Accounts for approximately 2-3% of gastrointestinal tumors, and less than 1% of all malignancies.
Estimated 10,590 new cases of small bowel cancer will occur in 2019, and 1590 patients will die of this disease.
Affects men and women relatively equally with an incidence of 2.6 per hundred thousand for men and 2.0 per hundred thousand for women.
Median age at diagnosis is 66 years.
The incidence is increasing with an annual percent increase of 1.8%: while other gastrointestinal malignancies including the esophagus, stomach, colon, and rectum, where the incidence has decreased.
Small bowel carcinomas present at an earlier age, are predominately seen in males and African-American patients compared to large bowel adenocarcinomas.
About 30% of small bowel adenocarcinomas present with high-grade stage IV disease whereas 20% of colon cancers present with high-grade stage IV disease.
Over last 30 years SBC has become the second most common primary small bowel malignancy, recently surpassed by carcinoid tumor.
Difficult to diagnose due to non specific symptoms, slow growth rate and lack of specific diagnostic tests.
Can be primary adenocarcinoma, carcinoid or sarcomatous lesion or metastatic in nature.
The four most common histologies of cancer: adenocarcinomas, neuroendocrine tumors, gastrointestinal stromal tumors, and lymphomas..
Small bowel adenocarcinoma accounts for approximately one third of all small intestinal malignancies.
Adenocarcinoma of the small bowel arises predominantly from the duodenum, 57-65%, with a decline in frequency toward the distal small bowel.
Other major tumor types are neuroendocrine carcinomas, sarcomas, and lymphomas.
Risk factors for the development of small bowel adenocarcinomas include an association between SBA and colorectal cancer, suggesting a shared common pathogenesis.
The risk of SBA is increased in patients with inflammatory bowel disease and hereditary colorectal cancer syndromes.
Predisposing conditions include: genetic diseases that are accompanied by gastrointestinal polyps, and chronic inflammatory bowel disease.
Familial syndromes like Lynch syndrome, Peutz-Jeghers syndrome and familial adenomatous polyposis, as well as chronic inflammatory conditions like Crohn’s disease and celiac disease increase the risk of developing small bowel adenocarcinoma.
Small bowel adenocarcinomas having inferius stage-adjusted prognosis in comparison to colorectal cancers.
Average age at diagnosis 50-70 years, with a slight male predominance.
There has been a slight increasing incidence of small bowel adenocarcinomas, especially duodenal adenocarcinomas in recent years.
Most small bowel adenocarcinomas arise in the duodenum and patients with such lesions have a worse prognosis than patients with jejunal or ileal adenocarcinomas of the small bowel.
Distant or nodal metastases, T4 tumor, positive surgical margins, poorly differentiated histology, duodenal or ileal location, male sex, age greater than 55 years, and African American ethnicity are associated with poor prognosis of small bowel adenocarcinomas.
About half of the patients present with abdominal pain.
Presenting symptoms are usually nonspecific and include abdominal pain, nausea, weight loss, fatigue, jaundice, and G.I. tract bleeding.
One third of patients with small bowel adenocarcinomas have metastatic disease at the time of diagnosis.
60-70% of patients are stage III or IV when diagnosed.
5-year disease specific survival is 65% in stage I disease, whereas it is 4% in stage IV.
Along with satge, T4 lesions, surgical margin positivity,and lymph node invasion are poor risk factors.
In curatively resected lesions, recurrence is usually distant, rather than local with liver, peritoneum, locoregional recurrence and abdominal wall involvement in order of frequency.
Surgical resection of the primary tumor is most effective treatment.
There is no accepted adjuvant treatment protocol.
FOLFOX adjuvant therapy is associated with improved survival.
The most efficacious agents include fluoropyrimidine plus oxaliplatinum.