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Diagnosis of Prostate Cancer

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Clinical manifestations.

Blood analysis. Prostate-specific antigen (PSA) is a substance produced by the prostate that can be detected in a blood test. Men usually have low levels of PSA in the blood, a high level may be a sign of cancer.

Rectal exam. Rectal examination is a test performed by the doctor to feel the end of the digestive tube that allows you to explore the rectum and prostate.

Prostate biopsy. This samples the prostate to confirm the anatomopathological diagnosis.

Biochemical diagnosis

PSA is a protein in the kallikrein family produced by prostate tubules and acins, which are responsible for liquefying the seminal fluid.

PSA levels may be altered by other prostate diseases such as benign prostatic hyperplasia. Traditionally, values greater than or equal to 4 ng/ml have been considered normal. Higher PSA levels increase the chance of having a prostate tumour. The positive predictive value of PSA at levels between 4-10 ng/ml is 20-30%, and 42-71.4% for levels above 10 ng/ml.

Population-level screening is performed for patients who are at increased risk of prostate cancer:

Men aged from 50-70.
Men over 45 years with a relative who has prostate cancer.
Men with a PSA greater than 1 ng/ml when they are in their 40s.
Men with a PSA greater than 2ng/ml in their 60s.

Prostate biopsy

A prostate biopsy is usually performed when PSA levels are elevated or a rectal exam raises suspicions. Even if PSA levels are normal, it is essential to diagnose a prostate tumour.

Transrectal and transperineal biopsy. A biopsy can be performed via two different routes, the transrectal route and the transperineal route. The most common is the transrectal route, which can be performed under local anaesthesia or sedation. Transperineal biopsies are performed in the operating room while the patient is sedated. The biopsies are guided by transrectal ultrasound and samples are usually taken systematically from the peripheral area of the prostate.

Guided biopsy. Magnetic Resonance Imaging (MRI) allows the doctor to view the affected areas and make systematic, guided biopsies of areas of the prostate that look suspicious.

Study of the extent / Staging

The image tests in prostate cancer play a key role in both diagnosis and the indication for patient treatment and follow-up.

When there is a clinical suspicion that a patient has prostate cancer, Magnetic Resonance Imaging (MRI) of the prostate is recommended. This is a multiparametric imaging test with intravenous contrast. The MRI makes it possible to observe the presence of a lesion and direct the biopsy necessary to confirm its presence. If there is a cancer, an MRI allows us to assess its location and to know whether it is found only in the prostate or extends beyond, as well as the presence of the disease outside the prostate.

It is important to discover the extent of the disease to select the most appropriate treatment. When the disease may be dispersed at a distance, a computed tomography (CT) scan and a bone scan are performed. CT uses ionising radiation, usually with intravenous contrast, and studies the rest of the abdomen and chest. The bone scan uses a radioactive tracer that attaches to the bones and allows the entire skeleton to be studied.

After treatment, patients are monitored with medical visits, analysis with tumour markers, and follow-up with imaging tests (including MRI) to assess local relapse at the prostate and pelvis level, and a CT scan and bone scan for the rest of the body.

Occasionally, a PET/CT (positron emission tomography) is necessary, both at the time of diagnosis to assess the extent of the disease and when relapse is suspected. A PET/CT scan uses a radioactive tracer, ¹⁸F choline, which shows the regions where prostate disease is active, even though these may be small.