ASTRO 2018: Response to Radiotherapy in African American Men With Prostate Cancer
Posted: Thursday, November 8, 2018
African American men with prostate cancer treated with radiotherapy may have improved outcomes compared with white men with prostate cancer treated with radiotherapy, according to a new report of genetic data from a large prospective registry as well as clinical data from several randomized trials. The investigators concluded that African American men may harbor more radiosensitive tumors than their white counterparts, although further study is warranted. These findings were presented during a plenary session at the 2018 Annual Meeting of the American Society for Radiation Oncology (ASTRO) in San Antonio (Abstract 4).
“When we started this project, we had the commonly held assumption that African American men harbor more aggressive disease that leads to lower survival rates. We were surprised, however, that they appear to be more responsive than Caucasian men to radiation therapy and have improved outcomes following this treatment,” stated lead author Daniel E. Spratt, MD, of the University of Michigan Rogel Cancer Center, Ann Arbor, in an ASTRO press release.
In this two-part study, the team first evaluated tumor samples from 17,003 men (1,953, or 11.5%, African American) with prostate cancer. Tumors with low androgen receptor activity were significantly more likely to develop distant metastases within 10 years, and tumors from African American men were significantly more likely to have low androgen receptor activity. In addition, tumors from African American men were more likely to have indicators of increased sensitivity to radiation therapy.
Next, the team focused on 5,854 patients (19.3% African American) from 4 large NRG Oncology/RTOG randomized prostate cancer trials. In this meta-analysis, African American men treated with radiotherapy had significantly improved outcomes compared with white men, with lower rates of biochemical cancer recurrence and distant metastasis.
“Differences in gene expression between African American and Caucasian patients revealed that African American patients had lower DNA repair and more immunogenic tumors, both of which have been shown to predict better responses to radiation therapy,” Dr. Spratt commented.
