Assessing prostate-specific antigen levels for 3 months after radical prostatectomy may help minimize overtreatment, according to findings in JAMA Oncology.

Men with a persistent prostate-specific antigen (PSA) level after radical prostatectomy (RP) for prostate cancer (PC) who had a pre–RP PSA level greater than 20 ng/mL had a reduced risk of all-cause and PC-specific mortality compared with patients with lower pre–RP PSA levels. The unexpected finding was reported in JAMA Oncology.

“To find a reason for the more favorable prognosis in patients with a higher pre-RP PSA level, we hypothesized that a higher proportion of patients with a pre-RP PSA greater than 20 ng/mL compared with 20 ng/mL or less assessed for a persistent PSA at the conventional 1.5-month to 2.0-month time point post-RP could have reached an undetectable PSA level if further PSA assessment was performed before initiating post-RP therapy for a presumed persistent PSA,” wrote corresponding author Anthony V. D’Amico, MD, PhD, and colleagues.

The study included 43,298 patients with PC treated with RP. Among them, 30,461 made up the discovery cohort, and 12,837 made up the validation cohort.

Compared with patients with undetectable PSA in the discovery cohort, patients with a pre–RP PSA level greater than 20 ng/mL, versus 20 ng/mL or less, had adjusted hazard ratios of 0.69 for all-cause mortality and 0.41 for PC-specific mortality, according to the study. The association of reduced risk with a higher pre–RP PSA level was confirmed for PC-specific mortality in the validation cohort.

Supporting the researchers’ hypothesis as to the cause of reduced mortality in men with higher pre–RP PSA levels and persistent post–RP PSA, the study also identified care differences. Post-RP radiation therapy and androgen deprivation therapy were more frequent, and were initiated more quickly, for patients with a pre–RP PSA greater than 20 ng/mL versus those with a pre–RP PSA of 20 ng/mL or less.

“These treatment times were shorter than the times to an undetectable PSA in observed patients (median [IQR] of 2.96 [1.84-3.29] months vs 3.37 [2.35-4.09] months, respectively),” researchers pointed out.

The study also found that an increasing post-RP persistent PSA level was associated with an increased risk of all-cause and PC-specific mortality.

“In conclusion, PSA level assessed for at least 3 months after RP may minimize overtreatment,” researchers advised, “and in this study, a higher persistent PSA level was associated with a worse prognosis.”