With cancer affecting 1 in 7 men in South Africa (SA) during their lifetime prostate cancer (PCa) is the no. 1 cancer that affects SA men, It is estimated that 1 in 18 SA men will develop prostate cancer according to the National Cancer Registry of South Africa. (NCR-SA, 2014). Prostatic adenocarcinoma (typically called “prostate cancer” or “prostate carcinoma”), a malignancy of prostate gland epithelial cells, accounts for all but a tiny fraction of prostatic malignancies. (NCR-SA, 2014) In the passage below prostate gland anatomy, common masses found in the prostate gland, modalities used to diagnose prostate cancer, role, advantages and limitations of each modality will be discussed.
2. The anatomy and physiology of the prostate
The prostate is a single, doughnut-shaped gland about the size of a golf ball. It measures about 4 cm from side to side, about 3 cm (1.2 in.) from top to bottom, and about 2 cm. Prostate is a pelvic secretory organ located under the urinary bladder and in front of the rectum, and secretes a milky, slightly acidic fluid (pH about6.5) that contains several substances. It is combined by glandular and non-glandular composition encircled by one same container. It also consists of contractile organ fibrous tissue, which it is divided into about 50 tubule-alveolar glands, at the lateral and posterior segment of the urethra, which drain to 20–30 small prostatic ductules opening in the prostate, or close to the posterior wall of the prostatic urethra.
3. The common masses found in the prostate
Benign enlargement owes to glandular hyperplasia, mainly in the central area. On the other hand, prostate cancer usually develops in the posterior and peripheral parts. Some prostatic cancers are palpable because of the employment of DRE and are recognizable because they are much firmer than normal prostate.
According to the masses are separated as the following Small-cell Neuroendocrine Carcinoma, Basal Cell/Adenoid Cystic Carcinoma and Primary will be, Primary Squamous Cell Carcinoma, Primary Urothelial Carcinoma and Primary Sarcomatoid Carcinoma
Nuclear changes, these changes are normally in areas of inflammation,basal cell hyperplasia, atrophy, or Paneth cell-like change. Perineural invasion, includes the presence of glands in a perineural location used to be considered as a diagnostic trademark of malignancy. Circumferential growth or intraneural invasion should be regarded as pathognomonic of cancer. Cytoplasmic features in malignancy vary from clear amphophilic to eosinophilic, they are very useful features in differentiation between benign and atypical/cancerous glands. And collagenous micronodules are another recently described histological observation in Prostate cancer, these nodular can be seen microscopically.
Prostatic crystalloids are intraluminal, eosinophilic and refractile structures of varying size and shape, which are closely associated with prostate cancer.
Diagnostic criteria for benign is prostatic intraepithelial neoplasia (PIN), it is characterized by unrepresentative prostatic epithelial cells that contain some of the molecular changes found in prostatic carcinoma. Massive nodular hyperplasia of the prostate, the middle part of the gland protrudes into the bladder. Benign prostatic hyperplasia (BPH), it is the condition causing nodular hyperplasia of the prostate gland and the fibro-muscular supporting tissue around the gland. (
4. Imaging modalities to diagnose prostate.
The prostate gland diseases surveillance is traditionally performed by ultrasound, initially with transabdominal transducers and later superseded by transrectal (TRUS) transducers (Hegde et al., 2013: 1036)
The following can be used to detect and stage Pca TRUS (can be use with or without MRI), CT (can be used with or without MRI), MRI using SPECT and Bone scan 99Tc- MDP bone scan.(Kelloff et al., 2009; Kim et al., 2010)
Primarily two main modalities that are recently used to diagnose prostate cancer are ultrasound and Magnetic resonance, these modalities have been improved to transrectal ultrasound (TRUS) and multiparametric mpMRI approach. (Heidenreich et al., 2011)
The is a lot of advancement done in prostate MR imaging that is accepted and now is spreading worldwide. The MRI examination in general is performed as a combination of T1 and T2 Weighted imaging, DWI, and dynamic contrast-enhanced DCE imaging (in coronal, sagittal, and axial planes). The article further argues that MRI with either a 1.5- or 3.0-T magnet and with or without an endorectal coil is now the favored and advisable approach to all men presenting with signs of prostate cancer. (Hegde et al., 2013: 164; Penzkofer & Tempany-Afdhal, 2014: 4)
(PET) is still evolving but is likely to be most important in determining the early spread of disease in patients with aggressive tumors and for monitoring response to therapy in more advanced patients. (Schöder & Larson, 2004: 275)
5. The role of each modality, advantages, and limitations.
5.1. Role of each
The transrectal ultrasound (TRUS) biopsy procedure is highly user-dependent, it is able to distinguish whether a lesion is solid, cystic, or vascular. (Birs et al., 2016: 8)
According to (Schöder & Larson, 2004) Transrectal ultrasound (TRUS) is the most commonly used imaging modality for viewing the prostate. However, only 60% of tumors are visualized by TRUS, and the method often is used simply to localize the prostate, as a guide to biopsy. Nonetheless, it is said that in the hands of experts, TRUS detects extracapsular extension with accuracy between 58% and 86%.
MRI combines both MR parameters for a gross anatomical and functional classification of the prostate gland tissues. Multi-parametric prostate (mpMRI), on the other hand, is able to distinguish between the various anatomical zones of the prostate and has a good visual image of the anterior zone where some cancers may develop. (Birs et al., 2016: 8)
CT is responsible for mathematical measuring of extra-capsular extension to help with the treatment planning and Bone scan can be used to manage metastatic PCa, whoever this modality are not used for diagnosis. (Kelloff et al., 2009: 1456)
PET is useful in evaluating the pelvic lymph nodes was severely limited by bladder activity and streak artifacts. And although the quality of FDG-PET images of the pelvis has improved significantly with the use of iterative reconstruction algorithms
TRUS has the ability to diagnose and detect organs with cancer, Ultrasound imaging modality can provide a tissue diagnosis by fine-needle aspiration (FNA) and deliver therapy (interventional EUS).
While CT with or without MRI is having a ability to outline patient-specific representation of prostate gland location and pure mathematics. CT is not dependent on the bone remodeling by lesion, it shows more lasions. (Kelloff et al., 2009)
(CT) is one of the most frequently used hospital diagnostic tools and also one of the most cost-effective (Kim et al., 2010: 3689)
MRI is mostly desirable due to a higher signal-to-noise ratio (SNR), yielding advantages by contributing to improved structural and functional detail. Current receiver coil technology includes pelvic phased-array coils with or without the add-on of an endorectal coil(Hegde et al., 2013: 1036)
MRI does not impose radiation exposure on the patient. This advantage is important when imaging non-oncological patients or patients with a potentially curable oncological disease. Also multiparametric prostate MRI is used diagnose and investigate the prostate cancer antigen (Pca), whether it be through lesion visualization or by assisting in marked biopsies. (Birs et al., 2016)
It is generally accepted that FDG-PET has very low a sensitiveness to be helpful in the diagnosing of lymph node metastases during direct staging of prostate cancer (Schöder & Larson, 2004: 280)
According to Byrne & Jowell, 2002 ultrasound education in tumor size may be helpful to determine prognosis to some practitioners, but a challenging problem with EUS is that it cannot dependably separate inflammatory tissue from cancer. With EUS it may prove impracticable to advance the EUS investigation through the stenosis, 29 and in this situation some authors have suggested dilatation to allow for EUS evaluation. (Byrne & Jowell, 2002: 134)
Most cancers cannot be seen by current TRUS techniques, while MRI SPECT is proven its ability is limited when it comes to diagnostic accuracy, poor sensitivity and specificity. 99mTc- MDP bone scan is proven to be sensitive but is poor when it comes to the spatial resolution of the visceral disease and limited specificity. (Kelloff et al., 2009: 1456)
MRI is more expensive and is defined by considerably increased examination times. The procedure direction strongly depends on the imaging protocol ( such as the number and type of sequences). (Antoch & Bockisch, 2009: 114)
Studies consulted provide evidence that all mentioned studies are of importance in the clinical environment, however, their use will be determined on what the physician is hoping to find out. For example, ultrasound and Magnetic resonance can be used to localize and stage the organ containing cancer, while the bone scan is used to determine metastatic disease and CT helps with treatment planning. The advancement of modalities help in improving the quality of care but education is always need to be applied in order to be able to utilise this improvement.
- Antioch, G. & Bockisch, A. 2009. Combined PET/MRI: A new dimension in whole-body oncology imaging? European Journal of Nuclear Medicine and Molecular Imaging, 36(SUPPL. 1): 113–120.
- Birs, A., Joyce, P.H., Pavlovic, Z.J. & Lim, A. 2016. Diagnosis and Monitoring of Prostatic Lesions: A Comparison of Three Modalities: Multiparametric MRI, Fusion MRI/Transrectal Ultrasound (TRUS), and Traditional TRUS. Cureus.
- Hegde, J. V., Mulkern, R. V., Panych, L.P., Fennessy, F.M., Fedorov, A., Maier, S.E. & Tempany, C.M.C. 2013. Multiparametric MRI of prostate cancer: An update on state-of-the-art techniques and their performance in detecting and localizing prostate cancer. Journal of Magnetic Resonance Imaging.
- Heidenreich, A., Bolla, M., Joniau, S., Mason, M.D., Matveev, V., Mottet, N., Schmid, H., Kwast, T.H. Van Der, Wiegel, T. & Zattoni, F. 2011. Guidelines on Prostate Cancer. European Association of Urology.
- Kelloff, G.J., Choyke, P. & Coffey, D.S. 2009. Challenges in clinical prostate cancer: Role of imaging. American Journal of Roentgenology.
- Kim, D., Jeong, Y.Y. & Jon, S. 2010. A drug-loaded aptamer – Gold nanoparticle bioconjugate for combined ct imaging and therapy of prostate cancer. ACS Nano.
- National Cancer Registry. 2014. Cancer In South Africa 2014 Full Report. http://www.nicd.ac.za/index.php/centres/national-cancer-registry/# [22 May 2018]
- Penzkofer, T. & Tempany-Afdhal, C.M. 2014. Prostate cancer detection and diagnosis: The role of MR and its comparison with other diagnostic modalities – a radiologist’s perspective. NMR in Biomedicine.
- Schöder, H. & Larson, S.M. 2004. Positron emission tomography for prostate, bladder, and renal cancer. Seminars in Nuclear Medicine.