What definitive diagnostic test is indicated for prostate cancer?

The definitive diagnostic test for prostate cancer is a transrectal ultrasound-guided biopsy. This procedure involves using ultrasound to visualize the prostate and guide the physician in obtaining tissue samples. The biopsy is crucial because it allows for histopathological examination of the prostate tissue, which can confirm the presence of cancerous cells.

While the other options can provide useful information, they do not definitively diagnose prostate cancer. The prostate-specific antigen (PSA) test can indicate increased levels associated with prostate cancer, but it is not specific and can yield false positives due to other benign conditions. A digital rectal exam (DRE) can help detect abnormalities in the prostate, but it is limited in sensitivity and cannot confirm cancer without biopsy. A CT scan of the abdomen may be useful for staging or assessing metastatic disease but is not a primary diagnostic tool for prostate cancer itself.

Therefore, the transrectal ultrasound-guided biopsy is essential as it directly obtains tissue samples that can confirm or rule out the diagnosis of prostate cancer, making it the definitive test needed in this scenario.