What is a Mucinous Adenocarcinoma of the Colon and Rectum?

It's unclear whether this subtype of adenocarcinoma has a worse prognosis.

Colorectal cancer comes in many forms, including adenocarcinoma, leiomyosarcoma, lymphoma, melanoma, and neuroendocrine tumors.

Classic adenocarcinoma is the most common type of colorectal cancer, comprising more than 95 percent of all colorectal cancer, according to the American Cancer Society.

Then there are two less common subtypes of adenocarcinoma: 

    This article discusses mucinous adenocarcinoma.

    First, What is an Adenocarcinoma?

    "Adeno-" is a prefix that means "gland." In general, glands secrete things and are classified as endocrine or exocrine. Endocrine glands secrete things into the bloodstream, like hormones. Exocrine glands secrete things that go outside of the body, like mucus and sweat.

    A carcinoma is a malignant tumor that starts in epithelial tissue. Put the two words together and you get "adenocarcinoma," which means a malignant tumor in epithelial tissue, specifically in a gland.

    What is a Mucinous Adenocarcinoma?

    The term "mucinous" means that something has a lot of mucin, which is made by glands in the colon to help lubricate it. Adenocarcinomas that make a lot of mucin are called mucinous adenocarcinomas, and they account for about 10 percent of all colorectal adenocarcinomas. They are also sometimes called colloid adenocarcinomas.

    A pathologist can diagnose a mucinous adenocarcinoma versus a regular adenocarcinoma by examining a piece or sample of the tumor (this is called a biopsy) under the microscope.

    The mucin, which makes up 50 percent or more of the tumor in colorectal mucinous adenocarcinomas, helps the tumor extend, as the mucin dissects through the wall of the tumor.

    Scientists think that the presence of mucin allows cancer cells to spread faster. As a result, mucinous adenocarcinomas are sometimes considered more aggressive than regular or classic adenocarcinomas. Although, this is still highly debated and likely depends on a number of other factors related to the tumor.

    It interesting to note too, that mucinous adenocarcinomas in the colon and rectum are associated with a younger age, females, and being located on the right side of the colon. 

    A Word From Verywell

    While some research has found that people with mucinous adenocarcinoma have more advanced tumor stages and reduced survival (less likely to live) when compared to people with classic adenocarcinoma, other research studies do not show this. So at this time, the true impact of a mucinous adenocarcinoma versus a regular adenocarcinoma on a person's chance of recovering from cancer is unclear at this time. 

    Sources:

    American Cancer Society. (January 2016). Types of cancer in the colon and rectum.

    Compton, CC. Pathology and prognostic determinants of colorectal cancer. In: UpToDate, Tanabe KK (Ed), UpToDate, Waltham, MA.

    Nitsche U et al. Mucinous and signet-ring cell colorectal cancers differ from classical adenocarcinomas in tumor biology and prognosisAnn Surg. 2013 Nov;258(5):775-83.

    Verhulst J, Ferdinande L, Demetter P, Ceelen W. Mucinous subtype as prognostic factor in colorectal cancer: a systematic review and meta-analysis. .J Clin Pathol. 2012 May;65(5):381-8.

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