A UCLA-led study found treatments that reduce the risk of being diagnosed with a cancer recurrence based on rising prostate-specific antigen (PSA) levels after radiotherapy, commonly referred to as biochemical recurrence, do not necessarily improve a patient’s long-term overall survival.
The team of investigators found that while biochemical recurrence was associated with a higher risk of death, it still did not meet the criteria to be a reliable surrogate endpoint for overall survival. As defined by the FDA, a clinical outcome directly measures whether people in a trial feel or function better or live longer. A surrogate endpoint is a specific, relatively early outcome that reliably predicts for a clinical outcome that occurs in the longer-term.
Biochemical recurrences occur much earlier in the disease course than metastases or survival and could potentially be the ideal surrogate endpoint for prostate cancer. Therefore, the team evaluated whether biochemical recurrence could be a useful surrogate endpoint for death. This has implications for not only designing clinical trials, but also for evaluating the benefit of various forms of treatment intensification and for counseling patients.
The researchers collected and analyzed data from 11 different studies evaluating radiation therapy dose escalation, the use of androgen deprivation therapy and androgen deprivation therapy prolongation to evaluate the potential of biochemical recurrence as a predictor of survival. Overall, 10,741 patients were included in the analysis.
Despite the potential of using biochemical recurrence as a potential marker to predict overall survival in patients with prostate cancer, the results of the study indicates that it should not be the main focus or primary measure in future clinical trials for localized prostate cancer. Instead, metastasis-free survival, which refers to the period without cancer spreading to other parts of the body, is a more suitable endpoint for future trials involving radiation therapy in localized prostate cancer cases.