Measuring PSA level between treatments can predict likelihood of recurrence

This paper investigates measurement of the levels of the protein prostate-specific-antigen (PSA) as a predictor of cancer returning when the patient is treated with neoadjuvant androgen deprivation therapy and radiotherapy.

Prostate cancer patients have been shown to have higher rates of biochemical relapse-free survival (levels of PSA do not increase, indicating that cancer has not returned) when they receive neoadjuvant androgen deprivation therapy (ADT) followed by radiotherapy. Neoadjuvant ADT is a treatment given prior to the main treatment (in this case radiotherapy) to reduce the androgen (male sex) hormones. The theory is that these treatments prevent testosterone (male hormone) from keeping the cancer cells alive and then turn on the immune system against the cancer cells.

Because of the unique relationship between the two treatments, it has been suggested that PSA levels following ADT may predict the likelihood of survival without biochemical relapse following radiation therapy. A level of 0.5ng/mL or less is associated with a better chance of biochemical relapse-free survival.

The authors aimed to confirm the predictive abilities of PSA levels measured after ADT but before radiation therapy. A total of 105 patients with “intermediate” (68%) or “high-risk” (32%) prostate cancer were evaluated. All patients had PSA data available and were treated with neoadjuvant ADT followed by external beam radiotherapy (uses a high-energy x-ray machine to direct radiation to the tumor). Following radiotherapy treatment all patients were monitored for PSA measurement every 3-4 months for the first 2 years, and every 6 months after.

After an average of 5.4 years 90.9% of patients who had a PSA level of <0.5ng/mL after ADT but before radiotherapy had no sign of biochemical relapse, compared to 68.8% of those who had a PSA of >0.5ng/mL. Having a PSA of >0.5ng/mL between treatments was associated with greater than twice the risk of biochemical recurrence (rising levels of PSA following treatment).

In conclusion, the study indicated that patients with “intermediate” or “high risk” prostate cancer treated with neoadjuvant ADT therapy who achieve a PSA level of <0.5ng/mL prior to radiotherapy treatment have a high chance of at least 5 years without relapse.

The study evaluated patient records (retrospective design), whereas ongoing collection and analysis of patient data is generally associated with a greater strength of results (prospective design).

If considering neoadjuvant ADT before radiotherapy, speak to your doctor about measuring your PSA levels between treatments.