Prostate Cancer: Understanding Its Nature Through Pathology

1. Overview of Prostate Cancer

The prostate is a small gland about the size of a lemon, located below the bladder and surrounding the urethra in men. It produces part of the fluid in semen. Prostate cancer occurs when cells in the prostate gland grow abnormally and uncontrollably, with adenocarcinoma being the most common type [1].

It is the second most common cancer and the fifth leading cause of cancer-related death among men worldwide [1]. The risk of developing prostate cancer increases with age (particularly after age 50), family history, race (men of African ancestry have a higher risk), and dietary factors [1].

2. The Role of Pathology in Prostate Cancer Diagnosis

Pathology plays a central role in the definitive diagnosis and classification of prostate cancer [1, 2, 3]. The diagnostic process typically begins with a transrectal ultrasound (TRUS)-guided needle biopsy to obtain tissue samples.

The pathologist then examines the tissue samples under a microscope to:

• Determine the presence of cancer cells.
• Classify the type of cancer, most commonly adenocarcinoma.
• Assess the degree of differentiation of the cancer cells, which forms the basis for determining the Gleason score [1].
• Evaluate the extent of invasion and provide other prognostic information, such as the number of positive biopsy cores and the presence of perineural invasion [1]. Findings from the pathology report provide critical information for clinicians when making treatment decisions and assessing the patient's prognosis.

3. Gleason Grading System and Grade Groups

The Gleason grading system is used to classify the aggressiveness of prostate cancer based on the histologic appearance of cancer cells and is one of the most important independent prognostic factors [1].

3.1. Gleason Score and Its Significance

The Gleason grading system evaluates the degree of differentiation of prostate cancer based on architectural patterns. The pathologist assigns grades to the two predominant tumor patterns and adds them together to determine the Gleason score. In current practice, reported Gleason scores generally range from 6 to 10 [1, 2, 4]. A higher Gleason score indicates a greater likelihood of aggressive tumor behavior, rapid growth, and spread [1, 2]. 

3.2. Modern Grade Group System

To simplify and standardize communication of prostate cancer grading, the International Society of Urological Pathology (ISUP) introduced the Grade Group system in 2014 [1, 2]. The system classifies prostate cancer into five groups corresponding to different Gleason scores and prognostic categories [1, 2]:

The presence of a cribriform pattern in Grade Group 4 has particular prognostic significance and has been associated with a higher risk of biochemical recurrence, metastasis, and prostate cancer–specific mortality [5, 7, 8].

4. Other Pathological Factors Affecting Prognosis

In addition to the Gleason score and Grade Group, the pathology report provides several other important findings that help assess prognosis and guide treatment planning [2, 3].

4.1. Histologic Subtypes and Extent of Invasion

More than 95% of prostate cancers are adenocarcinomas [1]. Less common types, such as small cell carcinoma and urothelial carcinoma, have distinct characteristics and prognoses.

The extent of tumor invasion is an important prognostic factor, including:

• Extraprostatic extension: Cancer has spread beyond the prostate capsule.
• Seminal vesicle invasion: Cancer has extended into the seminal vesicles.
• Perineural invasion: Cancer cells grow along nerve fibers, which may indicate a greater potential for local spread.
• Lymphovascular invasion: This may be associated with an increased risk of distant metastasis [2, 3].

The number of positive biopsy cores and the percentage of cancer involvement in each core are also important indicators. Higher values may be associated with a greater likelihood of more extensive or aggressive disease [2].

4.2. Intraductal Carcinoma of the Prostate (IDC-P)

IDC-P refers to the proliferation of malignant cells within pre-existing prostatic ducts [1]. Although considered an in situ lesion, IDC-P is associated with aggressive invasive prostate cancer, poorer prognosis, and higher risks of biochemical recurrence, metastasis, and prostate cancer–specific mortality [1, 9, 10, 11, 12]. The presence of IDC-P may indicate more aggressive disease and has important implications for treatment decisions and prognosis.

5. When Should You See a Doctor?

Early-stage prostate cancer often causes no obvious symptoms. As the disease progresses, men may experience urinary symptoms such as difficulty urinating, weak urine flow, or increased urinary frequency, as well as hematuria, pelvic pain, or erectile dysfunction.

Prostate cancer screening may include a prostate-specific antigen (PSA) blood test and digital rectal examination (DRE) [13]. Men aged 50 and older, or those aged 40–45 with higher-risk factors such as a family history or African ancestry, should discuss prostate cancer screening with their physician to determine whether screening is appropriate and potentially facilitate early detection [13].

6. Frequently Asked Questions (FAQ)

1. What does a high Gleason score mean, and how is it different from Grade Group? A high Gleason score indicates a greater likelihood of aggressive cancer. Grade Group is a simplified system that categorizes Gleason scores into five groups, making it easier to communicate the tumor's grade and prognosis [1, 2, 4].
2. Is prostate cancer hereditary? Approximately 5–10% of cases may have a hereditary component, particularly when a father or brother was diagnosed before age 65. IDC-P may also be associated with BRCA2 gene mutations [1, 14].
3. How does IDC-P affect prognosis? IDC-P is associated with more aggressive prostate cancer and may be associated with higher disease stage, higher Gleason scores, larger tumor volume, and increased risks of recurrence, metastasis, and prostate cancer–specific mortality [1, 9, 10, 11, 12].
4. What are the benefits and risks of prostate cancer screening? Screening may facilitate early detection, but it can also lead to overdiagnosis and overtreatment of cancers that may not cause harm. The potential benefits and risks should be discussed with a physician [13].
5. What role does artificial intelligence play in the pathology of prostate cancer? AI is being investigated as a tool to assist with cancer detection, tumor quantification, and Gleason grading, with the potential to improve diagnostic accuracy and screening [3, 15].

7. References

• [1] Szentirmai, E., & Giannico, G. A. (2020). Intraductal carcinoma of the prostate. Pathologica, 112(1), 17–24. https://pmc.ncbi.nlm.nih.gov/articles/PMC8138500/.
• [2] van Leenders, G. J. L. H., van der Kwast, T. H., Grignon, D. J., Evans, A. J., Kristiansen, G., Kweldam, C. F., Litjens, G., McKenney, J. K., Melamed, J., Mottet, N., Paner, G. P., Samaratunga, H., Schoots, I. G., Simko, J. P., Tsuzuki, T., Varma, M., Warren, A. Y., Wheeler, T. M., Williamson, S. R., & Iczkowski, K. A. (2020). The 2019 International Society of Urological Pathology (ISUP) Consensus Conference on Grading of Prostatic Carcinoma. American Journal of Surgical Pathology, 44(8), e87–e99. https://pmc.ncbi.nlm.nih.gov/articles/PMC7382533/.
• [3] Liu, Y., Han, X., Chen, H., & Zhang, Q. (2025). Enhanced ISUP grade prediction in prostate cancer using multi-center radiomics data. Abdominal Radiology (New York), 50(9), 4301–4310. https://pmc.ncbi.nlm.nih.gov/articles/PMC12331822/.
• [4] Srigley, J. R., Delahunt, B., Egevad, L., Samaratunga, H., Yaxley, J., & Evans, A. J. (2016). One is the new six: The International Society of Urological Pathology (ISUP) patient-focused approach to Gleason grading. Canadian Urological Association Journal, 10(9–10), 339–341. https://pmc.ncbi.nlm.nih.gov/articles/PMC5085914/.
• [5] Gordetsky, J. B., Schaffer, K., & Hurley, P. J. (2022). Current Conundrums with Cribriform Prostate Cancer. Histopathology, 80(7), 1038–1040. https://pmc.ncbi.nlm.nih.gov/articles/PMC9675397/.
• [6] Kweldam, C. F., Kümmerlin, I. P., Nieboer, D., van Leenders, G. J. L. H., van der Kwast, T. H., & Steyerberg, E. W. (2016). Disease-specific survival of patients with invasive cribriform and intraductal prostate cancer at diagnostic biopsy. Modern Pathology, 29(6), 630–636. https://pubmed.ncbi.nlm.nih.gov/26939875/.
• [7] Iczkowski, K. A., Torkko, K. C., Kotnis, G. R., Mugler, K., & Han, B. (2011). Digital quantification of five high-grade prostate cancer patterns, including the cribriform pattern, and their association with adverse outcome. American Journal of Clinical Pathology, 136(1), 98–107. https://pubmed.ncbi.nlm.nih.gov/21685037/.
• [8] Kweldam, C. F., Wildhagen, M. F., Steyerberg, E. W., & van der Kwast, T. H. (2015). Cribriform growth is highly predictive for postoperative metastasis and disease-specific death in Gleason score 7 prostate cancer. Modern Pathology, 28(3), 457–464. https://pubmed.ncbi.nlm.nih.gov/25189638/.
• [9] Szentirmai, E., & Giannico, G. A. (2020). Intraductal carcinoma of the prostate. Pathologica, 112(1), 17–24. https://pubmed.ncbi.nlm.nih.gov/32202536/.
• [10] Varma, M. (2021). Intraductal Carcinoma of the Prostate: A Guide for Urologists and Pathologists. Advances in Anatomic Pathology, 28(4), 223–228. https://pubmed.ncbi.nlm.nih.gov/33990497/.
• [11] Tsuzuki, T. (2015). Intraductal carcinoma of the prostate: a comprehensive and updated review. Pathology International, 65(1), 1–12. https://pubmed.ncbi.nlm.nih.gov/25358604/.
• [12] Roberts, J. A. (2013). Intraductal Carcinoma of Prostate. Journal of Current Oncology, 3(1), 1–4. https://pmc.ncbi.nlm.nih.gov/articles/PMC3759629/.
• [13] MedlinePlus. (n.d.). Prostate Cancer Screening. https://medlineplus.gov/prostatecancerscreening.html.
• [14] Isaacsson Velho, P., Silberstein, J. L., Markowski, M. C., et al. (2018). Intraductal/ductal histology and lymphovascular invasion are associated with germline DNA-repair gene mutations in prostate cancer. Prostate, 78(5), 401–407. https://pubmed.ncbi.nlm.nih.gov/29368341/.
• [15] Nagpal, K., Foote, D., Liu, Y., et al. (2019). Development and validation of a deep learning algorithm for improving Gleason scoring of prostate cancer. NPJ Digital Medicine, 2, 48. https://pubmed.ncbi.nlm.nih.gov/31304394/.