Practical Implications of the American Society for Radiation Oncology Radiation Oncology Case Rate Program Proposal for Radiation Oncologists.

The American Society for Radiation Oncology has proposed the Radiation Oncology Case Rate Program (ROCR) to advocate for fair reimbursement for radiation oncologists. ROCR would replace Medicare fee-for-service with a case rate payment for each of the 15 most common cancer types treated with external beam or stereotactic radiation therapy. This topic discussion attempts to provide a concise overview of the practical implications for radiation oncologists should the ROCR payment program be legislated by Congress and subsequently implemented by the Center for Medicare and Medicaid Services. This topic discussion covers the practical changes to billing and reimbursement, the Health Equity Achievement in Radiation Therapy payment, the Quality of Care requirement, and the available tool to calculate the effect of the ROCR based on an individual practice's case mix.

Recent Trends in Medicare Payments for Outpatient Cancer Care at the End of Life.

PURPOSE: Outpatient care for patients with cancer compromises 60% to 70% of health care costs during the last 6 months of life. Recent approvals for expensive biologics and growing support for lower-cost hypofractionated radiation therapy in the palliative management of advanced cancer have introduced offsetting spending effects on end-of-life care that may shift overall expenditures for this patient cohort. METHODS AND MATERIALS: In this descriptive retrospective cohort study, end-of-life care is defined as the aggregate of medical services and supplies, including drugs, furnished to patients with cancer in the outpatient setting during the last 6 months of life. A total of 84,744 Medicare beneficiaries with a cancer diagnosis were identified as having died between January 1, 2016, and December 31, 2019. Beneficiaries with Medicare Advantage were not included in this study. Medicare Standard Analytical Files were abstracted for all paid claims for these beneficiaries during the last 6 months of life, and provider payments were summed according to service or supply category and year of death. Comparisons of service and supply utilization and costs between patient groups were performed using the Pearson χ2 test. RESULTS: The average total Medicare Part B payments per treated beneficiary during the last 6 month of life increased by 12.0% between 2016 and 2019 (from $14,487 to $16,227), with the greatest absolute cost increase observed for the medical oncology category (from $7030 to $9436 [+34.2%]). Within the medical oncology category, drug utilization shifted away from less costly chemotherapy and hormone therapy agents and toward more expensive immunotherapy agents. The increase in immunotherapy utilization and drug costs alone accounted for 84% of the increase in total Part B payments for all categories during the period. CONCLUSIONS: Although costs related to end-of-life care for nearly all cost categories have remained relatively stable, oncology drug costs overall and immunotherapy costs specifically have accelerated and account almost entirely for the observed overall increase in outpatient cost burden for Medicare.

A Medicare Claims Analysis of Racial and Ethnic Disparities in the Access to Radiation Therapy Services.

PURPOSE: Reduced access and utilization of radiation therapy (RT) is a well-documented healthcare disparity observed among racial and ethnic minority groups in the USA and a contributor to the inferior health outcomes observed among Black, Hispanic, and Native American patient groups. What is less understood are the points during the process of care following RT consultation at which patients either fail to complete their prescribed treatment or encounter delays. Identification of those points where significant differences exist among different patient groups may help identify opportunities to close gaps in the access of clinically indicated RT. METHODS AND MATERIALS: This analysis examines 261,559 RT episodes abstracted from Medicare claims and beneficiary data between 2016 and 2018 to determine rates of treatment initiation following planning and timeliness of treatment completion for different racial groups. RESULTS: Failure to initiate treatment was observed to be 29.3% relatively greater for Black, Hispanic, and Native American patients than for White and Asian patients. Among episodes for which treatment was initiated, Black and Hispanic patients were observed to require a significantly greater number of calendar days (when adjusted for fraction number) for completion than for White, Asian, and Native American patients. CONCLUSIONS: There appears to be a patient cohort for which RT disparities may be more marginal in their effects-allowing for access to consultation and treatment prescription but not for treatment initiation or timely completion of treatment-and may therefore permit effective solutions to help address current differences in cancer outcomes.

Toxicity After Stereotactic Body Radiation Therapy for Prostate Cancer in Patients With Inflammatory Bowel Disease: A Multi-institutional Matched Case-Control Series.

PURPOSE: To evaluate the safety of stereotactic body radiation therapy (SBRT) for prostate cancer in men with inflammatory bowel disease (IBD). METHODS AND MATERIALS: We queried a consortium database for patients with IBD receiving SBRT for prostate cancer between 2006 and 2012. Identified patients were matched with patients without a history of IBD in a 3:1 fashion based on dose, fractionation, use of androgen deprivation therapy, and age distribution. Logistic regression was used to evaluate the association between having IBD and experiencing acute and late gastrointestinal (GI) and genitourinary (GU) toxicities as scored on the Common Terminology Criteria for Adverse Events scale. Time to late toxicity was evaluated using proportional hazard Cox models. Our study was limited by absence of data on prostate size, baseline International Prostate Symptom Score, and rectal dose-volume histogram parameters. RESULTS: Thirty-nine patients with flare-free IBD at time of treatment (median follow-up 83.9 months) and 117 matched controls (median follow-up 88.7 months) were identified. A diagnosis of IBD was associated with increased odds of developing any late grade GI toxicity (odds ratio [OR] 6.11, P <.001) and GU toxicity (odds ratio 6.14, P < .001), but not odds of developing late grade ≥2 GI (P = .08) or GU toxicity (P = .069). Acute GI and GU toxicity, both overall and for grade ≥2 toxicities, were more frequent in men with IBD (P < .05). Time to late GI and GU toxicity of any grade was significantly shorter in patients with IBD (P < .001). Time to late grade ≥2 GU, but not grade ≥2 GI toxicity, was also shorter in patients with IBD (P = .044 for GU and P = .144 for GI). CONCLUSIONS: Patients with IBD who received SBRT for PCa had a higher likelihood of developing acute GI and GU toxicity, in addition to experiencing lower grade late toxicities that occurred earlier. However, patients with IBD did not have a higher likelihood for late grade ≥2 GI or GU toxicity after SBRT compared with the control cohort. Interpretation of this data are limited by the small sample size. Thus, men with IBD in remission should be properly counseled about these risks when considering SBRT.

Disproportionate Negative Impact of the Radiation Oncology Alternative Payment Model on Rural Providers: A Cost Identification Analysis of Medicare Claims.

PURPOSE: The Radiation Oncology Alternative Payment Model (APM) is a Medicare demonstration project that will test whether prospective bundled payments to a randomly selected group of physician practices, hospital outpatient departments, and freestanding radiation therapy centers reduce overall expenditures while preserving or enhancing the quality of care for beneficiaries. The Model follows a complicated pricing methodology that blends historical reimbursements for a defined set of services made to professional and technical providers to create a weighted payment average for each of 16 cancer types. These averages are then adjusted by various factors to determine APM payments specific to each participating provider. METHODS: This impact study segregates APM participants into rural and urban groups and analyzes the effect of the Radiation Oncology Alternative Payment Model on their fee-for-service reimbursements. RESULTS: The main findings of this study are (1) the greater net-negative revenue impact on rural facilities versus urban facilities that would have participated in the Model this year and (2) the relative lack of high-value treatment services (ie, stereotactic radiotherapy and brachytherapy) delivered by rural facilities that exacerbates their negative impact. CONCLUSION: As such, rural providers participating in the Model in its current form may face greater risk to their economic viability and greater difficulty in funding technology improvements necessary for the achievement of high-quality care compared with their urban counterparts.

Drivers of Medicare Spending: A 15-Year Review of Radiation Oncology Charges Allowed by the Medicare Physician/Supplier Fee-for-Service Program Compared With Other Specialties.

PURPOSE: In 2019, the Centers for Medicare and Medicaid Services proposed a new radiation oncology alternative payment model aimed at reducing expenditures. We examined changes in aggregate physician Medicare charges allowed per specialty to provide contemporary context to proposed changes and hypothesize that radiation oncology charges remained stable through 2017. METHODS AND MATERIALS: Medicare physician/supplier utilization, program payments, and balance billing for original Medicare beneficiaries, by physician specialty, were analyzed from 2002 to 2017. Total allowed charges under the physician/supplier fee-for-service program, inflation-adjusted charges, and percent of total charges billed per specialty were examined. We adjusted for inflation using the consumer price index for medical care from the US Bureau of Labor Statistics. RESULTS: Total allowed charges increased from $83 billion in 2002 to $138 billion in 2017. The specialties accounting for the most charges billed to Medicare were internal medicine and ophthalmology. Radiation oncology charges accounted for 1.2%, 1.6%, and 1.4% of total charges allowed by Medicare in 2002, 2012, and 2017, respectively. Radiation oncology charges allowed increased 44% from 2002 to 2012 ($987.6 million to $1.42 billion) but decreased by 19% from 2012 to 2017 ($1.15 billion), adjusted for inflation. Total charges allowed by internal medicine decreased 2% from 2002 to 2012 ($8.53 to $8.36 billion), adjusted for inflation, and decreased 16% from 2012 to 2017 ($7.05 billion). When adjusting for inflation, ophthalmology charges increased 18% from 2002 to 2012 ($4.53 to $5.36 billion) and increased 3% from 2012 to 2017 ($5.5 billion). CONCLUSIONS: Radiation oncology physician charges represent a small fraction of total Medicare expenses and are not a driver for Medicare spending. Aggregate inflation-adjusted charges by radiation oncology have dramatically declined in the past 5 years and represent a stable fraction of total Medicare charges. The need to target radiation oncology with cost-cutting measures may be overstated.

Gantry-Mounted Linear Accelerator-Based Stereotactic Body Radiation Therapy for Low- and Intermediate-Risk Prostate Cancer.

PURPOSE: To establish the safety and efficacy of gantry-mounted linear accelerator-based stereotactic body radiation therapy (SBRT) for low- and intermediate-risk prostate cancer. METHODS: We pooled 921 patients enrolled on 7 single-institution prospective phase II trials of gantry-based SBRT from 2006 to 2017. The cumulative incidences of biochemical recurrence (defined by the Phoenix definition) and physician-scored genitourinary (GU) and gastrointestinal (GI) toxicities (defined per the original trials using Common Terminology Criteria for Adverse Events) were estimated using a competing risk framework. Multivariable logistic regression was used to evaluate the relationship between late toxicity and prespecified covariates: biologically effective dose, every other day versus weekly fractionation, intrafractional motion monitoring, and acute toxicity. RESULTS: Median follow-up was 3.1 years (range, 0.5-10.8 years). In addition, 505 (54.8%) patients had low-risk disease, 236 (25.6%) had favorable intermediate-risk disease, and 180 (19.5%) had unfavorable intermediate-risk disease. Intrafractional motion monitoring was performed in 78.0% of patients. The 3-year cumulative incidence of biochemical recurrence was 0.8% (95% confidence interval [CI], 0-1.7%), 2.2% (95% CI, 0-4.3%), and 5.1% (95% CI, 1.0-9.2%) for low-, favorable intermediate-, and unfavorable intermediate-risk disease. Acute grade ≥2 GU and GI toxicity occurred in 14.5% and 4.6% of patients, respectively. Three-year cumulative incidence estimates of late grade 2 GU and GI toxicity were 4.1% (95% CI, 2.6-5.5%) and 1.3% (95% CI, 0.5-2.1%), respectively, with late grade ≥3 GU and GI toxicity estimates of 0.7% (95% CI, 0.1-1.3%) and 0.4% (95% CI, 0-0.8%), respectively. The only identified significant predictors of late grade ≥2 toxicity were acute grade ≥2 toxicity (P < .001) and weekly fractionation (P < .01), although only 12.4% of patients were treated weekly. CONCLUSIONS: Gantry-based SBRT for prostate cancer is associated with a favorable safety and efficacy profile, despite variable intrafractional motion management techniques. These findings suggest that multiple treatment platforms can be used to safely deliver prostate SBRT.

Multi-Institutional Analysis of Prostate-Specific Antigen Kinetics After Stereotactic Body Radiation Therapy.

PURPOSE: Understanding prostate-specific antigen (PSA) kinetics after radiation therapy plays a large role in the management of patients with prostate cancer (PCa). This is particularly true in establishing expectations regarding PSA nadir (nPSA) and PSA bounces, which can be disconcerting. As increasingly more patients are being treated with stereotactic body radiation therapy (SBRT) for low- and intermediate-risk PCa, it is imperative to understand the PSA response to SBRT. METHODS AND MATERIALS: PSA data from 5 institutions were retrospectively analyzed for patients with localized PCa treated definitively with SBRT alone from 2004 to 2016. Patients received 35 to 40 Gy in 5 fractions, per institutional standards. Patients who had less than 12 months of PSA data or received androgen deprivation therapy were excluded from this study. Linear and logistic multivariable analysis were performed to identify predictors of nPSA, bounce, and biochemical recurrence, and joint latent class models were developed to identify significant predictors of time to biochemical failure. RESULTS: A total of 1062 patients were included in this study. Median follow-up was 66 months (interquartile range [IQR], 36.4-89.9 months). Biochemical failure per the Phoenix criteria occurred in 4% of patients. Median nPSA was 0.2 ng/mL, median time to nPSA was 40 months, 84% of patients had an nPSA ≤0.5 ng/mL, and 54% of patients had an nPSA ≤0.2 ng/mL. On multivariable analysis, nPSA was a significant predictor of biochemical failure. Benign PSA bounce was noted in 26% of patients. The median magnitude of PSA bounce was 0.52 ng/mL (IQR, 0.3-1.0 ng/mL). Median time to PSA bounce was 18.1 months (IQR, 12.0-31.1 months). On multivariable analysis, age and radiation dose were significantly associated with a lower incidence of bounce. Joint latent class models modeling found that nPSA and radiation dose were significantly associated with longer time to biochemical failure. CONCLUSIONS: In this multi-institutional cohort of patients with long-term follow-up, we found that SBRT led to low nPSAs. In turn, lower nPSAs are associated with reduced incidence of, and longer time to, biochemical failure. Benign PSA bounces occurred in a quarter of patients, as late as several years after treatment. Further studies are needed to directly compare the PSA response of patients who receive SBRT versus other treatment modalities.

Long-term Outcomes of Stereotactic Body Radiotherapy for Low-Risk and Intermediate-Risk Prostate Cancer.

Importance: Stereotactic body radiotherapy harnesses improvements in technology to allow the completion of a course of external beam radiotherapy treatment for prostate cancer in the span of 4 to 5 treatment sessions. Although mounting short-term data support this approach, long-term outcomes have been sparsely reported. Objective: To assess long-term outcomes after stereotactic body radiotherapy for low-risk and intermediate-risk prostate cancer. Design, Setting, and Participants: This cohort study analyzed individual patient data from 2142 men enrolled in 10 single-institution phase 2 trials and 2 multi-institutional phase 2 trials of stereotactic body radiotherapy for low-risk and intermediate-risk prostate cancer between January 1, 2000, and December 31, 2012. Statistical analysis was performed based on follow-up from January 1, 2013, to May 1, 2018. Main Outcomes and Measures: The cumulative incidence of biochemical recurrence was estimated using a competing risk framework. Physician-scored genitourinary and gastrointestinal toxic event outcomes were defined per each individual study, generally by Radiation Therapy Oncology Group or Common Terminology Criteria for Adverse Events scoring systems. After central review, cumulative incidences of late grade 3 or higher toxic events were estimated using a Kaplan-Meier method. Results: A total of 2142 men (mean [SD] age, 67.9 [9.5] years) were eligible for analysis, of whom 1185 (55.3%) had low-risk disease, 692 (32.3%) had favorable intermediate-risk disease, and 265 (12.4%) had unfavorable intermediate-risk disease. The median follow-up period was 6.9 years (interquartile range, 4.9-8.1 years). Seven-year cumulative rates of biochemical recurrence were 4.5% (95% CI, 3.2%-5.8%) for low-risk disease, 8.6% (95% CI, 6.2%-11.0%) for favorable intermediate-risk disease, 14.9% (95% CI, 9.5%-20.2%) for unfavorable intermediate-risk disease, and 10.2% (95% CI, 8.0%-12.5%) for all intermediate-risk disease. The crude incidence of acute grade 3 or higher genitourinary toxic events was 0.60% (n = 13) and of gastrointestinal toxic events was 0.09% (n = 2), and the 7-year cumulative incidence of late grade 3 or higher genitourinary toxic events was 2.4% (95% CI, 1.8%-3.2%) and of late grade 3 or higher gastrointestinal toxic events was 0.4% (95% CI, 0.2%-0.8%). Conclusions and Relevance: In this study, stereotactic body radiotherapy for low-risk and intermediate-risk disease was associated with low rates of severe toxic events and high rates of biochemical control. These data suggest that stereotactic body radiotherapy is an appropriate definitive treatment modality for low-risk and intermediate-risk prostate cancer.

Patient-reported quality of life after stereotactic body radiation therapy versus moderate hypofractionation for clinically localized prostate cancer.

BACKGROUND AND PURPOSE: Evaluate changes in bowel, urinary and sexual patient-reported quality of life following treatment with moderately hypofractionated radiotherapy (<5Gray/fraction) or stereotactic body radiation therapy (SBRT;5-10Gray/fraction) for prostate cancer. MATERIALS AND METHODS: In a pooled multi-institutional analysis of men treated with moderate hypofractionation or SBRT, we compared minimally detectable difference in bowel, urinary and sexual quality of life at 1 and 2years using chi-squared analysis and logistic regression. RESULTS: 378 men received moderate hypofractionation compared to 534 men who received SBRT. After 1year, patients receiving moderate hypofractionation were more likely to experience worsening in bowel symptoms (39.5%) compared to SBRT (32.5%; p=.06), with a larger difference at 2years (37.4% versus 25.3%, p=.002). Similarly, patients receiving moderate fractionation had worsening urinary symptom score compared to patients who underwent SBRT at 1 and 2years (34.7% versus 23.1%, p<.001; and 32.8% versus 14.0%, p<.001). There was no difference in sexual symptom score at 1 or 2years. After adjusting for age and cancer characteristics, patients receiving SBRT were less likely to experience worsening urinary symptom scores at 2years (odds ratio: 0.24[95%CI: 0.07-0.79]). CONCLUSIONS: Patients who received SBRT or moderate hypofractionation have similar patient-reported change in bowel and sexual symptoms, although there was worse change in urinary symptoms for patients receiving moderate hypofractionation.

Multinational Prospective Study of Patient-Reported Outcomes After Prostate Radiation Therapy: Detailed Assessment of Rectal Bleeding.

PURPOSE: The new short Expanded Prostate Cancer Index Composite for Clinical Practice (EPIC-CP) patient-reported health-related quality of life (HRQOL) tool has removed the rectal bleeding question from the previous much longer version, EPIC-26. Herein, we assess the impact of losing the dedicated rectal bleeding question in 2 independent prospective multicenter cohorts. METHODS AND MATERIALS: In a prospective multicenter test cohort (n=865), EPIC-26 patient-reported HRQOL data were collected for 2 years after treatment from patients treated with prostate radiation therapy from 2003 to 2011. A second prospective multicenter cohort (n=442) was used for independent validation. A repeated-effects model was used to predict the change from baseline in bowel summary scores from longer EPIC instruments using the change in EPIC-CP bowel summary scores with and without rectal bleeding scores. RESULTS: Two years after radiation therapy, 91% of patients were free of bleeding, and only 2.6% reported bothersome bleeding problems. Correlations between EPIC-26 and EPIC-CP bowel scores were very high (r2=0.90-0.96) and were statistically improved with the addition of rectal bleeding information (r2=0.94-0.98). Considering all patients, only 0.2% of patients in the test cohort and 0.7% in the validation cohort reported bothersome bleeding and had clinically relevant HRQOL changes missed with EPIC-CP. However, of the 2.6% (n=17) of men with bothersome rectal bleeding in the test cohort, EPIC-CP failed to capture 1 patient (6%) as experiencing meaningful declines in bowel HRQOL. CONCLUSIONS: Modern prostate radiation therapy results in exceptionally low rates of bothersome rectal bleeding, and <1% of patients experience bothersome bleeding and are not captured by EPIC-CP as having meaningful HRQOL declines after radiation therapy. However, in the small subset of patients with bothersome rectal bleeding, the longer EPIC-26 should strongly be considered, given its superior performance in this patient subset.

Development and Validation of Consensus Contouring Guidelines for Adjuvant Radiation Therapy for Bladder Cancer After Radical Cystectomy.

PURPOSE: To develop multi-institutional consensus clinical target volumes (CTVs) and organs at risk (OARs) for male and female bladder cancer patients undergoing adjuvant radiation therapy (RT) in clinical trials. METHODS AND MATERIALS: We convened a multidisciplinary group of bladder cancer specialists from 15 centers and 5 countries. Six radiation oncologists and 7 urologists participated in the development of the initial contours. The group proposed initial language for the CTVs and OARs, and each radiation oncologist contoured them on computed tomography scans of a male and female cystectomy patient with input from ≥1 urologist. On the basis of the initial contouring, the group updated its CTV and OAR descriptions. The cystectomy bed, the area of greatest controversy, was contoured by another 6 radiation oncologists, and the cystectomy bed contouring language was again updated. To determine whether the revised language produced consistent contours, CTVs and OARs were redrawn by 6 additional radiation oncologists. We evaluated their contours for level of agreement using the Landis-Koch interpretation of the κ statistic. RESULTS: The group proposed that patients at elevated risk for local-regional failure with negative margins should be treated to the pelvic nodes alone (internal/external iliac, distal common iliac, obturator, and presacral), whereas patients with positive margins should be treated to the pelvic nodes and cystectomy bed. Proposed OARs included the rectum, bowel space, bone marrow, and urinary diversion. Consensus language describing the CTVs and OARs was developed and externally validated. The revised instructions were found to produce consistent contours. CONCLUSIONS: Consensus descriptions of CTVs and OARs were successfully developed and can be used in clinical trials of adjuvant radiation therapy for bladder cancer.

Patient-reported quality of life after stereotactic body radiotherapy (SBRT), intensity modulated radiotherapy (IMRT), and brachytherapy.

BACKGROUND AND PURPOSE: Stereotactic body radiotherapy (SBRT) is being used for prostate cancer, but concerns persist about toxicity compared to other radiotherapy options. MATERIALS AND METHODS: We conducted a multi-institutional pooled cohort analysis of patient-reported quality of life (QOL) [EPIC-26] before and after intensity-modulated radiotherapy (IMRT), brachytherapy, or SBRT for localized prostate cancer. Data were analyzed by mean domain score, minimal clinically detectable difference (MCD) in domain score, and multivariate analyses to determine factors associated with domain scores at 2-years. RESULTS: Data were analyzed from 803 patients at baseline and 645 at 2-years. Mean declines at 2-years across all patients were -1.9, -4.8, -4.9, and -13.3 points for urinary obstructive, urinary incontinence, bowel, and sexual symptom domains, respectively, corresponding to MCD in 29%, 20%, and 28% of patients. On multivariate analysis (vs. IMRT), brachytherapy had worse urinary irritation at 2-years (-6.8 points, p<0.0001) but no differences in other domains (p>0.15). QOL after SBRT was similar for urinary (p>0.5) and sexual domains (p=0.57), but was associated with better bowel score (+6.7 points, p<0.0002). CONCLUSIONS: QOL 2-years after brachytherapy, IMRT, or SBRT is very good and largely similar, with small differences in urinary and bowel QOL that are likely minimized by modern techniques.

Combining immunotherapy and radiation for prostate cancer.

Radiotherapy has conventionally been viewed as immunosuppressive, which has precluded its use in combination with immunotherapy for prostate and other cancers. However, the relationship between ionizing radiation and immune reactivity is now known to be more complex than was previously thought, and data on the use of radiotherapy and immunotherapy are accumulating. Herein, we review this topic in the light of recently available data in the prostate cancer setting. Recent research has shown no significant lymphopenia in patients undergoing radiotherapy for high-risk adenocarcinoma of the prostate. In addition, emerging evidence suggests that radiotherapy can have immunostimulatory effects, and that tumor cell death, coupled with related changes in antigen availability and inflammatory signals, can affect lymphocyte and dendritic cell activation. Initial studies have focused on combinations of tumor irradiation and immunotherapy, such as the autologous cellular immunotherapy sipuleucel-T and the monoclonal antibody ipilimumab, in metastatic castration-resistant prostate cancer. These combinations appear to have clinical promise, and further investigation of the potentially synergistic combination of radiotherapy and immunotherapy is continuing in clinical trials.

The promise of combining radiation therapy and immunotherapy: morbidity and toxicity.

Radiation therapy and immunotherapy in partnership may have the capability of delivering a therapeutic effect exceeding the sum of its parts. The possible relationship has been demonstrated in murine models and has been extended to a variety of clinical trials. Though the standard notion of whole body radiation therapy is immunosuppressive, there is growing evidence toward the contrary for focal radiation therapy. Furthermore, if immunotherapeutic techniques can retune the immune system against cancerous cells, they should have obvious benefits for advanced treatments moving forward. Herein, we explore the promise in combining radiation therapy and immunotherapy with distinct focus on potential morbidities and toxicities through analysis of completed clinical trials.

Building on sipuleucel-T for immunologic treatment of castration-resistant prostate cancer.

BACKGROUND: Sipuleucel-T is an autologous cellular immunotherapy approved by the US Food and Drug Administration for the treatment of asymptomatic or minimally symptomatic metastatic castration-resistant prostate cancer. Its mechanism of action is based on stimulation of the patient's own immune system to target prostate cancer. Peripheral blood mononuclear cells, including antigen-presenting cells and T cells, are obtained from patients via leukapheresis and treated ex vivo with PA2024, a fusion protein consisting of prostatic acid phosphatase/granulocyte-macrophage colony-stimulating factor antigen. METHODS: Data relating to the potential pharmacodynamic biomarkers associated with sipuleucel-T activity are reviewed, as well as considerations for patient selection and for sequencing sipuleucel-T with other prostate cancer treatments. Possible directions for future development are also discussed, including treatment of less advanced prostate cancer populations, combination treatment, and immune modulation. RESULTS: Data from three randomized, double-blind, placebo-controlled phase III clinical trials of sipuleucel-T in patients with metastatic castration-rresistant prostate cancer have shown improvement in overall survival vs control. Here, we review its developing role in prostate cancer therapy and future directions for development. CONCLUSIONS: There is potential to build on sipuleucel-T to further advance immunotherapy of prostate cancer.

The confluence of stereotactic ablative radiotherapy and tumor immunology.

Stereotactic radiation approaches are gaining more popularity for the treatment of intracranial as well as extracranial tumors in organs such as the liver and lung. Technology, rather than biology, is driving the rapid adoption of stereotactic body radiation therapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), in the clinic due to advances in precise positioning and targeting. Dramatic improvements in tumor control have been demonstrated; however, our knowledge of normal tissue biology response mechanisms to large fraction sizes is lacking. Herein, we will discuss how SABR can induce cellular expression of MHC I, adhesion molecules, costimulatory molecules, heat shock proteins, inflammatory mediators, immunomodulatory cytokines, and death receptors to enhance antitumor immune responses.