Overview of carcinoid tumors
Carcinoid tumors are low-grade malignant tumors originated from endocrine cells in the gastrointestinal tract and other organs. The cells are mostly confined, infiltrating and slow-growing, and are less likely to metastasize despite the fact that their histological structure resembles that of carcinoma and has a tendency to malignant transformation, so they are called carcinoid tumors. Carcinoid tumor is a rare disease in clinic. Its clinical, histochemical and biochemical features may vary according to the site of occurrence and the active factors secreted by endocrine cells. In serious cases, the secreted 5-hydroxytryptamine (5-HT), kinins, histamine and other biologically active substances may cause vasomotor disorders, gastrointestinal symptoms, cardiac and pulmonary pathologies, and other carcinoid syndromes. Carcinoid tumors tend to develop from the lower part of the mucosal layer and can occur anywhere from the esophagus to the rectum, with the following frequencies: distal appendix, other parts of the appendix, small intestine, rectum, stomach and duodenum, and esophagus is rare. About 10% of carcinoid tumors are found in the bronchus, thymus, thyroid, ovary, cervix, and testis.
Causes
The cause of carcinoid tumors is unclear, and some carcinoid tumors are genetically linked. Endocrine cells with carcinoid tumors may take up amine precursors from outside the cell, and through the action of intracellular aminodecarboxylase, the amine precursors can form corresponding amines (e.g., dopamine, 5-hydroxytryptophan, etc.) and polypeptide hormones, causing vasomotor disorders, gastrointestinal symptoms, cardiac and pulmonary pathologies, and other carcinoid syndromes.
Symptoms
Early stage patients are mostly asymptomatic, and the following symptoms may appear in middle and late stages.
1. Flushing of skin
It is seen in more than 90% of patients and is the main clinical manifestation. It is mostly an episodic change of bright red skin on face and neck. At the beginning, it lasts only 10-15 minutes, and can be accompanied by fever, tearing, etc. It occurs once every few weeks, but later it can be increased to several times a day, and the duration is getting longer and longer, which can be up to a few hours.
2. Gastrointestinal symptoms
Seen in about 80% of patients. The main manifestations are episodic abdominal cramps, bowel sounds, episodic watery diarrhea, and a sense of urgency and heaviness. The number of diarrhea per day varies, up to twenty or thirty times. Intestinal peristalsis is increased and enhanced, and incomplete intestinal obstruction is secondary to tumor or intestinal wall fibrosis.
3. Respiratory symptoms
Episodic asthma, rales in the lungs, wheezing episodes related to 5-HT and histamine, etc.
4. Cardiovascular symptoms
Carcinoid heart disease occurs in 11%-60% of patients and is characterized by the appearance of deposits in the endocardium and valves, mostly in the right heart, causing severe tricuspid regurgitation. The right heart is often enlarged, and the corresponding organic murmur of valve damage can be heard. There may be jugular venous rupture. Myocardial fibrosis and constrictive pericarditis may occur; patients with carcinoid heart disease often show right heart insufficiency with edema as the main manifestation due to right heart involvement, and left heart involvement is less common.
5. Others
Excessive sweating, angioneurotic edema, emotional abnormalities, etc.
Examination
1.5-HT measurement
The serum 5-HT content of patients with carcinoid syndrome is often obviously elevated, mostly 83～510μmol/L (normal reference value is 11～5lμmol/L).
2.5-Hydroxyindoleacetic acid (5-HIAA) measurement
5-HIAA is the metabolite of 5-hydroxytryptamine in the body. In patients with carcinoid syndrome, urinary 5-HIAA excretion increases, often exceeding 78.5 μmol/24 h, and is generally in the range of 156.9-3138 μmol/24 h (normal value <47.1 μmol/24 h). 24-hour urinary 5-hydroxyindoleacetic acid excretion fluctuates greatly, and it is affected by the influence of food. For example, after eating potatoes, bananas, pineapples, the amount of urinary 5-hydroxyindoleacetic acid excretion increases, so it is necessary to repeat several times to test the urine diagnosis is more reliable.
3.Imaging examination
Most of the tumors are small, X-ray examination and endoscopy are not easy to find the tumor. For more obvious lesions, barium meal, endoscopy or CT can find mucosal thickening, submucosal mass or luminal narrowing. Endoscopic ultrasound can significantly improve the detection rate of gastrointestinal tumors compared with traditional ultrasound, and can even find tiny tumors in the intestinal wall of 2~3 mm. MRI has no obvious advantage compared with CT.
4. Mesoiodobenzylguanidine (MIBG) scanning
MIBG and norepinephrine are similar in structure, radioactive iodine labeled MIBG can be used to detect neuroendocrine tumors, sensitivity
The sensitivity is 55%～70% and the specificity is 95%.
5. Growth inhibitory receptor scintigraphy (SRS) and positron emission tomography (PET) imaging
87% of carcinoid tumors have growth inhibitory receptor expression, therefore, SRS technique has been developed in recent years for localized diagnosis of carcinoid tumors. In fact, this method is applicable to the diagnosis of many kinds of neuroendocrine tumors.
6. Excitation test
For those who are highly suspected of carcinoid tumor and the urinary 5-hydroxyindoleacetic acid excretion does not increase, stimulation test can be performed. The test method is to use 5% dextrose 500ml intravenous drip, measure blood pressure and pulse every half a minute, and after the blood pressure and pulse are stabilized, 1μg of epinephrine can be injected intravenously, and if there is no reaction, 1μg can be added every 15 minutes until there is a reaction. However, the maximum dose should not exceed 15 μg each time. If there is still no response with 15 μg, this test is no longer performed. The provocation test can cause severe hypotension and bronchospasm, so this test should be performed with extreme caution.
Diagnosis
Endoscopic elevated mass with smooth surface and no abnormality in the upper mucosa, hard, similar to polyps, yellow or grayish white, suggesting the possibility of carcinoid tumor; serum 5-HT level of 83-510μmol/L, as well as pathological and histological and immunohistochemical examination of carcinoid tumor can make a definitive diagnosis.
Differential diagnosis
Differential diagnosis should be made with the following diseases.
(1) Menopausal flushing: It is a kind of long-lasting flushing of the skin, but it is usually not severe, and there is a feeling of warmth of the skin. There is no cyanosis of the skin, nor abdominal pain, diarrhea, wheezing and other symptoms.
(2) Neurogenic edema: Sudden onset of limited edema of soft tissues due to various stimuli. It is a kind of allergic angioneurotic edema, which often occurs in the face, lips and eyelids, and can also occur in the oral cavity and pharynx; laryngeal edema can cause asphyxia in severe cases.
(3) Systemic mastocytosis: Because of the increased production of histamine, it causes skin flushing, erythema of the skin and mucous membranes, and urticaria-like changes. It lasts for a long time and diarrhea may occur. When the skin is flushed, histamine increases in the blood.
(4) Diarrhea without skin flushing: It needs to be distinguished from other causes of diarrhea, such as gastrin (gastrin) tumors can cause ulcerative disease and diarrhea.
(5) Endocardial lesions: Tricuspid valve lesions of the heart caused by carcinoid tumors need to be differentiated from rheumatism, right ventricular papillary muscle dysfunction, and infective endocarditis.
Treatment
1. Surgical treatment
It is applicable to carcinoid tumors without metastasis. Carcinoid tumors occurring in appendix, bronchus and ovary can be treated surgically. If it has caused intestinal obstruction or intussusception in the intestinal tract, even if it has metastasis, it needs to be treated surgically. If the symptoms are more serious and the effect of medical treatment is not good, the tumor can be removed, which cannot cure but can relieve the symptoms in a longer period of time. Tumor diameter <lcm can be treated endoscopically, 1~2cm can be resected locally, and >2cm can be expanded surgically. For those with liver metastasis, lobectomy or resection of metastatic tumor should be carried out when resecting the primary foci. Those who cannot be resected should have hepatic artery cannula embolization or perfusion.
2. Chemotherapy
Commonly used drugs include fluorouracil (FU), streptozocin, dacarbazine, doxorubicin, etoposide, cisplatin, etc. However, the effect of chemotherapy is limited. However, the effect of chemotherapy is limited.
3. Biological therapy
Interferon has certain efficacy, commonly used interferon α. Carcinoid syndrome can be treated with growth inhibitor analogues (e.g. octreotide) alone, which can effectively alleviate the symptoms and improve the biochemical indexes, but the effect of anti-tumor proliferation is not obvious. For gastrointestinal carcinoid tumors with metastasis, combined application of surgical tumor reduction and long-acting growth inhibitor analogs can effectively prolong the survival time of patients.
4.Targeted drug therapy
Such as tyrosine kinase inhibitors.
5.Targeted radiation therapy
For gastrointestinal carcinoid tumors with metastasis, peptide receptor-targeted radiation therapy can also be performed using growth inhibitor analogs labeled with radionuclides (mainly 111In, 90Y, 177Lu).
Questions you may be concerned about
Can carcinoid tumor take Panax ginseng and American ginseng?
It is not recommended to take Panax ginseng powder for carcinoid tumor, and you can take American ginseng in moderation under the guidance of doctor.
Carcinoid tumors are low-grade malignant tumors originated from endocrine cells in gastrointestinal tract and other organs. Cells are mostly limited, infiltrative and slow-growing, and less metastatic despite of the cancer-like tissue structure and malignant tendency.
Panax ginseng is sweet, slightly bitter, warm in nature, and belongs to the liver and stomach meridians. It has the effects of dispersing blood stasis and stopping bleeding (removing stasis and stopping bleeding), subduing swelling and resolving pain (eliminating swelling and pain). It is used in treating hemoptysis, hematemesis, epistaxis, hematochezia, metrorrhagia (excessive menstrual flow or dribbling), traumatic hemorrhage, stabbing pain in the chest and abdomen, and swelling and pain in falling and beating.
Radix Panax Ginseng is sweet, slightly bitter and cool in nature, and belongs to the heart, lung and kidney meridians. It has the functions of tonifying qi and nourishing yin, clearing heat and generating fluids, and is used for qi deficiency and yin deficiency, deficiency heat and tiredness, coughing and wheezing, phlegm and blood, internal heat and thirst (internal heat accompanied by symptoms such as eating more, drinking more and urinating more), and dry mouth and throat.
As Panax ginseng powder has the effect of activating blood circulation and removing blood stasis (promoting blood circulation and eliminating blood stasis in the body), it is not conducive to wound healing and there is a risk of bleeding, therefore, patients with carcinoid tumors are not recommended to take Panax ginseng powder. On the other hand, American ginseng is a kind of traditional Chinese medicine to replenish qi, which can be taken in moderation under the guidance of doctor to help improve the condition.
After discomfort occurs, patients should consult doctor in time and choose medication under doctor’s guidance, and should not use medication on their own.
Prognosis
The prognosis of digestive tract carcinoid tumor is good, and metastasis depends on the size of the tumor, the probability of metastasis of <1cm tumor is 2%, the metastasis rate of 1~2cm tumor is 50%, and the metastasis rate of >2cm tumor reaches 80%~90%.