What is Carcinoid tumor?
Carcinoid tumors originate from neuroendocrine cells and are much slower growing compared with adenocarcinoma. The term carcinoid (“karzinoid”) was termed because it was noted that these tumors are “cancer-like” in appearance but more benign in behavior. The most common locations for carcinoid tumor in the GI tract are the rectum, appendix, and small intestine.
What are the symptoms of carcinoid tumor?
In the early stages carcinoid tumors do not cause any symptoms. The majority of carcinoids are located in the rectum and identified incidentally at the time of colonoscopy. Rectal carcinoids that are larger may produce rectal bleeding, pain, constipation, or diarrhea. Carcinoid tumors of the appendix and ileum (small intestine) produce a chemical called serotonin. When these tumors spread to the liver, the serotonin can enter the circulation and cause a condition known as carcinoid syndrome. Symptoms of carcinoid syndrome include facial flushing, diarrhea, and wheezing. Rectal carcinoids do not secrete any chemicals and thus the symptoms of carcinoid syndrome do not occur.
How is carcinoid tumor diagnosed?
Rectal carcinoids are typically diagnosed incidentally at the time of colonoscopy. Carcinoid tumors of the appendix are generally diagnosed after an appendectomy for appendicitis. Small bowel carcinoid tumors may cause obstruction, bleeding or carcinoid syndrome (flushing, diarrhea, wheezing) if they have spread to the liver. Urine, blood, and imaging tests such as CT scan of your chest and abdomen, MRI, or octreotide scans may be necessary to diagnose and define the extent of disease.
How is rectal carcinoid tumor treated?
Rectal carcinoid tumors tend to be very small (<1cm) at the time of diagnosis and thus the chance of metastasis is low (<5%). These tumors can generally be removed by tranasanal excision (removal through the rectum), endoscopic resection, or TEM (Transanal Endoscopic Microsurgery) or TAMIS (Transanal Minimally Invasive Surgery). It is recommended that individuals with rectal carcinoid tumors that are larger than 2 cm, have evidence of muscular invasion, or lymph node spread undergo low anterior resection (LAR). LAR involves removal of the rectum and draining lymph nodes. The procedure may be performed laparoscopically or with robotic-assisted surgery in the majority of cases. In some cases, traditional open surgery may be necessary. Mid-sized rectal tumors 1-2 cm may need further investigation with a rectal ultrasound or MRI to determine if there is muscular invasion or lymph node spread. The recommendation for local excision or more extensive surgery will be made based on these tests and your overall health. Sometimes small tumors incompletely excised during endoscopy may need to be re-evaluated with a repeat biopsy or rectal ultrasound to make sure there is no residual tumor. The area may also need to be marked with a “tattoo” for later identification. If there is no residual tumor, further surgery may not be necessary. In cases of residual disease, the polyp site can be excised by transanal or TAMIS techniques.
How is carcinoid tumor of the appendix treated?
Tumor size is the best indicator of lymph node spread. Tumors <1 cm are generally treated with simple appendectomy as long as there is no lymphovascular invasion, involvement of the mesoappendix (the lymph nodes draining the appendix) or a positive margin. Tumors >2 cm have a higher chance of lymph node involvement or spread to other organs. For these tumors, a right hemicolectomy (removal of the right colon including appendix, cecum and terminal ileum and connection of the ileum to the transverse colon) is recommended. Treatment of tumors between 1 -2 cm must be individualized based on the risk of recurrence and risk of surgery. For tumors with lymphovascular invasion, involvement of the mesoappendix, or a positive margin (tumors at the base of the appendix) a right hemicolectomy is usually recommended.
How is carcinoid tumor of the small intestine treated?
Carcinoid tumors of the small intestine tend to be multiple and are often associated with carcinoid syndrome. After thorough imaging to identify the extent of disease, a multi-team approach along with a liver surgeon may be necessary to treat the small bowel and liver disease. Small bowel resection to remove the tumor and draining lymph nodes is typically necessary whereas the liver may be treated in a number of ways including resection and ablation. Call to make an appointment with Dr. Zaghiyan in her office in Los Angeles for a thorough evaluation and treatment recommendations.