Aggressive Neuroendocrine Tumors of the Colon and Rectum

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Aggressive neuroendocrine tumors of the colon and rectum account for about four percent of all colorectal cancers. The average age at diagnosis is 65, and they seem to favor the right (ascending) colon. 

Aggressive vs. Indolent Neuroendocrine Tumors

Neuroendocrine tumors are divided into two main categories: aggressive and indolent. Large cell and small cell neuroendocrine tumors are considered aggressive, prone to growing rapidly and invading other tissues.

Carcinoid tumors are considered indolent - slower growing and less invasive.

Survival Rates for Aggressive Neuroendocrine Tumors

Aggressive neuroendocrine tumors are usually diagnosed at more advanced stages - a circumstance that generally results in a poor prognosis. Research published in the journal Diseases of the Colon and Rectum determined survival rates for 39 people diagnosed with aggressive neuroendocrine tumors. Of these 39 people, 58 percent were alive six months after their diagnosis, 15 percent were alive three years after their diagnosis, and 6 percent were alive five years after their diagnosis.

However, there are a couple of important caveats to consider. First, a sample size of 39 is very small, so don't put too much faith in those numbers. Also, the study found that survival was associated with tumor stage but not with other things like age, sex, or tumor location. Most of the study participants (79 percent) were diagnosed with stage 3 or 4 tumors.

In general, the later colorectal cancer is discovered, the harder it is to treat.

Ensuring the Proper Diagnosis of Neuroendocrine Tumors

Research shows that aggressive neuroendocrine tumors are often initially misdiagnosed as carcinoid tumors. That's an unfortunate mistake since carcinoids grow slowly and seldom spread.

If you've been told you have a carcinoid tumor, make sure an experienced pathologist agrees with your diagnosis. Doing so will require that you ask your doctor some key questions:

  1. Has a pathologist participated in the final read of my tumor specimen?
  2. Is the pathologist experienced in differentiating between aggressive and indolent neuroendocrine tumors?
  3. Did the pathologist express any doubts about my diagnosis?

If the answers aren't yes, yes, and no (or real close to that), your medical team has more work to do before providing you with a definitive diagnosis.

To learn about other forms of colon cancer, including the most common form (adenocarcinoma), please read the article Types of Colon Cancer.

Other Types of Colorectal Cancer:


  1. Onoda, N. and Kobayashi, H. "Neuroendocrine Carcinoma of the Sigmoid Colon: Report of a Case." Surgery Today 29.10 (Sep. 1999): 1079-1082.
  2. Saclarieds, T.J. and Szeluga, D. "Neuroendocrine Cancers of the Colon and Rectum. Results of a Ten-Year Experience." Diseases of the Colon and Rectum 37.7 (Jul. 1994): 635-642. [].

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