiation sensitivity and poor prognosis. Single-fraction image-guided stereotactic radiosurgery demonstrates the highest rates of local control with minimal toxicity. [Table: see text]