Expert: John C. M.D. - 2/9/2001

Question
My cousin was recently diagnosed with colon cancer metastasized to both lobes of the liver,  9 lymph nodes, and to the lung. It is described as a "very aggressive" cancer. What is life expectancy assuming no treatment other than surgical removal of the primary tumor? With standard chemo?

When colon cancer is on both sides of the family (mom, dad and now, paternal first cousin), what are the cancer risk stats?

Is an annual colonoscopy (age 48) precaution enough?

Many thanks.

Answer
There are two major inherited colorectal cancer syndromes associated with increased risk of colon cancer: 1) adenomatous polyposis coli(APC) and 2) Hereditary nonpolyposis colon cancer(HNPCC).  
APC is characterized by early onset of polyps in the colon during the first decade of life and by age 20 most patients with APC have hundreds of polyps in their colon. Untreated all patients with the disease will develop colon cancer.  Children of people with APC have a 50% chance of getting the syndrome.
HNPCC patients have an 80% lifetime risk of colorectal cancer.  Unlike APC patients, they do not develop hundreds of colon polyps early in life. We suspect someone has HNPCC when they don't have APC and all of the following are true on one side of the family:

(1) 1 family member diagnosed with colorectal cancer before age 50
(2) 2 generations affected by colorectal cancer
(3) 3 affected relatives, 1 of them a first-degree relative of the other 2

Someone without a family history that suggests APC or HNPCC, but with some relatives having colorectal cancer do have a two to 6 fold increased risk of colorectal cancer over the general population.

One recommendation for patients with HNPCC in the family has been to begin yearly screening colonoscopies between the ages of 20 and 30 years of age.

One recommendation for patients with a strong family history of colorectal cancer but without APC or HNPCC has been to begin every 5 year colonoscopies at the age of 40.

These recommendations vary greatly and depend on gathering an accurate family history and in some cases depends on genetic testing.  I would recommend that you discuss your situation with your family doctor and be referred to an expert in colorectal cancer for screening recommendations.