Prostate Cancer Diagnosis: Understanding the Process

Prostate Cancer Diagnosis is a critical step in managing this common condition affecting men. Early and accurate diagnosis significantly improves treatment outcomes and survival rates. If you’re navigating concerns about prostate health, understanding the diagnostic journey is essential. This article delves into the comprehensive process of prostate cancer diagnosis, from initial screenings and examinations to advanced tests and staging.

Initial Steps in Prostate Cancer Diagnosis

The journey to diagnosing prostate cancer often begins with routine screenings or when a man experiences symptoms that raise concerns. These initial steps are designed to detect potential problems early, allowing for timely intervention and management.

Prostate Cancer Screening: PSA and DRE

Prostate cancer screening aims to identify the disease in its early stages, often before symptoms appear. The two primary screening tests are the prostate-specific antigen (PSA) blood test and the digital rectal exam (DRE).

The PSA test measures the level of prostate-specific antigen in your blood. PSA is a protein produced by both normal and cancerous prostate cells. Elevated PSA levels can indicate prostate cancer, but they can also be caused by other conditions, such as benign prostatic hyperplasia (BPH) or prostatitis.

The digital rectal exam (DRE) is a physical examination where a healthcare professional inserts a gloved, lubricated finger into the rectum to feel the prostate gland. This allows the doctor to assess the size, shape, and texture of the prostate, and identify any abnormalities that might suggest cancer.

Most medical guidelines recommend discussing prostate cancer screening with your healthcare provider starting at age 50. However, men with higher risk factors, such as African American men or those with a family history of prostate cancer, may consider starting screening earlier. The decision to undergo screening should be made in consultation with your doctor, considering your individual risk factors and preferences.

Digital Rectal Exam (DRE)

The digital rectal exam is a simple yet important part of the initial prostate cancer diagnosis process. It allows for a direct physical assessment of the prostate gland.

During a DRE, the patient may be asked to lean forward over an examination table or lie on their side with knees bent. The healthcare professional will gently insert a lubricated, gloved finger into the rectum. The prostate gland is located in front of the rectum, making it accessible for examination through the rectal wall.

Alt text: A medical professional performing a Digital Rectal Exam (DRE) to check the prostate gland.

During the exam, the doctor feels for any lumps, bumps, or hard areas on the prostate, which could be signs of cancer. They also assess the overall size and consistency of the gland. While a DRE alone cannot diagnose prostate cancer, it can detect abnormalities that warrant further investigation. It’s a quick procedure, usually causing only mild and temporary discomfort.

Prostate-Specific Antigen (PSA) Test

The prostate-specific antigen (PSA) test is a blood test used to measure the level of PSA in the blood. It is a primary tool in prostate cancer screening and diagnosis.

PSA is produced by both normal and malignant prostate cells, and a small amount of PSA circulates in the blood. The PSA test measures the concentration of PSA in a blood sample, typically reported in nanograms per milliliter (ng/mL).

While an elevated PSA level can be an indicator of prostate cancer, it is not cancer-specific. Factors other than cancer can also raise PSA levels, including:

• Benign Prostatic Hyperplasia (BPH): Enlargement of the prostate gland, common in older men.
• Prostatitis: Inflammation or infection of the prostate gland.
• Urinary Tract Infection (UTI)
• Ejaculation: PSA levels can temporarily increase after ejaculation.
• Prostate Biopsy or Surgery: Procedures involving the prostate can elevate PSA.
• Certain Medications: Some medications may affect PSA levels.

Because of these factors, an elevated PSA level does not automatically mean prostate cancer is present. If a PSA test result is higher than normal, your doctor will consider your age, medical history, and other risk factors to determine the next steps. Often, the PSA test is repeated to confirm the elevated level. If the PSA remains high or continues to rise, further diagnostic tests are usually recommended, such as imaging tests or a prostate biopsy.

Advanced Diagnostic Tests

If initial screening tests like PSA and DRE suggest a potential issue, or if a man is experiencing symptoms, advanced diagnostic tests are used to further investigate and determine if prostate cancer is present.

Prostate Ultrasound

Prostate ultrasound, specifically transrectal ultrasound (TRUS), is an imaging technique that uses sound waves to create images of the prostate gland. It’s often used when a DRE or PSA test raises concerns.

During a TRUS, a thin, lubricated probe is inserted into the rectum. This probe emits sound waves that bounce off the prostate gland, and these echoes are converted into images on a monitor. TRUS is generally a quick and relatively painless procedure.

Prostate ultrasound helps to:

• Visualize the prostate gland: It provides detailed images of the prostate’s size, shape, and internal structure.
• Detect abnormalities: Ultrasound can help identify suspicious areas within the prostate that might be cancerous.
• Guide prostate biopsy: TRUS is commonly used to guide the needle during a prostate biopsy, ensuring accurate tissue sampling from specific areas of concern.

While ultrasound can detect abnormalities, it cannot definitively diagnose prostate cancer. If suspicious areas are seen on the ultrasound, a prostate biopsy is usually necessary to confirm the presence of cancer cells.

Prostate MRI

Prostate Magnetic Resonance Imaging (MRI) is a powerful imaging technique that uses magnetic fields and radio waves to create detailed pictures of the prostate gland and surrounding tissues. It is increasingly used in prostate cancer diagnosis and management.

Prostate MRI offers several advantages:

• High-resolution imaging: MRI provides very detailed images of the prostate, allowing for better visualization of the gland’s anatomy and any abnormalities.
• Detection of suspicious lesions: MRI can detect areas within the prostate that are highly suspicious for cancer, often more accurately than ultrasound.
• Staging and risk assessment: MRI can help assess the extent of the cancer within the prostate and whether it has spread outside the gland, aiding in staging and risk stratification.
• Guidance for targeted biopsy: MRI can identify specific areas within the prostate that are most likely to contain aggressive cancer. This information can be used to perform a targeted biopsy, where tissue samples are taken specifically from these suspicious regions, improving the accuracy of biopsy results.

Different types of MRI techniques are used in prostate cancer diagnosis, including:

• Multiparametric MRI (mpMRI): This is the most common type of MRI for prostate cancer. It combines several MRI techniques to provide comprehensive information about the prostate tissue, including its structure, cellular density, and blood flow. mpMRI is highly effective in detecting and characterizing prostate cancer.
• Contrast-enhanced MRI: Involves injecting a contrast dye into a vein before the MRI scan. The dye helps to highlight blood vessels and tissues, making certain abnormalities more visible.
• MRI with endorectal coil: Uses a small device called an endorectal coil, inserted into the rectum to improve the image quality of the prostate. This technique can provide even more detailed images, especially for local staging.

Prostate MRI is a non-invasive procedure, but it requires lying still inside the MRI machine for a period of time. It is a valuable tool in prostate cancer diagnosis, helping to improve detection, risk assessment, and biopsy accuracy.

Prostate Biopsy

A prostate biopsy is the definitive diagnostic procedure for prostate cancer. It involves removing small tissue samples from the prostate gland for microscopic examination by a pathologist. This is the only way to confirm the presence of cancer cells.

There are two main types of prostate biopsies:

• Transrectal Prostate Biopsy (TRUS-guided biopsy): This is the most common type of prostate biopsy. It is usually performed in conjunction with a transrectal ultrasound (TRUS).

  During a TRUS-guided biopsy, a thin ultrasound probe is inserted into the rectum to visualize the prostate. A biopsy needle is then inserted through the rectal wall and into the prostate to collect tissue samples. Typically, multiple samples (cores) are taken from different areas of the prostate to increase the chance of detecting cancer if it is present.

  Alt text: Illustration of a Transrectal Prostate Biopsy procedure, showing needle insertion guided by ultrasound.

• Perineal Prostate Biopsy: This type of biopsy is less common and involves inserting the biopsy needle through the perineum, the skin between the scrotum and the anus, to reach the prostate. It may be used in specific situations, such as when a transrectal approach is not feasible or when there is concern about infection risk.

Prostate biopsies are typically performed as outpatient procedures. Local anesthesia is usually used to numb the area and minimize discomfort. After the biopsy, patients may experience some mild discomfort, bleeding from the rectum, blood in the urine or semen, and a small risk of infection. Antibiotics are often prescribed to reduce the risk of infection.

The tissue samples obtained during the biopsy are sent to a pathology lab where they are examined under a microscope to determine if cancer cells are present. If cancer is found, the pathologist will also assess its grade and other characteristics, which are crucial for determining prognosis and treatment options.

Understanding Biopsy Results

Once a prostate biopsy is performed, the tissue samples are analyzed to provide crucial information about the presence and characteristics of prostate cancer. Key components of biopsy results include the Gleason score and grade group, and biomarker tests.

Gleason Score and Grade Group

The Gleason score and grade group are systems used to classify the aggressiveness or grade of prostate cancer. They are based on the microscopic appearance of the cancer cells in the biopsy samples.

The Gleason score is determined by a pathologist who examines the tissue samples and identifies the two most predominant patterns of cancer cells. Each pattern is assigned a grade from 1 to 5, based on how abnormal the cancer cells look compared to normal prostate cells. Grade 1 cells are the most well-differentiated (most similar to normal cells) and Grade 5 cells are the least differentiated (most abnormal).

The Gleason score is calculated by adding the grades of the two most common patterns. For example, if the most common pattern is Grade 3 and the second most common pattern is Grade 4, the Gleason score would be 3+4=7.

Gleason scores range from 2 to 10, with higher scores indicating more aggressive cancer. Scores are generally categorized as:

• Gleason 6 (3+3): Well-differentiated, low-grade cancer, typically less aggressive.
• Gleason 7 (3+4 or 4+3): Intermediate-grade cancer, with varying levels of aggressiveness. (Note: 3+4 and 4+3, while both Gleason 7, have different prognoses with 4+3 generally considered more aggressive.)
• Gleason 8-10: Poorly differentiated, high-grade cancer, more aggressive and likely to grow and spread quickly.

The Grade Group is a more recent classification system recommended by the World Health Organization (WHO) and the American Joint Committee on Cancer (AJCC). It simplifies the Gleason scoring system into five grade groups, from 1 to 5, which directly correlate with prognosis.

• Grade Group 1: Gleason score ≤ 6
• Grade Group 2: Gleason score 3+4=7
• Grade Group 3: Gleason score 4+3=7
• Grade Group 4: Gleason score 4+4=8, or 3+5=8, or 5+3=8
• Grade Group 5: Gleason score 9-10

The Gleason score and Grade Group are crucial factors in determining the prognosis of prostate cancer and guiding treatment decisions. Higher Gleason scores and Grade Groups indicate a higher risk of cancer progression and recurrence.

Prostate Cancer Biomarker Tests

Prostate cancer biomarker tests are increasingly used to provide additional information about the characteristics of prostate cancer, beyond the Gleason score and Grade Group. Biomarkers are substances found in body tissues, fluids, or blood that can indicate the presence or nature of a disease.

Biomarker tests for prostate cancer can be used for several purposes:

• Risk stratification: To better assess the risk of cancer progression in men with newly diagnosed prostate cancer, especially those with low or intermediate-risk disease. These tests can help decide whether active surveillance, immediate treatment, or more aggressive therapy is appropriate.
• Prediction of treatment response: To predict how likely a cancer is to respond to certain treatments, such as radiation therapy, hormone therapy, or chemotherapy.
• Prognosis: To provide a more accurate prognosis or outlook for men with prostate cancer.
• Detection of aggressive disease: Some biomarker tests can help identify men who are more likely to have aggressive or rapidly growing cancers.

Types of prostate cancer biomarker tests include:

• Genomic tests: These tests analyze the genes within the prostate cancer cells to look for specific genetic alterations that can influence cancer behavior and treatment response. Examples include Oncotype DX Prostate, Decipher, and Prolaris.
• Protein-based tests: These tests measure the levels of specific proteins in prostate tissue or urine that are associated with cancer aggressiveness. Examples include PCA3 and SelectMDx.

Biomarker tests are not routinely recommended for all men with prostate cancer, but they can be valuable in specific situations, particularly for men with early-stage disease to refine risk assessment and personalize treatment decisions. The use of biomarker tests is evolving, and their role in prostate cancer management continues to be studied.

Detecting Cancer Spread and Staging

Once prostate cancer is diagnosed through biopsy, further tests may be needed to determine if the cancer has spread beyond the prostate gland. This process is called staging, and it is essential for determining the extent of the disease and guiding treatment strategies.

Imaging Tests for Cancer Spread

If there is a concern that prostate cancer may have spread, imaging tests are used to look for evidence of metastasis (spread) to other parts of the body. These tests are typically recommended for men with higher-risk prostate cancer, based on Gleason score, PSA level, and other factors.

Common imaging tests used to detect prostate cancer spread include:

• Bone Scan: A bone scan is a nuclear medicine imaging technique that can detect areas of abnormal bone metabolism, which may indicate cancer spread to the bones. A radioactive tracer is injected into a vein, and it accumulates in areas of bone turnover. Bone scans are particularly useful for detecting metastatic prostate cancer, as bone is a common site of spread.
• Computerized Tomography (CT) Scan: CT scans use X-rays to create detailed cross-sectional images of the body. CT scans of the abdomen and pelvis can help detect if prostate cancer has spread to lymph nodes in the pelvis or to other organs.
• Magnetic Resonance Imaging (MRI): MRI can also be used to look for cancer spread beyond the prostate. Pelvic MRI can assess for spread to seminal vesicles, lymph nodes, or surrounding tissues. Whole-body MRI may be used in some cases to look for distant metastases.
• Positron Emission Tomography (PET) Scan: PET scans are nuclear medicine imaging techniques that use a radioactive tracer, typically a glucose analog (FDG), to detect metabolically active cells, such as cancer cells. While traditional FDG-PET scans are not always highly sensitive for prostate cancer, newer PET tracers specific for prostate cancer, such as PSMA-PET scans, are increasingly used.
• Prostate-Specific Membrane Antigen (PSMA) PET Scan: PSMA-PET scans use a radioactive tracer that targets prostate-specific membrane antigen (PSMA), a protein found on the surface of most prostate cancer cells. PSMA-PET scans are highly sensitive and specific for detecting prostate cancer, including metastatic disease. They are particularly useful for detecting recurrence after treatment and for staging higher-risk prostate cancer.

The choice of imaging tests depends on the individual patient’s risk factors, clinical situation, and the information needed to guide treatment decisions.

Prostate Cancer Stages

Prostate cancer staging is a system used to describe the extent of the cancer, including the size of the tumor, whether it has spread to nearby tissues, lymph nodes, or distant sites. The stage of prostate cancer is a crucial factor in determining prognosis and treatment options.

The TNM staging system is the most commonly used system for prostate cancer, where:

• T (Tumor): Describes the size and extent of the primary tumor in the prostate.
• N (Nodes): Indicates whether the cancer has spread to regional lymph nodes.
• M (Metastasis): Indicates whether the cancer has spread to distant sites (metastasis).

Prostate cancer stages range from Stage 1 to Stage 4:

• Stage 1 Prostate Cancer (T1, N0, M0): The cancer is small, confined to the prostate gland, and not palpable on DRE or visible on imaging. It is typically found incidentally during a TURP procedure for BPH. PSA level may be low or intermediate, and Grade Group is 1.
• Stage 2 Prostate Cancer (T2, N0, M0): The cancer is still confined to the prostate gland but is larger than Stage 1 or involves more of the prostate. Stage 2 is further subdivided into 2A, 2B, and 2C based on tumor size, location within the prostate, PSA level, and Grade Group.
• Stage 3 Prostate Cancer (T3 or T4, N0, M0): The cancer has spread beyond the prostate gland to nearby tissues, such as the seminal vesicles (T3) or bladder neck, rectum, or pelvic wall (T4), but has not spread to lymph nodes or distant sites. Stage 3 is further subdivided into 3A, 3B, and 3C based on the extent of local spread, PSA level, and Grade Group.
• Stage 4 Prostate Cancer (Any T, N1 or M1): Stage 4 indicates advanced prostate cancer that has spread beyond the prostate to regional lymph nodes (N1) or distant sites (M1), such as bones, lungs, or liver. Stage 4 is further subdivided into 4A and 4B based on the site of metastasis.

The stage of prostate cancer, along with Gleason score, PSA level, and other factors, is used to determine the risk category (low, intermediate, high, or very high risk) and guide treatment recommendations.

Prostate Cancer Prognosis and Survival Rates

Prostate cancer prognosis refers to the likely course and outcome of the disease. It is influenced by several factors, including the stage of the cancer, Gleason score, PSA level, patient’s age and overall health, and treatment received.

Prostate cancer survival rates are statistical measures that indicate the percentage of patients with prostate cancer who are alive for a certain period after diagnosis, typically 5 years or 10 years. These rates are based on large population studies and provide a general outlook for groups of patients with similar characteristics.

Overall, the prognosis for prostate cancer is generally good, especially when detected early and treated appropriately. Many men with prostate cancer live long and healthy lives.

Key factors influencing prognosis and survival rates:

• Stage: Early-stage prostate cancer (Stage 1 and 2) confined to the prostate has the best prognosis, with nearly 100% 5-year survival rates. As the stage advances (Stage 3 and 4), and the cancer spreads beyond the prostate, the prognosis becomes less favorable, and survival rates decrease.
• Gleason Score and Grade Group: Higher Gleason scores and Grade Groups indicate more aggressive cancers with a higher risk of progression and a less favorable prognosis.
• PSA Level: Higher PSA levels at diagnosis are generally associated with a less favorable prognosis.
• Age and Overall Health: Younger men and those with better overall health tend to have a better prognosis and can tolerate more aggressive treatments.
• Treatment: Effective treatment significantly improves prognosis. Treatment options are tailored to the stage, grade, and risk category of the cancer.

It is important to note that survival statistics are based on historical data and may not reflect the outcomes of current patients due to advances in diagnosis and treatment. Individual prognosis can vary widely, and it is best discussed with your healthcare team, who can consider all relevant factors in your specific case.

Conclusion

Prostate cancer diagnosis is a multi-step process that involves initial screening, physical examinations, blood tests, advanced imaging, and biopsy. Understanding this process is crucial for men navigating concerns about prostate health. Early and accurate diagnosis is paramount for effective management and improving outcomes for prostate cancer. If you have concerns about prostate cancer or are experiencing symptoms, it is essential to consult with a healthcare professional for appropriate evaluation and guidance. Open communication with your medical team is key to navigating the diagnostic journey and making informed decisions about your health.

References

1. DeVita VT Jr, et al., eds. Cancer of the prostate. In: DeVita, Hellman, and Rosenberg’s Cancer: Principles and Practice of Oncology. 12th ed. Wolters Kluwer; 2023. Accessed Sept. 24, 2024.
2. Prostate cancer treatment (PDQ) — Patient version. National Cancer Institute. https://www.cancer.gov/types/prostate/patient/prostate-treatment-pdq. Accessed Sept. 24, 2024.
3. Prostate cancer early detection. National Comprehensive Cancer Network. https://www.nccn.org/guidelines/guidelines-detail?category=2&id=1460. Accessed Sept. 24, 2024.
4. Cancer stat facts: Prostate cancer. National Cancer Institute. https://seer.cancer.gov/statfacts/html/prost.html. Accessed Sept. 26, 2024.
5. Partin AW, et al., eds. Campbell-Walsh-Wein Urology. 12th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed Sept. 24, 2024.
6. Taplin M, et al. Clinical presentation and diagnosis of prostate cancer. https://www.uptodate.com/contents/search. Accessed Sept. 24, 2024.
7. Hematuria (blood in the urine). National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/urologic-diseases/hematuria-blood-urine. Accessed Oct. 7, 2024.
8. Niederhuber JE, et al., eds. Prostate cancer. In: Abeloff’s Clinical Oncology. 6th ed. Elsevier; 2020. https://www.clinicalkey.com. Accessed Sept. 24, 2024.
9. Sartor AO. Risk factors for prostate cancer. https://www.uptodate.com/contents/search. Accessed Sept. 24, 2024.
10. Sartor AO. Chemoprevention strategies in prostate cancer. https://www.uptodate.com/contents/search. Accessed Sept. 24, 2024.
11. Prostate cancer screening (PDQ) — Patient version. National Cancer Institute. https://www.cancer.gov/types/prostate/patient/prostate-screening-pdq. Accessed Sept. 24, 2024.
12. AskMayoExpert. Prostate cancer: Screening (adult). Mayo Clinic; 2023.
13. Fowler GC, et al., eds. Prostate and seminal vesicle ultrasonography and biopsy. In: Pfenninger and Fowler’s Procedures for Primary Care. 4th ed. Elsevier; 2020. https://www.clinicalkey.com. Accessed Oct. 16, 2024.
14. Prostate MRI. RadiologyInfo.org. https://www.radiologyinfo.org/en/info/mr_prostate. Accessed Oct. 17, 2024.
15. Yang XJ. Interpretation of prostate biopsy. https://www.uptodate.com/contents/search. Accessed Oct. 16, 2024.
16. Biomarker testing for cancer treatment. National Cancer Institute. https://www.cancer.gov/about-cancer/treatment/types/biomarker-testing-cancer-treatment. Accessed Nov. 24, 2024.
17. Genomic diagnostic testing for prostate cancer. Urology Care Foundation. https://www.urologyhealth.org/educational-resources/genomic-diagnostic-testing-for-prostate-cancer. Accessed Nov. 24, 2024.
18. Prostate cancer. National Comprehensive Cancer Network. https://www.nccn.org/guidelines/guidelines-detail?category=2&id=1459. Accessed Sept. 24, 2024.
19. Richie JP. Localized prostate cancer: Risk stratification and choice of initial treatment. https://www.uptodate.com/contents/search. Accessed Sept. 24, 2024.
20. Taplin M, et al. Initial staging and evaluation of males with newly diagnosed prostate cancer. https://www.uptodate.com/contents/search. Accessed Sept. 24, 2024.
21. American College of Surgeons. Prostate. In: AJCC Cancer Staging System. American College of Surgeons; 2023. https://online.statref.com. Accessed Aug. 1, 2024.
22. Population-based cancer survival statistics overview. National Cancer Institute. https://surveillance.cancer.gov/survival. Accessed Oct. 17, 2024.
23. Tepper JE, et al., eds. Prostate cancer. In: Gunderson & Tepper’s Clinical Radiation Oncology. 5th ed. Elsevier; 2021. https://www.clinicalkey.com. Accessed Sept. 24, 2024.
24. Pisters LL, et al. Cryotherapy and other ablative techniques for the initial treatment of prostate cancer. https://www.uptodate.com/contents/search. Accessed Nov. 24, 2024.
25. Murad V, et al. MR-guided focused ultrasound focal therapy for prostate cancer. Magnetic Resonance Imaging Clinics of North America. 2024; doi:10.1016/j.mric.2024.04.001.
26. Abida W, et al. Management of advanced prostate cancer with germline or somatic homologous recombination repair deficiency. https://www.uptodate.com/contents/search. Accessed Nov. 23, 2024.
27. Gulley J. Immunotherapy for castration-resistant prostate cancer. https://www.uptodate.com/contents/search. Accessed Nov. 23, 2024.
28. Immune checkpoint inhibitors. National Cancer Institute. https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/checkpoint-inhibitors. Accessed Nov. 23, 2024.
29. Dawson NA, et al. Overview of treatment for castration-resistant prostate cancer (CRPC). https://www.uptodate.com/contents/search. Accessed Nov. 24, 2024.
30. Distress management. National Comprehensive Cancer Network. https://www.nccn.org/guidelines/guidelines-detail?category=3&id=1431. Accessed Sept. 24, 2024.
31. Thompson RH, et al. Radical prostatectomy for octogenarians: How old is too old? The Journal of Urology. 2006; doi:10.1016/j.urology.2006.05.031.
32. Choline C-11 injection (prescribing information). Mayo Clinic PET Radiochemistry Facility; 2024. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=203155. Accessed Nov. 24, 2024.
33. Woodrum DA, et al. Targeted prostate biopsy and MR-guided therapy for prostate cancer. Abdominal Radiology. 2016; doi:10.1007/s00261-016-0681-3.
34. Agarwal DK, et al. Initial experience with da Vinci single-port robot-assisted radical prostatectomies. European Urology. 2020; doi:10.1016/j.eururo.2019.04.001.
35. Gettman MT, et al. Current status of robotics in urologic laparoscopy. European Urology. 2003; doi:10.1016/S0302-2838(02)00579-1.
36. Krambeck AE, et al. Radical prostatectomy for prostatic adenocarcinoma: A matched comparison of open retropubic and robot-assisted techniques. BJU International. 2008; doi:10.1111/j.1464-410X.2008.08012.x.
37. What are radiopharmaceuticals? International Atomic Energy Agency. https://www.iaea.org/newscenter/news/what-are-radiopharmaceuticals. Accessed Nov. 24, 2024.