OBJECTIVES

Serum prostate specific antigen and digital rectal examination are the tests used as screening tests to detect prostate cancer. However, only approximately 30% of men with suspicion of cancer have it confirmed on prostate biopsy, and not all of these need treatment. Detection of circulating tumor cells in localized prostate cancer has given variable results, but it could be a useful complementary screening tool to detect prostate cancer in men with abnormal screening tests before the evaluation with prostate biopsy. This may be more so in subsequent biopsies where serum PSA has a decreased diagnostic yield. To evaluate the diagnostic yield of the detection of CPCs as a complementary PC screening test in a population fulfilling criteria for an initial, second and third prostate biopsy for suspicion of PC.

METHODS

A prospective screening study of consecutive patients aged 45-80 years presenting to the urologist for PC screening. Inclusion criteria were PSA >4.0 ng/ml, PSA velocity >0.35 ng/ml/year and/or DRE suspicious for cancer. Patients fulfilling inclusion criteria had blood taken for CPC detection and then underwent 12-core transrectal prostate biopsy. Double immune-his-tochemical staining with anti-PSA and anti-P504S was used to detect CPCs. Both cytologist and pathologist were blinded to the results of the biopsy, CPC results and clinical details. The diagnostic yield of the presence or absence of CPC was evaluated; the prostate biopsy was classified as cancer or no-cancer.

RESULTS

282 men participated, 83 undergoing of these undergoing a second and 38 a third biopsy, with a mean age of 66.2 ± 8.9 years and a median serum PSA of 5.10 ng/ml, 5.45 ng/ml and 6.45 ng/ml for first, second and third biopsies. Cancer was detected in 33,6%, 10.8% and 29.0% of first, second and third biopsies respectively, CPCs were detected in 36.9%, 21.7% and 36.8% of the patients. Sensibility, specificity and negative predictive value were 86% ,91% and 94% for the first biopsy, 89%, 87% and 99% for the second and 100% , 89% and 100% for third biopsy respectively. All the CPC determinations were interpretable. There were 11 false negative cases, all with small low grade tumors. Of the 29 men with a false positive CPC, 8/10 had cancer detected in the subsequent biopsy.

CONCLUSIONS

The use of CPC detection could be useful as a complementary prostate cancer screening test, especially for excluding cancer, and including patients with indications for repeat biopsies. Men with a false positive CPC detection had a high risk of detecting cancer in the succeeding biopsy.