Stereotactic Body Radiotherapy for High-Risk Localized Prostate Cancer
Posted: Wednesday, April 21, 2021
A consortium analysis, conducted by Amar U. Kishan, MD, of the University of California, Los Angeles, and international colleagues, explored the toxicity and efficacy of stereotactic body radiation therapy in high-risk localized prostate cancer. Their findings reported a “favorable” efficacy and toxicity profile for these patients, and additional prospective studies are necessary to determine the optimal dose and target volume in this clinical context. The results of this study were published as a scientific letter in the International Journal of Radiation Oncology • Biology • Physics.
The researchers focused on data from 344 men with high-risk localized prostate cancer treated with stereotactic body radiation therapy who had at least 24 months of follow-up. Age at treatment, clinical T stage, dose per fraction, and the usage of androgen-deprivation therapy (ADT) and nodal radiation therapy were identified for each patient.
The median follow-up was 49.5 months, and 72% of patients received ADT over a median duration of 9 months. For patients receiving stereotactic body radiotherapy, the estimated biochemical recurrence–free survival and distant metastasis–free survival rates at 4 years were 81.7% and 89.1%, respectively. A total of 59 participants experienced biochemical recurrence, and 26 experienced distant metastasis.
A 7 Gy versus 8 Gy per fraction significantly correlated with an increased biochemical recurrence risk (hazard ratio [HR] = 2.15), yet there appeared to be no significant predictors of the time to distant metastasis. Additionally, a 1-year age increase at treatment was also associated with an increased biochemical recurrence risk (HR = 1.04). Among patients receiving ADT, the biochemical recurrence–free survival was significantly higher, but distant metastasis–free survival did not differ.
Acute gastrointestinal and genitourinary toxicities of grade 2 affected 5% and 18% of patients, respectively. There were no grade 3 toxicities. When combined with a dose per fraction of 8 Gy, ADT was associated with higher odds of grade 2 genitourinary toxicity compared with 7 Gy and 7.25 Gy.
Disclosure: For full disclosures of the study authors, visit redjournal.org.
International Journal of Radiation Oncology • Biology • Physics
