Researchers have identified a viable new treatment option for individuals whose PSA levels rise after radical prostatectomy.
Numerous men who undergo radical prostatectomy for prostate cancer live their entire lives without a recurrence of the disease. Twenty to forty per cent of them will suffer an increase in prostate-specific antigen (PSA) values within ten years of surgery. If the prostate has been removed, PSA levels in the blood should be undetectable, indicating that cancer may have returned. This is known as a biochemical relapse, and it is often treated with radiation to the prostate bed, where the prostate resided prior to its removal. This type of treatment, known as pelvic bed radiation therapy or PBRT, is frequently successful in reducing PSA levels to zero for years.
Now, a comprehensive study demonstrates that PBRT is even more beneficial when paired with other therapies. Men who experience a biochemical recurrence following radical prostatectomy may benefit from these findings.
Funded by the National Cancer Institute, almost 300 medical centres in the United States, Canada, and Israel participated in the SPPORT phase 3 clinical trial. Between 2008 and 2015, a total of 1,797 men with post-surgical PSA values between 1 and 2 nanograms per millilitre (ng/mL) were included.
Approximately equal numbers of patients were assigned at random to each of the three groups. Group 1 received PBRT alone, while group 2 received PBRT combined with four to six months of androgen deprivation therapy (ADT). (Also known as hormonal therapy, ADT inhibits testosterone, a hormone or androgen that promotes the development of prostate cancers.) The men in group 3 were treated with PBRT, ADT, and radiation to the pelvic lymph nodes, where prostate cancer generally spreads first. The researchers intended to determine which of these three treatments is the most successful at preventing the advancement of the disease.
The outcomes, side effects, and next steps
According to their findings, more intensive treatments produced greater results. After five years, slightly more than 70 per cent of men in group 1 were still disease-free, compared to 80.3% of men in group 2 and 87.4% of men in group 3. During the follow-up period, 145 men in group 1 acquired further PSA elevations, compared to 104 men in group 2 and 83 men in group 3. Similar tendencies were identified in terms of the number of men who acquired metastases or cancer that develops resistance to hormone therapy as it spreads.
Additionally, the more rigorous treatments produced more short-term side effects, including diarrhoea. After three months, however, disparities in adverse effects between the three groups disappeared.
The authors underlined that a longer follow-up is still necessary to determine whether the addition of ADT and pelvic node radiation to PBRT actually increases survival. In addition, the study did not analyse a more recent therapeutic strategy for biochemical relapse, in which physicians employ advanced imaging techniques to locate extremely small metastases throughout the body, which are then treated directly with radiation.
Dr Marc Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor of the Harvard Health Publishing Annual Report on Prostate Diseases believes it is essential for men to understand that any detectable PSA level after radical prostatectomy is abnormal and warrants further evaluation. "The traditional normal PSA range of 0 to 4 ng/mL does not apply to males whose prostates have been surgically removed," he explains. "Significant evidence of further benefits from combining ADT and pelvic radiation was found during this research. To determine whether this represents a new standard of care for biochemical relapse, additional research is required."