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Cancer Association of South Africa (CANSA) Fact Sheet on Carcinoid Tumours Introduction Carcinoid cancer and related neuroendocrine tumours (NETs) are small, slow growing tumours found mostly in the gastrointestinal system, but can be in other parts of the body such as the pancreas and the lung. Since most of these grow very slowly, compared to other cancers, it usually takes many years before they become sizable or cause symptoms. [Picture Credit: Carcinoid Tumours] Carcinoid tumours and other NETs usually originate in hormone- producing cells that line the small intestine or other cells of the digestive tract. They can also occur in the pancreas, testes, ovaries, or lungs. Carcinoid tumours can produce an excess of hormone-like substances, such as serotonin, bradykinin, histamine, and prostaglandins. Excess levels of these substances can sometimes result in a diverse set of symptoms called carcinoid syndrome. Other NETs can produce other hormonal substances causing a variety of other syndromes. When carcinoid tumours occur in the digestive tract or pancreas, the substances they produce are released into a blood vessel that flows directly to the liver (portal vein), where enzymes destroy them. Therefore, carcinoid tumours that originate in the digestive tract generally do not produce symptoms Researched and Authored by Prof Michael C Herbst [D Litt et Phil (Health Studies); D N Ed; M Art et Scien; B A Cur; Dip Occupational Health; Dip Genetic Counselling; Dip Audiometry and Noise Measurement; Diagnostic Radiographer; Medical Ethicist] Approved by Ms Elize Joubert, Chief Executive Officer [BA Social Work (cum laude); MA Social Work] November 2021 Page 1 unless the tumours have spread to the liver. The hormones secreted by other NETs, particularly those in the pancreas, do not necessarily require spread to the liver to cause symptoms. When carcinoid tumours have spread to the liver, the liver is unable to process the substances before they begin circulating throughout the body. Depending on which substances are being released by the tumours, the person will have the various symptoms of carcinoid syndrome, insulinoma syndrome (it originates in the beta cells of the pancreas, which releases an unregulated amount of insulin - the patient may feel symptoms that include sweating, increased heat rate, shaking, paleness and a decreasing state of consciousness), Zollinger Ellison syndrome (a condition in which there is increased production of the hormone gastrin), and VIPoma syndrome (also known as Verner Morrison syndrome of watery diarrhoea, hypokalaemia, and achlorhydria). Carcinoid tumours of the lungs, testes, and ovaries also cause symptoms without having spread, because the substances they produce bypass the liver and can sometimes circulate widely in the bloodstream. Cingam, S.R., Kashyap, S. & Karanchi, H. 2020. “Carcinoid tumors are slow-growing tumors arising from neuroendocrine cells and capable of secreting a variety of peptides and neuroamines. The common primary sites are the gastrointestinal (GI) tract (60%) followed by the tracheobronchial tree (25%), but other primaries may occur in the ovaries or kidneys. The most common location of carcinoids is the small intestine. The term carcinoid is usually used for well-differentiated and low to intermediate grade neuroendocrine tumors, and the term neuroendocrine carcinoma is used for the less frequent, poorly differentiated and high-grade neuroendocrine tumors.” Hilal, L., Jammal, M., Khalifeh, I., Tfayli, A. & Youssef, B. 2019. “Head and neck neuroendocrine tumors (NET) are a rare type of cancer. NET can be classified according to the histopathological features. The typical carcinoid tumor is a well- differentiated tumor that is the least common among other types. Owing to its indolent behavior and variable radiological and pathological features, treatment of carcinoid tumors remains a challenge. “ Carcinoid Tumours A carcinoid tumour starts in the hormone-producing cells of various organs, primarily the gastrointestinal tract (such as the stomach and intestines) and lungs, but also the pancreas, testicles (in males) or ovaries (in females). A carcinoid tumour is classified as a neuroendocrine tumour, which means it starts in cells of the neuroendocrine system that produce hormones. Origin of carcinoid tumours • 39% occur in the small intestine • 15% occur in the rectum • 10% occur in the bronchial system of the lungs • 7% occur in the appendix • 5% to 7% occur in the colon (large bowel) • 2% to 4% occur in the stomach • 2% to 3% occur in the pancreas • About 1% occur in the liver Researched and Authored by Prof Michael C Herbst [D Litt et Phil (Health Studies); D N Ed; M Art et Scien; B A Cur; Dip Occupational Health; Dip Genetic Counselling; Dip Audiometry and Noise Measurement; Diagnostic Radiographer; Medical Ethicist] Approved by Ms Elize Joubert, Chief Executive Officer [BA Social Work (cum laude); MA Social Work] November 2021 Page 2 Howe, J.R. 2020. “Carcinoid tumors are being seen with increasing frequency by surgeons and have become the most common type of tumors of the small bowel. These tumors produce a variety of hormones, which leads to many unique characteristics in terms of symptoms and presentation. Our knowledge of the natural history and treatment of these tumors continues to evolve, and this article will summarize these advances.” Tumour Grade and Tumour Stage Tumour grade and stage are terms used to describe the severity of a tumour, while tumour grade describes the appearance of cancerous cells in the tissue by examining them under a microscope. Tumour stage encompasses: • The location of the tumour. • The size and/or extent of the original tumour. • Whether cancer cells have spread to lymph nodes or anywhere else in the body. • The number of tumours present. Doctors use tumour grade, cancer stage, and a patient’s age and general health to decide the course of treatment for the patient and determine prognosis. Prognosis describes all factors including the disease course, cure rate, chances of survival, and risk of recurrence of cancer. What are the cancer stages? Different systems of cancer staging are used to describe the types of cancer. Below is a common method in which stages are ranged from 0 to IV. • Stage 0: The tumour is confined to its place of origin (in situ) and has not spread to nearby tissue. • Stage I: The tumour is located only in the original organ, is small, and has not spread. • Stage II: The size of the tumour is large but has not spread. • Stage III: The tumour has become larger and may have spread to surrounding tissues and/or lymph nodes. • Stage IV: The tumour has spread to other distant organs of the body, which is known as the metastasis stage. TNM staging Another common staging method used for cancer is the TNM system, which stands for tumour, node (which means spread of the tumour to lymph nodes), and metastasis. When a patient’s cancer is staged using the TNM system, a number will be present along with the letter. This number signifies the extent of the disease in each category - tumour, node, and metastases. Another system of cancer staging divides cancer into five stages, which include: • In situ: Abnormal cells are present but have not spread to nearby tissue. • Localized: Cancer is located only in the original organ and shows no sign of its spread. • Regional: Cancer has spread to nearby lymph nodes, tissues, or organs. • Distant: Cancer has spread to distant parts of the body. Researched and Authored by Prof Michael C Herbst [D Litt et Phil (Health Studies); D N Ed; M Art et Scien; B A Cur; Dip Occupational Health; Dip Genetic Counselling; Dip Audiometry and Noise Measurement; Diagnostic Radiographer; Medical Ethicist] Approved by Ms Elize Joubert, Chief Executive Officer [BA Social Work (cum laude); MA Social Work] November 2021 Page 3 • Unknown: The stage cannot be figured out due to a lack of enough information. What are the cancer grades? Cancer grades are based on examination of the suspected tissue sample under a microscope. This involves surgically removing a piece of the suspected cancerous tissue and sending it to the lab for analysis. The entire procedure is known as a biopsy. A doctor who specializes in diagnostic tests (pathologist) examines the cells of the tissue and determines whether they are harmless (benign or noncancerous) or harmful (malignant or cancerous). They describe the microscopic appearance of the cells and assign a numerical “grade” to most cancers. Generally, a lower grade indicates slow-growing cancer and a higher grade indicates fast-growing cancer. The most commonly used grading system is as follows: • Grade I: Cancer cells that look like normal cells but are not growing rapidly. • Grade II: Cancer cells that don't look like normal cells with their growth being faster than normal cells. • Grade III: Cancer cells that look abnormal and have the potential to grow rapidly or spread more aggressively. Sometimes, the following system can be used: • GX: Grade cannot be assessed (undetermined grade) • G1: Well-differentiated (low grade) • G2: Moderately differentiated (intermediate grade) • G3: Poorly differentiated (high grade) • G4: Undifferentiated (high grade) Incidence of Carcinoid Tumours in South Africa The National Cancer Registry (2017) does not provide any information regarding the incidence of Carcinoid Tumours. Carcinoid Syndrome Many patients with metastatic carcinoid tumour will manifest the signs and symptoms of abnormal hormone production - the malignant carcinoid syndrome. Serotonin (5-hydroxytryptamine [5-HT]), synthesised by the tumour from tryptophan and metabolised to 5-HIAA, which appears in the urine, is particularly important because urinary 5-HIAA levels are used to monitor the course of carcinoid syndrome. However, the relationship of serotonin levels to symptoms of the clinical carcinoid syndrome is uncertain. Carcinoid tumours also release the enzyme kallikrein, which acts on alpha -globulin to produce 2 bradykinin and its precursor, lysyl-bradykinin, both of which can induce flushing. Serotonin may be responsible for intestinal hypermotility and hypersecretion, but it probably does not cause the characteristic flushing that occurs with the carcinoid syndrome. Researched and Authored by Prof Michael C Herbst [D Litt et Phil (Health Studies); D N Ed; M Art et Scien; B A Cur; Dip Occupational Health; Dip Genetic Counselling; Dip Audiometry and Noise Measurement; Diagnostic Radiographer; Medical Ethicist] Approved by Ms Elize Joubert, Chief Executive Officer [BA Social Work (cum laude); MA Social Work] November 2021 Page 4
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