Abstract
PSA measurements are used to assess the risk for prostate cancer. PSA range and PSA kinetics such as PSA velocity have been correlated with in creased cancer detection and assist the clinician in deciding when prostate biopsy should be performed. Our aim is to evaluate the use of a novel, maxi mum likelihood estimation - prostate specific antigen (MLE-PSA) model for predicting the probability of prostate cancer using serial PSA measurements combined with PSA velocity in order to assess whether this reduces the need for prostate biopsy. A total of 1976 Caucasian patients were included. All these patients had at least 6 PSA serial measurements; all underwent trans-rectal biopsy with minimum 12 cores within the past 10 years. A multivariate logistic re gression model was developed using maximum likelihood estimation (MLE) based on the following parameters (age, at least 6 PSA serial measurements, baseline median natural logarithm of the PSA (ln(PSA)) and PSA velocity (ln(PSAV)), baseline process capability standard deviation of ln(PSA) and ln(PSAV), significant special causes of variation in ln(PSA) and ln(PSAV) detected using control chart logic, and the volatility of the ln(PSAV). We then compared prostate cancer probability using MLE-PSA to the results of prostate needle biopsy. The MLE-PSA model with a 50% cut-off probability has a sensitivity of 87%, specificity of 85%, positive predictive value (PPV) of 89%, and negative predictive value (NPV) of 82%. By contrast, a single PSA value with a 4ng/ml threshold has a sensitivity of 59%, specificity of 33%, PPV of 56%, and NPV of 36% using the same population of patients used to generate the MLE-PSA model. Based on serial PSA measurements, the use of the MLE-PSA model significantly (p-value < 0.0001) improves prostate cancer detection and reduces the need for prostate biopsy.
Highlights
According to the American Cancer Society [1] prostate cancer is the second leading cause of death in men after lung cancer and the most diagnosed cancer in men after skin cancer
Schroder et al [13] noted that PSA velocity (PSAV) may not be useful in detecting prostate cancer, disclosing that 985 needle biopsies for men who had a prostate-specific antigen (PSA) value 4.0 to 9.0 ng/ml resulted in a positive predictive value of only 24.5%
Vickers et al [16] noted that calculating PSAV and doubling time proffer inadequate information concerning prostate cancer in untreated patients than PSA values and is of minimal help to the clinician for decision making before treating men with early stage prostate cancer
Summary
According to the American Cancer Society [1] prostate cancer is the second leading cause of death in men after lung cancer and the most diagnosed cancer in men after skin cancer. PSA kinetics which includes PSAV and PSA doubling time has been proposed for the early diagnosis of prostate cancer. Schroder et al [13] noted that PSAV may not be useful in detecting prostate cancer, disclosing that 985 needle biopsies for men who had a PSA value 4.0 to 9.0 ng/ml resulted in a positive predictive value of only 24.5%. Vickers et al [16] noted that calculating PSAV and doubling time proffer inadequate information concerning prostate cancer in untreated patients than PSA values and is of minimal help to the clinician for decision making before treating men with early stage prostate cancer. For example in a study of 12,090 men, Lilja et al [17] concluded that PSA is highly predictive of long-term risk of prostate cancer and that almost 50% of all deaths could be prevented by monitoring the PSA levels of those with the highest PSA levels at age 44-50
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
