The prostate: function and anatomy
The prostate is a walnut-sized gland that is located inside a man’s body between his bladder and rectum. The prostate surrounds the urethra, the passage in the penis through which urine and semen pass. The prostate fulfills a first function in urination by the presence of sphincters upstream and downstream. It has a sexual function as well, as it is responsible for the preparation of semen and ejaculation. That is why changes in a man’s urinary or sexual function might indicate prostate cancer.
There are three zones within a normal prostate: the posterior peripheral zone and two anterior symmetric lobes that make up the adenoma. The latter tends to grow with age (benign hypertrophy). Sometimes this can cause problems that are common in older men and not always symptoms or signs of cancer.
What is prostate cancer?
Prostate cancer occurs when abnormal cells develop in the prostate. These abnormal cells can continue to multiply in an uncontrolled way and sometimes spread outside the prostate into nearby or distant parts of the body.
Despite being a serious disease, most of the cases are in an early-stage when detected or they grow slowly. This means they have a low risk of spreading and may not even need any immediate treatment or surgery, what allows to promote and maintain a high level of quality of life, and prevents the patient from the chances to suffer from adverse events such as sexual, urinary, and bowel dysfunction after pursuing a sometimes not necessary aggressive treatment.
For this reason, it is important to focus on reaching a precise diagnosis of the cancer case, which let doctors identify where and how the lesion is and its stage and consequently to bring adapted answers to every patient.
How is prostate cancer detected and diagnosed?
Most prostate cancers are first found during screening, as in early stage do not develop any symptom. However, more advanced cancers may cause some urinary or sexual problem that can reveal the disease. If cancer is suspected, some tests will be needed, as well as a final biopsy that will eventually confirm if there is a cancer or not.
Prostate cancer screening is now carried out in two ways: by a Digital Rectal Exam (DRE) and by a PSA blood test.
PSA blood test
This test measures the amount of Prostate Specific Antigen in the blood. PSA is a protein produced by cells in the prostate. A man with prostate cancer often present elevated levels of PSA. However, some men who have prostate cancer have a low PSA level. And PSA levels can also be raised by several other medical conditions not related to cancer.
Digital Rectal Exam (DRE)
During a Digital Rectal Exam, the physician inserts a gloved, lubricated finger into the rectum and examines the prostate for any irregularities in size, shape, and texture that might be a sign of cancer.
MRI before biopsy in diagnosis of prostate cancer
For 10 years, Magnetic Resonance Imaging (MRI) has progressed and showed high sensitivity and specificity for prostate cancer. This technique requires the radiologist’s expertise, who works together with the urologist and the pathologist to locate and define the patient’s disease.
The introduction of the MRI in prostate cancer management has significantly improved the sensitivity and specificity of diagnostic tests for high-risk lesions. Multiparametric MRI is read by an expert radiologist, who will then identify and contour the lesions and assign them a score from 1 to 5, known as PI-RADS score.
Since MRI cannot detect and characterize 100% of lesions or assess the exact tissue extension, biopsy remains the only complementary method that can confirm the diagnosis of prostate cancer. However, when MRI reveals high negative predictive value, an expert examination concluding the absence of lesion may lead to postpone a biopsy.