by Dr. Stelios Dimitriou
Prostate cancer is the most common cancer and the second leading cause of cancer death among men. Prostate cancer is predominantly a disease of the elder men. Statistically, there are 5500 new cases of the cancer each year in Greece, while in Cyprus there are 460 respectively. The median age at diagnosis is 66 years.
Diagnosis for prostate cancer
Findings that could be associated with underlying prostate cancer are:
A) High Prostate-Specific Antigen (PSA) levels (>4 ng/dl)
B) Abnormal findings (bumps or hard areas of the prostate) during finger examination or Digital Rectal Examination (DRE). Prostate cancer most often develops in the peripheral zone (70%), which is adjacent to the rectum, which explains the usefulness of the DRE in mass screening tests. The remaining cases of prostate cancer (30%) are located in its transitional and central zone.
Patients with prostate cancer may experience trouble urinating, haematuria, pain in the lower back and dull pain in the lower pelvic area due to metastasis to bones.
Prostate cancer may spread to nearby organs (mainly bladder and seminal vesicles, and on rare occasions, urethral and rectum), or to lymph nodes (mainly of the lower abdomen and on rare occasions adjacent to the aorta or the inguinal). Furthermore, distant metastases through the bloodstream can occur, mainly in the bones (90%), lungs (45%), liver (25%), pleura (20%) and adrenal glands (15%).
Medical Imaging
Ultrasound
Transrectal ultrasonography (TRUS) with the use of a special transducer through the rectum, is often performed to detect any suspicious lesions in the prostate gland and to guide prostate biopsy, usually after high PSA levels and / or suspicious findings on finger examination.
Furthermore, TRUS is considered the method of choice for implanting brachytherapy particles for the treatment of confirmed prostate cancer.
MRI
MRI’s initial use was for the local staging of confirmed prostate cancers and for the assessment of any extracapsular (extraprostatic) spread of the disease, that is, the spread of the cancer beyond the fibromuscular pseudocapsule of the prostate, a finding that is obviously associated with a poorer prognosis.
In recent years, however, its role in prostate cancer diagnosis has increased significantly, as it is possible to accurately detect suspected lesions in cases where PSA levels remain significantly high, but repeated, transrectal biopsies give negative results. At the same time, it can be used as a guide for targeted biopsy of lesions suspected of being cancer based on imaging. Furthermore, MRI is used for regular follow-up of patients diagnosed with low-grade malignancy, late-onset cancer confined to the prostate, and for follow-up of patients who underwent radical prostatectomy), however, with increase in PSA levels.
The diagnostic tool of today for prostate cancer is the multi-parametric magnetic resonance imaging (mpMRI) which includes high-resolution T2-weighted (T2W) images to depict prostate anatomy, and two functional MRI techniques, including diffusion-weighted imaging (DWI) to display cell density, and dynamic contrast-enhanced MRI (DCE-MRI) that shows vascularity, after intravenous administration of paramagnetic-contrast agent. It is worth noting that mpMRI’s potential increases significantly when performed on high field MRI scanners, such as the state-of-the-art 3T MRI system MAGNETOM Lumina by Siemens operating at the ALPHA EVRESIS Diagnostic Center, member of the BIOIATRIKI Healthcare Group in Cyprus.
Prostate’s lesions evaluation is based on PI-RADS (Prostate Imaging-Reporting and Data System); each lesion is assigned a score from 1 to 5 indicating the likelihood of clinically significant cancer. Lesions of PI-RADS 1 and 2 have a very low and low respectively probability of being associated with clinically significant prostate cancer, while lesions of PI-RADS 4 and 5 have a high and very high respectively probability of being associated with clinically significant prostate cancer. Lesions of PI-RADS 3 are considered of intermediate suspicion for clinically significant prostate cancer and their treatment approach varies. Clinically significant prostate cancer is defined, histologically, as Gleason score of >7 and/or tumor >0.5 ml and/or cancer metastasis beyond the prostate.
In recent years, fusion guided prostate biopsy, which combines magnetic resonance imaging (MRI) with ultrasound via a special GPS system, is a highly effective method for targeted biopsy of the prostate. Therefore, biopsies are performed with greater accuracy, even in lesions that are distinguishable only on MRI.
Computed Tomography (CT) Scan
CT is not indicated for the local staging of prostate cancer. However, it is used to detect distant metastases in the lungs, bones or solid organs of the abdomen (especially the liver). Additionally, based on the treatment approach, CT aids to radiotherapy planning. In advanced cases, CT scans are the test of choice for swollen lymph nodes in pelvis or near the aorta, for hydronephrosis (i.e., dilation of the ureters and / or pelvicaliceal systems of the kidneys), or for osteoblastic-sclerotic metastases.
Nuclear medicine
Bone scan is commonly used to detect bone metastases, while PET-CT can be used to diagnose, stage, or restage prostate cancer and detect suspected relapses in patients who have undergone treatment, however, their PSA levels are high once more.
To sum up, mpMRI now plays a prime role and is widely used in the diagnosis and imaging of prostate cancer. In other words, we can accurately identify lesions that are considered suspicious for cancer, thus, avoid accidental biopsies. Furthermore, the combination of mpMRI and fusion imaging is an important development, as biopsies are performed with greater accuracy and safety, resulting to diagnosis of up to 30% more cases with clinically significant prostate cancer.
*MD, EDiR Radiologist Alpha Evresis Diagnostic Center, BIOIATRIKI Healthcare Group
