Establishment of the optimal follow-up schedule after radical prostatectomy
Radical prostatectomy is widely performed as the primary treatment for clinically localized prostate cancer. Monitoring the serum level of prostate specific antigen (PSA) is indispensable for surveillance after radical therapy in order to identify the patients who might need additional treatment for recurrence. Since early salvage therapy for recurrence is known to be advantageous, it is important to detect elevation of PSA without delay. However, unnecessarily intensive PSA follow-up could increase medical expenses and the burden on physicians and patients.
We retrospectively reviewed the clinicopathological data of 1,010 consecutive patients who underwent radical prostatectomy between 1996 and 2008. We excluded patients who received neoadjuvant/adjuvant therapy and those without a nadir PSA level <0.2 ng/mL. The remaining 779 patients were enrolled in this study. Biochemical recurrence (BCR) was defined as elevation of PSA to > 0.2 ng/mL. We focused on the BCR rate and the PSA doubling time (DT) following BCR at various times after radical prostatectomy. The PSA-DT distribution showed a log-normal distribution, and the minimum PSA-DT was defined as a one-sided lower 95% confidence limit.
During the mean follow-up period of 8.8 years, BCR occurred in 179 patients. Kaplan-Meier analysis demonstrated that the BCR rate per year was 6% in the first year after surgery, 6% between 1-2 years, 3% between 2-3 years, 3% between 3-5 years, and 2% at > 5 years postoperatively. The minimum PSA-DT after BCR was 1.6, 2.4, 3.1, 6.1, and 6.4 months, respectively (Figure 1). These minimum PSA-DTs were taken to indicate the optimal follow-up interval during each period after surgery. When a patient has a baseline PSA of 0.1 ng/mL, we should measure PSA at approximately 3-month intervals for the first year, at 4-month intervals between 1-2 years, at 6-month intervals between 2-3 years, and annually thereafter to definitely detect BCR before the PSA exceeds 0.4 ng/mL (Table 1).
The PSA-DT following BCR varied according to the timing after radical prostatectomy. Our data on minimum PSA-DTs after BCR are useful for setting the optimal follow-up schedule that is both necessary and sufficient.