Carcinoid tumours are the type of tumours that form in the neuroendocrine system. The neuroendocrine system comprises a series of glands that are responsible for the production of hormones, which have crucial bodily functions to perform.
Carcinoid tumours are usually slow-growing and do not have any signs or symptoms until the later stages. A large percentage of carcinoid tumours are formed in the appendix and small intestines. However, they can also form in the GI tract, stomach, colon, rectum, lungs, pancreas and ovaries or testicles. Wherever they arise, carcinoid tumours affect the cells that produce hormones.
There are three types of carcinoid tumours:
- 1. Slow-growing carcinoid tumours: As the name says, slow-growing tumours grow slowly and are smaller in size. They don’t readily spread to other organs.
- 2. Fast-growing carcinoid tumours: Fast-growing tumours grow quickly and can spread to other parts of the body.
- 3. Hormone-secreting carcinoid tumours: Also called functioning tumours, hormone-secreting carcinoid tumours secrete hormone-like substances, namely histamine, serotonin, bradykinin and prostaglandin in excess quantity and eventually lead to carcinoid syndrome. This leads to various symptoms such as pain, diarrhoea, vomiting, fatigue, weight loss, etc.
Carcinoid tumours are slow-growing in most cases and show signs and symptoms in later stages. The symptoms associated with this disease are specific to the organ that it forms in. Following are some of the common symptoms associated with carcinoid tumours:
- Severe diarrhoea
- Hot flushes
- Increased heart rate
- Sudden changes in blood pressure
- Loss of appetite
- Weight loss
Symptoms could be organ-specific, i.e., tumours formed in the GI tract may cause blood in stool, diarrhoea, rectal pain and bleeding. Carcinoid tumours formed in the lungs, on the other hand, may cause chest pain, shortness of breath, wheezing, weight gain in the midsection and upper back, etc.
As mentioned before, carcinoid tumours produce hormones and other chemicals, which lead to a range of health complications:
- Carcinoid Syndrome: Carcinoid syndrome causes hot flushes, diarrhoea, and breathing difficulties, weight loss, among other symptoms.
- Carcinoid Heart Disease: Certain chemicals produced by these tumours lead to thickening of the heart walls, valves and blood vessels and eventually cause leaking of heart valves and heart failure. This condition can be treated via valve replacement surgery and medications.
- Cushing Syndrome: Lung carcinoid tumours stimulate excess production of cortisol hormone in the body and cause a condition called Cushing syndrome. If left unaddressed, Cushing syndrome causes thinning of arms and legs, face roundness, weight gain, easy bruising and stretch marks, etc.
To conclude, any symptom that persists for more than two weeks should not be ignored and brought to the notice of the physician as early as possible.
Although the exact cause for the carcinoid tumour is unknown. Researchers have identified a few factors that increase the risk of developing this disease. Carcinoid tumour formation may be associated with one or more factors listed below:
- Genetics: Individuals with the genetic condition, Multiple Endocrine Neoplasia Type 1 (MEN1) are at a higher risk of developing carcinoid tumours. Neurofibromatosis type 1 is another genetic condition that is associated with an increased risk of carcinoid tumour formation.
- Race: Africans are found to be more susceptible to carcinoid tumours.
- Gender: The risk of developing carcinoid tumours is relatively higher among women than men.
- Age: Carcinoid tumours are slow-growing and are usually diagnosed in the 40s or 50s.
- Other Conditions: Diseases such as pernicious anaemia and Zollinger-Ellison syndrome, which lead to increased acid production in the stomach, also increase the risk of carcinoid tumours.
Multiple tests are available for the detection and definitive diagnosis of carcinoid tumours.
a. Blood and Urine Tests: Hormone-secreting carcinoids may lead to excess levels of certain hormones in the body. Abnormal levels of these hormones and the by-products that are formed when these hormones break down can be detected through blood tests and urine tests.
b. Imaging Tests: Imaging tests, namely PET/CT scan, MRI scan, octreotide scan and X-ray, help pinpoint the tumour location. The results from these tests also support treatment planning.
c. Endoscopy: An endoscope may be inserted through the throat (bronchoscope) or rectum (colonoscope) to diagnose carcinoid tumours in various parts of the body. To detect carcinoid tumours of the small intestine, capsule endoscopy may be recommended where the patient is asked to swallow a pill-sized camera before the inspection.
d. Radionuclide scanning: This is a special diagnostic method where the patient is administered a small amount of radioactive tracer that goes and binds to the carcinoid tumours once it enters the bloodstream. This test helps in determining the regions where the tumours are present.
e. Biopsy: Biopsy involves the removal of a small portion of the tissue from the tumour and examining it under the microscope to study the aggressiveness and grade of the tumour. The tissue sample may be collected by inserting a fine needle, or it may be excised during surgery.
The treatment options available for carcinoid tumours are surgery, radiation therapy, chemotherapy, immunotherapy, targeted therapy and hormone therapy. The treatment plans for the carcinoid tumours are made after considering multiple factors such as the type of the tumour, its location and size, the stage, the grade and most importantly, the overall condition of the patient.
a. Surgery: Surgery is the main line of treatment for carcinoid tumours. Multiple surgical methods are available to operate the tumours based on their location:
- Local Excision: Local excision involves the removal of the tumour and a small portion of the healthy tissues surrounding it.
- Resection: During resection, the part of the organ that is affected by the carcinoid tumour or the entire organ is removed.
- Cryosurgery: This is a minimally invasive procedure that kills tumour cells by freezing them. A specialised instrument called a cryoprobe is used to freeze the tumour cells to death.
- Fulguration: This procedure burns off the tumour cells using electric current. This method is safe and effective for certain types of carcinoid tumours.
- Radiofrequency Ablation: Radiofrequency ablation is another minimally invasive procedure that kills the tumour cells using high-energy radio waves.
b. Radiation Therapy: Radiation therapy uses high-energy radiation beams to destroy cancer cells. Radiation may either be delivered externally (through linear accelerator) or internally (brachytherapy).
c. Systemic therapy: Systemic therapies are those that find and attack tumours throughout the body, including the ones that are too small to detect.
- Chemotherapy uses potent drugs that are administered orally or injected into the muscle or vein to destroy the tumour cells.
- Hormone therapy for carcinoid tumours works by blocking the tumours from producing excess hormones.
- Immunotherapy is a systemic therapy where the body’s own immune cells are collected, re-engineered and injected back into the body. Once inside the body, these re-engineered cells find and attack the tumour cells.
- Targeted therapy works by targeting the cancer-specific genes, proteins or the cellular environment that are contributing to the growth and survival of carcinoid tumours. This treatment reduces the damage to the healthy tissues by precisely targeting the tumour cells.
Frequently Asked Questions
1. Are carcinoid tumours considered cancer?
Carcinoid tumours can be both benign and malignant. In a few cases, carcinoid tumours are fast-growing and more readily spread to other organs or cause complications such as carcinoid syndrome by producing certain hormones in excess levels.
2. Are carcinoid tumours treatable?
Yes, carcinoid tumours are treatable. There are multiple treatment options available for carcinoid tumours today.
Since carcinoid tumours are slow-growing in most cases, early detection and timely treatment are usually feasible.
3. Can a blood test detect carcinoid tumours?
Yes, a blood test helps detect carcinoid tumours. The abnormal levels of certain hormones, such as serotonin, cortisol, etc., caused due to carcinoid tumours can be easily detected through blood tests. However, additional tests are required for a conclusive diagnosis.
4. What is the prognosis for my carcinoid tumour?
Each case of carcinoid tumour is different, and therefore, the prognosis will be different too. The disease prognosis for any patient is made based on several factors, such as:
- The location of the tumour
- If the tumour is benign or malignant
- Status of the treatment given
For more accurate information on your disease prognosis, you should have a detailed discussion with your doctor.