Guidelines for Colorectal Cancer Screening and the Recent Evidence Behind Them
Nazia Hasan, MD MPH
Faculty peer reviewed
For most residents, screening for colorectal cancer (CRC) may seem as established as that for breast and cervical cancer. In reality, the use of CRC screening has only recently approached that of screening for those other malignancies. We have seen recently changes to the CRC screening guidelines last published by The American College of Gastroenterology in 2000. The updated screening guidelines for colorectal cancer became available in the March 2009 issue of The American Journal of Gastroenterology.
Along with changes in the timing and modalities used for CRC screening, the goal of screening has also been transformed. Screening efforts have shifted focus to favor cancer prevention tests over cancer detection tests. This blog series aims to review the updated guidelines for CRC screening illustrated through cases.
A 35 year old female with no significant past medical history presents for routine health maintenance. She endorses her father was diagnosed with colon cancer at age 45.
At what age should this patient be offered a screening colonoscopy?
As in the previous case, we must determine if this pt is at high risk with the following questions:
1. Does the patient have a personal history of CRC or an adenomatous polyp?
2. Does the patient have an illness (e.g., IBD) that predisposes him/her to CRC?
3. Does the patient have a family history of CRC or an adenomatous polyp? If so, how many relatives were involved, was it a first-degree relative (parent, sibling, or child), and at what age was the cancer or polyp first diagnosed?
In cases with a family history of CRC, updated ACG screening guidelines propose the following:
Patients with a 1st-degree relative with CRC or advanced adenoma* (>1cm, high-grade dysplasia, or villous features) diagnosed at age > 60 years should be screened the same as average risk (colonoscopy every 10 years starting at 50 years; 45 years if African American)- Grade 2B.
Patients with a 1st-degree relative with CRC or advanced adenoma diagnosed at age < 60 years or two 1st-degree relatives diagnosed with CRC at any age should be advised to get screening colonoscopy at age 40 years or 10 years younger than the earliest diagnosis in their family, and repeated every 5 years- Grade 2B.
Patients with one 2nd or 3rd -degree relative with CRC should be screened as an average-risk patient.
*Note that there should a specific history of advanced adenoma in a 1st degree relative at <60 years to alter screening. In other words, small tubular adenomas in family members do not increase the risk of CRC based on evidence that individuals with small tubular adenomas (< 1 cm) and/or low-grade dysplasia themselves are not shown to be at an increased risk for developing CRC.2
Thus, our patient in Case 3 should begin screening now at age 35 and have colonoscopy repeated every 5 years.
Dr. Hasan is a 3rd year internal medicine resident at NYU Medical Center.
Reviewed by Michael Poles MD, Assistant Professor of Medicine, NYU Division of Gastroenterology
1. Rex D, Johnson D, Anderson J, Schoenfeld P, Burke C, Inadomi J (2009). American College of Gastroenterology Guidelines for Colorectal Cancer Screening 2008. Am J Gastroenterology. 104:739-750.
2. Atkin WS , Morson BC , Cuzick J (1992). Long-term risk of colorectal cancer after excision of rectosigmoid adenomas. N Engl J Med. 326: 658 – 662.