Re: Fasting times in serum PSA assay

clinical effect. The authors recommend that the optimal time to obtain an accurate PSA level is fasting for 7–9 h, which avoids the increased PSA levels observed with fasting extremes as well as possible diurnal rhythm variations that may exist in shorter fasting times. This is an interesting study with meaningful results. The authors have addressed obvious limitations such as potential recall errors by the patients and the nonrandomness of the cohorts. Based on these findings, it seems that fasting time may not be a concern for prostate cancer screening as the small variations (∼1%) is unlikely to change the PSA value over or under the threshold for most patients. However, for patients monitored for disease recurrence such as those after surgery or radiation for high risk prostate cancer, or for patients with advanced prostate cancer treated with conventional hormonal therapy or the newer agents, testing PSA under similar fasting conditions (7–9 h) may be advisable for consistent testing, since the trend in serial PSA tests are critical for clinical decision-making.