Instructions: Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
Input: To investigate the effect of the percentage of free prostate-specific antigen (%fPSA) on future prostate cancer risk.', 'We examined serum total PSA (tPSA) and %fPSA annually in a prostate cancer-screening cohort between July 2001 and June 2011. Men with tPSA >4.0 ng/mL or tPSA of 2.0-4.0 ng/mL with %fPSA 12% were screened as positive and were recommended to undergo a biopsy. The study population consisted of 6368 men, aged 40-79 years, who had tPSA 4.0 ng/mL at initial screening and who subsequently underwent 1 or more screenings. We calculated the cumulative risk and hazard ratio of prostate cancer stratified by the initial %fPSA groups as quartiles of prostate cancer patients.', 'During a median follow-up of 36 months, 119 men were diagnosed with prostate cancer. The lowest quartile of %fPSA (<13.3%) was associated with a 21.2-fold higher risk of having prostate cancer compared with the highest quartile (>22.2%). For the subset with an initial tPSA 1.0 ng/mL, all men diagnosed with cancer had an initial %fPSA 33.3% (median). For the subset with tPSA >1.0 ng/mL, men with %fPSA 23.0% (median) had significantly higher risk for cancer than those with %fPSA >23.0% (P <.0001). Of the 114 men with prostate cancer in whom pathologic findings were available, 79 (69.3%) had a Gleason score 3 + 4 = 7.
Output:
Is low percentage of free prostate-specific antigen ( PSA ) a strong predictor of later detection of prostate cancer among Japanese men with serum levels of total PSA of 4.0 ng/mL or less?