The largest population-based study of gastrointestinal (GI) carcinoids ever reported shows that although the disease remains rare, it is increasing more rapidly than most other cancers.
Data from more than 25,000 patients collected over 3 decades was evaluated by Simone Mocellin, MD, PhD, from the Department of Surgery Oncology and Gastroenterology at the University of Padova School of Medicine in Italy, and colleagues. Their results were published in the December issue of theAnnals of Oncology.
The team found an age-adjusted annual percentage change (APC) in the number of GI carcinoids of 4.4%, which is greater than that for liver cancer (3.5%), thyroid cancer (3.5%), and lung cancer in women (3.0%), and only slightly less than esophageal adenocarcinoma (4.8%).
Age-adjusted mortality is also increasing annually (APC, 3.5%), the researchers found.
Just why GI carcinoids are increasing is unclear, although the researchers hypothesize that the growing number of endoscopic procedures (during which asymptomatic tumors are discovered) could account for part of the increase. However, the fact that the increase in diagnosis is accompanied by an increase in mortality suggests that the rise in GI carcinoids is not due to more aggressive diagnosis of indolent tumors, they write.
In addition, the researchers note that speculation that an increase in GI carcinoid is linked to an increased use of proton-pump inhibitors is "purely theoretical."
Rare Tumors
GI carcinoid is 1 of 3 main subtypes of neuroendocrine tumors that originate in cells of the neuroendocrine system. The others are pancreatic endocrine tumors and lung carcinoid. Fourteen cell types in the GI mucosa might give rise to GI carcinoid.
Because of the relative rarity of GI carcinoids, previous studies have relied on small numbers of patients or on studies that include all neuroendocrine tumors. Dr. Mocellin's team looked at 18 cancer registries in the United States. Their data were all age-adjusted and normalized to the American population in 2000.
Nearly three-quarters (72.7%) of patients with GI carcinoid are white, and the median age is 60 years. Men and women are equally likely to have the disease, which is most frequently found in the small bowel (38.0%) or the rectum (34.0%).
GI carcinoid sites with the greatest increase are the stomach (APC, 7.0%) and the rectum (APC, 7.8%). The only site that is decreasing is the appendix (APC, –3.6%), the researchers report.
From 2000 to 2009, the average annual rate of GI carcinoid was 2.5 cases per 100,000. The rate was higher for blacks (4.6 cases per 100,000). Those diagnosed from 2000 to 2009 were less likely to present with distant disease than with localized or regional deisease.
According to Surveillance, Epidemiology, and End Results data, the annual incidence rate of all cancers is 475 per 100,000, whereas the annual incidence rate for all carcinoid tumors is 3.5 per 100,000. GI carcinoids represent only 0.52% of all new cancers, but 71.4% of all carcinoid tumors. By comparison, the annual incidence of GI cancer is 65 per 100,000, and GI cancers represented 13.6% of all malignancies from 2002 to 2009.
Overall Favorable Prognosis
Surgery remains the preferred treatment for primary and some advanced GI carcinoid, although metastatic disease is often resistant to chemotherapy, the researchers explain. It is a slow-growing tumor, with an overall favorable prognosis, and patients with GI carcinoid have a relatively good life expectancy, they note.
For localized GI carcinoid, the 5-year survival rate is 95.6%; for regional disease, it is 86.5%; and for distant disease, it is 52.4%.
The authors have disclosed no relevant financial relationships.
Ann Oncol. 2013;24:3040-3044. Abstract
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