Top 10 ASTRO Abstracts

The theme for the 2015 American Society for Radiology Oncology (ASTRO) annual meeting was Technology Meets Patient Care. Hundreds of important abstracts were presented.

Many Cleveland Clinic cancer clinicians and researchers attended and presented at ASTRO’s October 18-21 session. Since then, we’ve discussed and debated which presentations we found most intriguing or that we feel have the greatest potential to change the practice of radiation oncology. We’ve landed on the following as our Top 10 list of the abstracts worth noting from the fall 2015 ASTRO meeting. Do you agree? Let us know your thoughts.

Prostate Cancer
1. NRG Oncology RTOG 0415: A randomized phase III non-inferiority study comparing two fractionation schedules in patients with lowrRisk prostate cancer
W. Robert Lee, MD, MS, MEd, FASTRO
Commentary: The understanding of prostate cancer sensitivity to radiation dose and fractionation has evolved along with radiation technology. Multiple studies, including data from Cleveland Clinic, have shown the ability to safely and effectively apply short courses of highly conformal radiation therapy. This study represents the largest prospective randomized study of moderate hypofractionation for prostate cancer, and when combined with other published experiences, will likely provide more options for patients with low-risk prostate cancer.

Prostate Cancer
2. NRG Oncology/RTOG 9601: A phase III trial in prostate cancer: Anti-androgen therapy (AAT) with bicalutamide during and after radiation therapy (RT) in patients following radical prostatectomy (RP) with pT2-3pN0 disease and an elevated PSA
William U. Shipley, MD, FASTRO
Commentary: It is logical that patients with more locally aggressive prostate cancer will be at higher risk for microscopic distant metastatic disease prostate cancer. This study showed statistically significant benefits in distant metastatic disease control, overall and prostate cancer specific-survival with the addition of bicalutamide in the post-prostatectomy setting. Not unexpectedly, there was an increase in the rate of gynecomastia (70 percent vs 11 percent with placebo). Future directions may incorporate the use of novel antiandrogen treatments and results from RTOG 0534, which tested luteinizing hormone-releasing hormone (LHRH) agonist and treatment of pelvic lymph nodes. This study will also build on our knowledge of adjuvant systemic therapy learned in RTOG 0621, a phase II study of radiation, androgen deprivation therapy and docetaxel for high-risk patients treated with prostatectomy.

Breast Cancer
3. Accelerated partial breast irradiation using sole interstitial multicatheter brachytherapy versus whole breast irradiation for early breast cancer: 5-year results of a randomised phase III trial – part I: Local control and survival results
Vratislav Strnad, MD, PhD
Commentary: Recent clinical trials such as this are examining the feasibility, safety and efficacy of partial versus whole-breast radiation therapy. Accelerated partial breast irradiation (APBI) is based on the principle that the area of highest risk for recurrence after a partial mastectomy for women with early-stage breast cancer is the region around the primary tumor bed. Based on this and other studies, partial breast radiation can be an option for selected low-risk patients as this study showed no difference in rates of local recurrence. Although partial breast irradiation techniques are increasingly being used, this should be considered only in a selected low-risk population of patients with breast cancer, and preferably be studied prospectively.

Bone Pain
4. Dexamethasone versus placebo in the prophylaxis of radiation-induced pain flare following palliative radiation therapy for bone metastases: a double-blind randomized, controlled, superiority trial
Edward Chow, MBBS, PhD
Commentary: Radiotherapy remains a standard treatment for cancer-induced bone pain. However pain flare from palliative radiation therapy occurs in approximately one-third of patients. For patients who develop pain flares, treatment options include increasing a patient’s analgesic medication and/or a short course of steroids. This study showed that dexamethasone can reduce the incidence of pain flare and improve a patient’s quality of life. It should be noted that the reduction in pain flare with dexamethasone was approximately 10 percent. To further improve management, studies are needed to identify patients most at risk for pain flare, and to further elucidate the mechanisms of cancer and treatment-related bone pain.

Lung Cancer
5. Primary study endpoint analysis for NRG Oncology/RTOG 0813 trial of stereotactic body radiotherapy (SBRT) for centrally located non-small cell lung cancer (NSCLC)
Andrea Bezjak, MD, FRCPC, MSc
Commentary: RTOG 0813 was a prospective phase I/II trial that studied the maximal tolerated dose (MTD) and efficacy of SBRT for medically inoperable early stage NSCLC patients with “centrally” located tumors, i.e., within 2 cm of the tracheobronchial tree or mediastinal structures. Treatment of “central” tumors has been of particular interest because of prospective studies from Indiana University that suggested excessive rates of high-grade toxicities with a schedule of 60 Gy in three fractions when delivered to this area (compared to other schedules that suggested no increased risk). RTOG 0813 involved a stepwise incremental dose increase from 50 Gy to 60 Gy, all in five fractions. 60 Gy in five fractions was associated with a 7.2 percent rate of dose-limiting toxicity. Given this, the efficacy (i.e., local control) data are awaited in order to determine if this dose level is appropriate for further study or clinical use.

Prostate Cancer
6. Contemporary update of a multi-institutional predictive nomogram for salvage radiation therapy after prostatectomy
Rahul Tendulkar, MD
Commentary: This retrospective study is an update of the largest reported series in the literature regarding salvage radiation therapy after a prostatectomy. Important additions to the original Stephenson paper include the inclusion of patients treated with “early salvage” radiation therapy at PSA <0.2 ng/ml, which was associated with improved rates of biochemical control and distant metastases compared to utilizing salvage radiation at a higher PSA. A nomogram was created to better predict individual patient outcomes of PSA control and distant metastases in the modern era.

Lung Cancer
7. NRG Oncology/RTOG 0937: Randomized phase II study comparing prophylactic cranial irradiation (PCI) alone to PCI and consolidative extra-cranial irradiation for extensive disease small cell lung cancer (ED-SCLC)
Elizabeth M. Gore, MD
Commentary: Treatment for patients with extensive disease small cell lung cancer (ED-SCLC) remains a significant challenge due to the aggressive nature of this disease. Although disease progression was influence by extracranial irradiation, overall survival was not impacted. Continued research is needed in this patient population and participation should be encouraged for studies available at various institutions.

Prostate Cancer
8. Hypofractionated versus conventionally fractionated radiotherapy for prostate cancer: 5-year oncologic outcomes of the Dutch randomized phase 3 HYPRO trial
Luca Incrocci, MD, PhD
Commentary: Varying degrees of hypofractionation have been applied to patients with prostate cancer. Assuming patients were well-balanced in this study, this may become a hypofractionation option for the treatment of properly selected prostate cancer patients. Data from this and other hypofractionation studies such as RTOG 0928 will be scrutinized in the near future.

Head and Neck Cancer
9. A Prospective phase II trial of deintensified chemoradiation therapy for low-risk HPV associated oropharyngeal squamous cell carcinoma
Bhisham S. Chera, MD
Commentary: As evidenced from RTOG and institutional data, patients with HPV-associated head and neck cancer in the setting of minimal or no tobacco abuse history have a more favorable prognosis. Treatment with chemoradiation may result in significant acute and late morbidity. Based on data from this and other studies, future randomized studies will test treatment de-intensification for this group of favorable-risk patients.

Prostate Cancer
10. Patient reported outcomes in NRG Oncology/RTOG 0938, a randomised phase II study evaluating two ultrahypofractionated regimens (UHR) for prostate cancer
Himanshu Lukka, MB, ChB, MRCP, FRCR, FRCPC
Commentary: The phase II RTOG 0938 closed to accrual in February 2015 and tested five versus 12 daily fractions of radiation therapy. This study reports no significant difference in terms of acute or late toxicity between treatment arms. Longer follow-up and a larger study will be needed to provide robust data regarding safety and efficacy of this newer treatment.