Prostate Cancer - Diagnostics
When a patient complains of symptoms that could be related to a prostate disease further diagnostic work-up is recommended. This includes a digital-rectal examination (DRE), during which the doctor can detect abnormalities of the prostate with his finger and the determination of total PSA level in the blood. If the digital rectal examination is suspicious, a biopsy of the prostate is recommended.
PSA (prostate-specific antigen) is a protein formed in the prostate and discharged into the bloodstream as a result of various diseases of the prostate, for example during an infection, benign growth, or a tumor. The consequence of elevated PSA though, is controversially discussed. If the PSA-level is within a so called grey zone doctors recommend further testing, e.g. retesting, additional parameters, or ultrasound examination, to distinguish between different causes of the PSA elevation. A biopsy is then recommended if there is a clear suspicion of prostate cancer.
An ultrasound examination of the prostate is called transrectal sonography. During this exam, the physician carefully inserts a special ultrasound probe into the rectum in order to examine the prostate more closely. However, ultrasound is not capable of differentiating between non-malignant and malignant lesions. Only a prostate tissue biopsy can determine the presence of tumor cells and thus confirm a suspicion of cancer.
A biopsy is usually taken using local anesthetic on an outpatient basis; an overnight hospital visit is not necessary. An ultrasound performed at the same time allows the physician to guide the biopsy needle exactly. Usually five or more tissue samples are taken from each prostatic lobe. If other examinations already showed additionally suspicious lesions, additional samples are being taken from these areas of the prostate.
If cancer is found, the tumor is classified according to the so called Gleason Scale, which provides information on the aggressiveness of a tumor. If no cancerous tissue has been determined, but the PSA values remain elevated, an additional biopsy should be performed after a certain waiting period. Sometimes an additional magnetic resonance imaging (MRI) of the prostate can be helpful to more precisely localize potential tumorous regions in the prostate gland.
If a suspicion of prostate cancer is confirmed, examinations to find other potential cancerous sites (metastasizes): might be necessary:
- PET/SPECT: Since prostate cancer frequently metastasizes to the bones, a nuclear medical imaging procedure such as PET (Positron Emission Tomography) or SPECT (Single Photon Emission Computed Tomography) is performed. These methods provide the physician with a view into bone metabolism and visualize irregularities characteristic of tumors.
- MRI: MRI is sensitive to detect the exact tumor margins in the pelvis and whether the tumor has already spread into the surrounding lymph nodes.
- CT: Computed tomography in prostate cancer patients is usually requested either for radiation therapy preparation or if a metastatic disease is suspected. To rule out metastatic disease a contrast agent enhanced CT is performed in the majority of cases.