Prostate Cancer Biochemical Recurrence After External Beam Radiation Therapy

By Patrick Daly - Last Updated: December 2, 2022

In a study presented at the 23rd Annual Meeting of the Society of Urologic Oncology, researchers described long-term rates of biochemical recurrence in patients with prostate cancer treated with primary external beam radiation therapy (EBRT). According to first author and presenter, Domenique Escobar, rates of recurrence were “fairly high,” but the rate of salvage therapies was relatively low.

The analysis enrolled 1035 men with clinically localized prostate cancer treated with EBRT from the Cancer of the Prostate Strategic Urologic Research Endeavor registry. Participants’ cancer risk was evaluated using National Comprehensive Cancer Network (NCCN) criteria, and researchers used Cox models to determine associations between variables of interest and recurrence.

Prostate Cancer Recurrence After ERBT Often Not Salvaged

At time of diagnosis, the cohort had a mean age of 70 ± 6.82 years, median prostate-specific antigen (PSA) of 7.6, and a mean number of 5 follow-up PSA tests. According to the report, the 5- and 10-year rates of biochemical recurrence were 23.6% and 48.9%, respectively. Prostate cancer-specific mortality was 3% at 5 years and 6.9% at 10 years.

Additionally, 10-year recurrence rates were highly correlated with NCCN high-, intermediate-, and low-risk classifications (67.4%, 48.0%, and 34.0%, respectively). NCCN high-risk patients had significantly greater risk than low-risk patients (hazard ratio [HR], 3.7; 95% CI, 2.1-6.6).

Rates for undergoing salvage therapy—most commonly androgen deprivation therapy (ADT)—were 16.5% and 19.8% at 5 and 10 years, respectively. These rates were significantly associated with NCCN high risk compared with low risk (HR, 4.1; 95% CI, 2.4-6.9), the researchers added, as well as concurrent ADT (HR, 1.73; 95% CI, 1.178-2.55).

The investigators acknowledged the strength of their analysis was limited by incomplete data on radiation dose and field size; however, it was increased by the study’s large sample size and long follow-up duration. The authors also proposed that the largely community setting-based data could improve the generalizability of their findings.

Ultimately, the study’s results supported the efficacy of the NCCN recurrence criteria after EBRT for prostate cancer, and the authors further suggested that “not all patients who recur need, are offered, or want treatment.”