Duodenum starts where stomach ends. It is first part of the small intestine and ends in the jejunum. The draining channel to drain bile from liver also ends in duodenum - called as common bile duct. Cancer arising from duodenum is duodenal cancer. It is a very rare kind of cancer. Less than one percent of all cancers arise from duodenum. This cancer can occur in anybody, however, it is most commonly seen above 60 years of age.

Some risk factors increasing the likelihood for this cancer are:

1. Age
   As already mentioned, these cancers are most commonly seen above 60 years i.e. increasing incidence with increasing age.
   
   
2. Inflammatory bowel disease
   These are the disorders of the gut. They are of two main types, Ulcerative colitis, and Crohn’s disease. They cause chronic inflammation in the gut and have a waxing waning course. They predispose to cancers of both the small intestine and large intestine.
   
   
3. Some kinds of genetic disorders or hereditary syndromes 
   Lynch syndrome, Peutz Jeghers syndrome. Families and persons suffering from these syndromes have an occurrence of cancer at a younger age and more than one kind of cancer can be seen.
   
   
4. Alcohol intake
   Alcohol also predisposes to cancers of the small intestine and large intestine.
   
   
5. Diet where red meat and proceeded meat intake is high.

Signs and symptoms

Initial symptoms can be nonspecific and vague- making early diagnosis difficult. Symptoms of duodenal cancer will depend on the part of duodenum involved. So if cancer is starting from part close to the stomach-it causes obstruction resulting in vomiting. Tumorous growth in other parts also causes obstruction but if it close to stomach, these symptoms are much common.

If it starts from part close to bile duct, it leads to bile duct obstruction causing jaundice.

If there is ulcer in cancer there could be bleeding and pain. Bleeding manifests more commonly as anemia and weakness.

If duodenal cancer has spread to other organs then presentation could be specific organ involvement like liver dysfunction in case of liver involvement.

Weight loss, weakness, abdominal pain and anemia are common symptoms. Having these symptoms does not mean necessarily that patient has duodenal cancer. There are few other intestinal disorders causing these symptoms. Irritable bowel syndrome, inflammatory bowel disease, tuberculosis of intestine can cause such manifestations too.

Investigation:
Once your treating doctor suspects the presence of duodenal cancer based on the signs and symptoms, he or she will order certain investigations to confirm the diagnosis and to see the extent of the disease. These include:

1. Blood tests 
   If there is blood loss from tumor/cancer: it gives rise to anemia. Also there are certain chemicals which are released in blood from cancer. Levels of these can help in diagnosis and later on monitoring for treatment response. These chemicals are called as tumor markers. In duodenal cancer level of carcinoembryonic antigen (CEA) - a tumor marker can be raised.
   
   
2. Upper gastrointestinal endoscopy
   During this procedure, a thin, flexible tube called an endoscope is inserted through a person's mouth followed by throat. It then passes through the stomach and into the duodenum. The endoscope has a light and camera on the end, which allow the doctor to see and photograph problematic areas.
   
   
3. Biopsy
   If in an endoscope, a lesion is detected- a biopsy is taken. This provides us with a tissue sample. This sample is later examined under a microscope for the presence of cancer.
   
   
4. Imaging 
   Scan using CT scan or PETCT scan is done to see if the disease has spread to any other organ. Duodenal cancer can spread to the liver, lungs, and lymph nodes. Higher is the extent of disease, worse is the chance of cure.
   
   
5. Advanced molecular tests 
   These tests performed on the biopsy specimen to detect additional targets that can be used for the treatment. Treatment depends on the extent of the disease. If localized disease, surgery is done to remove part of intestine containing the tumor. Surgery to remove cancers are generally more extensive than non-cancer surgeries. This resected specimen is sent to lab for detailed analysis.
   Based on these findings some times chemotherapy is administered after surgery to prevent cancer from recurring.
   In metastatic disease, a mainstay of treatment is chemotherapy.
   Duodenal cancer are very rare. Cancer occurring from large intestines or colon are much more common than small intestine. Hence small intestinal cancer including duodenal cancers are treated on the line of colon cancers