Prostatea walnut-shaped gland in the male reproductive system that is responsible for producing semen - a bodily fluid that acts as a vessel for sperm transport during ejaculation neuroendocrine tumours (NETs), also known as carcinoid tumours of the prostate, are a very rare type of neuroendocrine tumoura tissue mass that forms from groups of unhealthy cells that develops in the prostate gland.
The prostate is a walnut-shaped gland in the male reproductive system. It sits below the bladdera hollow, muscular sac in the pelvis that stores urine, and in front of the rectum (end of the small bowelportion of the digestive system that digests food (small bowel) and absorbs salts and water (large bowel); also called intestines). The prostate is responsible for producing semen, a bodily fluid that acts as a vessel for sperm transport during ejaculation, and nourishment to keep the sperm alive outside of the body. It also has a small role in the urinary system, as the thin tube (ureter) that runs through the bladder to the penis is passed through the prostate.
Neuroendocrine cancers are a complex group of tumours that develop in the neuroendocrine system, which is responsible for regulating important bodily functions such as heart rate, bloodthe red bodily fluid that transports oxygen and other nutrients around the body pressure and metabolism. They most commonly develop in the gastro-intestinal tract, pancreasa long, flat organ that sits between the stomach and the spine that plays a key role in digestion and blood sugar regulation, and the lungs; however, they can develop anywhere in the body. These tumours develop from neuroendocrine cellsthe basic structural and functional unit of all living things, which are responsible for receiving signals from the nervous system and producing hormones and peptides (small proteins) in response.
Prostate NETs are most commonly found in men over 55 years of age. However, anyone with a prostate – including teenagers, transgender women, non-binary individuals, and intersex people – can develop this disease at any age.
Types of Prostate Neuroendocrine Tumours
Because of how rare prostate NETs are, there has been limited research done into the types of this disease. However, some distinct subtypes have been identified.
Well-Differentiated Neuroendocrine Tumour of the Prostate
Well-differentiated neuroendocrine tumours of the prostate is a very rare form of cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs that are characterised by relatively ‘normal looking’ cells under the microscope. This subtype is often associated with multiple endocrine neoplasia type 2B (MEN2B). Well-differentiated neuroendocrine tumours of the prostate are often categorised as low-grade (slow growing), however can metastasise if left untreated.
Neuroendocrine Carcinomas of the Prostate
Neuroendocrine carcinomas of the prostate are a rare type of cancer that are characterised by abnormal looking cancer cells under the microscope. There are two primary subtypes of this disease.
Small Cell Carcinoma of the Prostate
Small cell neuroendocrine carcinomacancer arising from tissues that line organs of the prostate is a very rare form of cancer that is often associated with adenocarcinomas of the prostate. This type of tumour is often classified as a type of extrapulmonary small cell lung cancer, as the cells present are identical under a microscope. Unfortunately, small cell neuroendocrine carcinomas of the prostate are often aggressive, and may not have as good of a prognosisto predict how a disease/condition may progress and what the outcome might be as other types of prostate cancers.
Large Cell Carcinoma of the Prostate
Large cell neuroendocrine carcinoma of the prostate is a very rare form of cancer that is often associated with adenocarcinomacancer arising from mucus-producing glands in organs of the prostate. Unfortunately, large cell neuroendocrine carcinomas of the prostate are often aggressive, and may not have as good of a prognosis as other types of prostate cancers.
Adenocarcinoma with Neuroendocrine Differentiation
Adenocarcinoma with neuroendocrine differentiation is a very rare form of cancer that looks like an adenocarcinoma of the prostate under the microscope, but is positive for a neuroendocrine marker during biopsyremoval of a section of tissue to analyse for cancer cells and blood testing. Similarly to adenocarcinoma of the prostate, these types of tumours can be aggressive and metastasise, but can have a good prognosis when caught early.
Treatment-related Neuroendocrine Prostatic Carcinoma
Treatment-related neuroendocrine prostatic carcinoma (tNEPC) is a very rare form of cancer that develops after long-term androgen deprivation therapy (ADT)a type of hormone therapy used to reduce testosterone levels to treat prostate cancer. It is most commonly seen after treatment of small cell neuroendocrine carcinoma of the prostate or large cell neuroendocrine carcinoma of the prostate, and can be associated with adenocarcinoma of the prostate. Unfortunately, tNEPC is often aggressive, and may not have as good of a prognosis as other types of prostate cancer.
Treatment
If a prostate NET is detected, it will be staged and graded based on size, metastasiswhen the cancer has spread to other parts of the body, also known as mets, and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodea small lump or mass of tissue in your body) indicates whether the cancer has spread to nearby lymph nodessmall bean-shaped structures that filters harmful substances from lymph fluid.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissuea group of cells that work together to perform a function.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localisedaffecting only one area of body cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Gradea description of how abnormal cancer cells and tissue look under a microscope when compared to healthy cells II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for prostate NETs may include:
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence, potentially including:
-
- Prostatectomycomplete or partial removal of the prostate gland.
-
- Lymphadenectomysurgical removal of lymph node(s).
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells, potentially including:
-
- Brachytherapya type of internal radiation therapy where radioactive material is placed inside or near a tumor to deliver targeted radiation.
-
- External beam radiation therapy (EBRT)a type of radiation therapy that uses high-energy rays or particles to target the cancer from a machine outside of the body.
- Hormone therapymedication that alters the levels of certain hormones in the body, such as oestrogen and progesterone, such as androgen deprivation therapy (ADT) – not recommended for treatment-related neuroendocrine prostatic carcinoma.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Prostate Neuroendocrine Tumour Treatment and Fertility
Treatment for prostate NETs may make in difficult to conceive a child. If fertility is important to you, discuss your options with your doctor and a fertility specialist prior to the commencement of treatment.
Risk factors
Because of how rare prostate NETs are, there has been little research done into the riskthe possibility that something bad will happen factors of this disease.
Symptoms
Some patients with prostate NETs will appear asymptomatic in the early stages of disease. As the tumour progresses, some of the following symptoms may appear:
- Changes in urination, such as:
-
- Polyuriafrequent urination.
-
- Feeling like your bladder isn’t empty after urination.
-
- Slow urine flow.
-
- Weaker bladder.
-
- Loss of bladder control.
- Incontinenceloss of control over release of urine or faeces.
- Blood in urine and/or semen.
- Erectile dysfunctionimpaired or abnormal function; not working properly.
- Pain when ejaculating.
- Unexplained weight loss.
- Bone pain.
- Fatiguea state of extreme tiredness or exhaustion, can be physical or mental.
- Carcinoid syndrome (rare), which carries its own set of symptoms:
-
- Facial flushing (usually red or purple in the face, neck, and/or upper chest).
-
- Diarrhoeafrequent discharge of watery or loose stools from the body.
-
- Wheezing.
-
- Abdominal pain.
-
- Carcinoid heart disease (plaques on the heart muscle caused by excess hormonea chemical substance produced by glands in the endocrine system that regulates various functions in the body production).
-
- Faecal urgency.
-
- Fatigue.
-
- Skin changes, such as red or purple spots on the face, neck, and/or upper chest.
- Paraneoplastic syndromesa group of rare disorders that occur when the immune system has a reaction to a cancerous tumour within the body (rare).
- Hypercalcaemiaexcess levels of calcium in the blood (rare).
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have a prostate NET, they may order the following tests to confirm the diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Digital rectal examinationan examination conducted by a urologist where a finger (or digit) is inserted into the rectum to feel the anus (DRE).
- Imagingtests that create detailed images of areas inside the body tests, potentially including:
-
- TRUS (transrectal ultrasound)a type of ultrasound that involves inserting a device (known as a transducer) into the rectum to produce sound waves and create images of the rectum, prostate gland and surrounding tissues in greater detail; also known as an endorectal ultrasound.
-
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
-
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- Blood teststesting done to measure the levels of certain substances in the blood, such as to check your PSA level.
- Urine teststesting done to measure the levels of certain substances in the urine.
- Biopsy.
References
- Pathology Outlines – Small Cell Neuroendocrine Carcinoma of the Prostate
- Pathology Outlines – Treatment related neuroendocrine prostatic carcinoma
- Radiopaedia - Adenocarcinoma of the prostate with neuroendocrine differentiation
- Radiopaedia – Large cell neuroendocrine carcinoma of the prostate
- Radiopaedia - Small Cell Neuroendocrine Carcinoma of the Prostate
- Radiopaedia - Well-differentiated neuroendocrine tumours of the prostate