COLARIS^® Case A

The patient is a woman diagnosed with colon cancer at the age of 42. She has no adenomas and no family history of any HNPCC-related cancers. This patient pursued Comprehensive COLARIS^® and Reflex MSH6 Analysis due to her diagnosis of early onset colon cancer. The Myriad Mutation Prevalence Table estimated a 9.1% chance for this patient to test positive for an MLH1 or MSH2 mutation. However, no mutation was detected by genetic testing.

Genetic Evaluation

• Based on the no mutation detected result for Comprehensive COLARIS^® and Reflex MSH6 Analysis, the likelihood that this patient has HNPCC has been reduced. The negative result leaves us without an explanation for the patient's diagnosis of early onset colon cancer, and her medical management must be based on her clinical history.

• The patient does not have a strong family history of HNPCC-associated cancers, which leads to a low suspicion of an undetectable MLH1, MSH2 or MSH6 mutation.

• Tumor tissue analysis [i.e. microsatellite instability testing (MSI) or immunohistochemistry testing (IHC)] might be appropriate to screen for rarer causes of HNPCC. Please note that MSI and IHC are not diagnostic for HNPCC but they may help to direct medical management and further genetic testing.

• Further evaluation by a genetics specialist might be appropriate.

Medical Management

For patient:

• Given her personal history of colon cancer, the patient will continue to have an increased risk of a second colon cancer, as compared to other women her age.

• Colonoscopy is recommended within one year following the colon cancer diagnosis. If this exam is normal, it should be repeated in three years and, if normal, repeated every five years.

With regard to at-risk relatives:

• Colonoscopy is appropriate beginning 10 years prior to the earliest colon cancer diagnosis in the family or age 40, which ever is first. Since this example illustrates a patient with colon cancer at age 42 years, this would mean colon cancer screening should begin at age 32 years in this family (e.g., for this patient's siblings and children).

• Genetic testing would not be recommended for this patient's relatives, since no mutation was detected in her.

References:

1. American Cancer Society Guidelines on Screening and Surveillance for the Early Detection of Colorectal Adenomas and Cancer – Women and Men at Increased Risk or High Risk. Available at www.cancer.org. Accessed September 14, 2005.
2. NCCN Clinical Practice Guidelines in Oncology. Colon Cancer, v. 4.2005. Available at www.nccn.org . Accessed September 14, 2005.
3. Winawer S, Fletcher R, Rex D, et al. (2003) Colorectal cancer screening and surveillance: clinical guidelines and rationale – update based on new evidence. Gastroenterology. 124:544-60.

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