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Understanding Your Type of Colorectal Cancer

A kind of cancer called adenocarcinoma accounts for more than 95% of colorectal cancers. There are other rare types of cancer that can be found in the colon and rectum:

  • Gastrointestinal stromal tumors

  • Lymphomas

  • Carcinoids

Adenocarcinoma

Adenocarcinomas are tumors that start in cells with glandular properties, or cells that secrete. Adeno means gland. They can form in a lot of different organs, such as the colon, rectum, lung, or breast. In colorectal adenocarcinoma, early tumors start as small adenomatous polyps that continue to grow and then turn into malignant tumors.

Rare types of colorectal cancer

There are other types of tumors that can develop in your colon and rectum. They are described only briefly here because they are rare forms of colorectal cancer.

  • Gastrointestinal stromal tumors. These are tumors that start in specialized cells in the wall of the colon called the interstitial cells of Cajal. They can be benign at first. Many, though, turn into cancer. When they do, they are called sarcomas. Surgery is the usual treatment for tumors that haven't spread.

  • Lymphomas. A lymphoma is a cancer that typically starts in a lymph node, which is part of your immune system. However, it can start in your colon, rectum, or other organs. There are different kinds of lymphomas.

  • Carcinoids. These tumors start in special hormone producing cells in your intestine. Often they cause no symptoms at first. Surgery is the normal treatment for most tumors.