A few neuroendocrine tumors found in the gastrointestinal tract are made of fast-growing, poorly differentiated cancer cells, and respond to different treatments than those used for carcinoid tumors.

Despite their rare occurrence in the gastrointestinal tract, doctors at Memorial Sloan Kettering have significant experience in diagnosing and treating patients with the following rare types of gastrointestinal neuroendocrine carcinomas:

Large Cell Neuroendocrine Carcinoma

This fast-growing type of cancer represents less than 1 percent of all gastrointestinal cancers.

Small Cell Carcinoma

This is another aggressive type of neuroendocrine tumor that accounts for between 0.1 percent to 1 percent of all gastrointestinal tumors.

Diagnosis

The following tests may be performed to confirm a diagnosis of large cell neuroendocrine carcinoma or small cell carcinoma. These tests also may help determine the exact location and size of the tumor, if it has spread to other organs, and whether it can be surgically removed. Gastrointestinal small cell carcinoma and large cell carcinoma are usually diagnosed at an advanced stage, after they have spread to the lymph nodes or other organs.

• Biopsy
  A small sample of the tumor may be obtained for examination under a microscope using either a thin needle (fine-needle aspiration biopsy) or a wider needle (core biopsy).
• CT Scans
  This type of imaging test provides a three-dimensional picture of the inside of the body and is often used to determine whether the tumor has spread to the liver or nearby lymph nodes. Sometimes a dye is injected into the organ to help provide better detail.
• PET Scans
  A small amount of radionuclide is given intravenously and is absorbed by the organs to be imaged. The radionuclide produces energy that is detected by a scanner. This type of imaging test is helpful in diagnosing more aggressive types of neuroendocrine tumors.

Treatment

Because small cell and large cell neuroendocrine carcinomas of the gastrointestinal tract are usually found at an advanced stage, treatment often begins with a combination of platinum-based chemotherapy drugs. In the rare instances in which these aggressive tumors are localized, radiation and/or surgery may be recommended in addition to chemotherapy.