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Hereditary Colorectal Cancer Changes Screening and Treatment Plans

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Hereditary Colorectal Cancer Changes Screening and Treatment Plans

The American Cancer Society (ACS) estimates that there will be over 145,000[1] new cases of colorectal cancer diagnosed this year, making it the fourth most common cancer[2]. It is also the third leading cause of cancer-related deaths, with an estimated 51,020 deaths in 2019 caused by colorectal cancer. Unfortunately, only 15-20% of hereditary colon cancer is identified each year, leaving thousands of unaffected relatives at risk when preventative measures are both simple and accessible[3].

Thankfully, early detection and screening is easily accessible and has been shown to reduce morbidity and mortality. According to the National Cancer Institute’s SEER database, the five year survival rates for patients diagnosed with stage I colon or rectal cancer is 92% and 88% respectively[4]. If left undetected, the survival rates drop exponentially, with rates as low as 12% and 13% respectively for stage IV metastatic colon and rectal cancers. Although ACS recommends that people at an average risk of developing colorectal cancer receive a colonoscopy every 10 years, patients with an elevated risk of colorectal cancer should screen more frequently and starting at an earlier age.

Identifying whether or not a patient has hereditary colon cancer, by using a hereditary cancer panel such as Myriad myRisk® may change both screening and treatment plans. Instead of following up every one, three, and five years with colonoscopies, NCCN management guidelines for the treatment of Lynch syndrome recommend colonoscopies every 1-2 years after surgery for patients with hereditary colorectal cancer due to the increased risk of a second primary cancer and the accelerated rate at which polyps progress to malignant disease. The expansion of the NCCN Familial High-Risk Colorectal guidelines to include the PREMM5 model has made identifying patients who meet genetic testing criteria easier than ever as all newly diagnosed patients with a PREMM score of 2.5% or higher now meet testing criteria.

Patients who have been diagnosed with Lynch syndrome are also more likely to comply with the increased surveillance recommendations, as 73% of patients with Lynch Syndrome undergo their recommended colonoscopies versus only 16% of patients with familial risk[5]. Surgical considerations such as a total colectomy, when appropriate, can reduce metachronous colorectal cancer risk by up to 100%[6].  Thousands of patients are currently being undermanaged for their hereditary increased risk of colorectal cancers, but germline genetic testing via the myRisk hereditary cancer panel can give you the most personalized risk, and management plan, to effectively screen your patients.

How do you know if your patient meets recommended medical guidelines for testing? Below are some red flags that a patient could have Lynch Syndrome:

  • Patient has been diagnosed with colorectal or endometrial cancer before age 64
  • A first or second degree relative with colorectal or endometrial cancer before age 50
  • Two or more relatives with a Lynch Syndrome cancer, one of whom was diagnosed before age 50
  • Three or more relatives with a Lynch Syndrome cancer at any age
  • Colorectal cancer with MSI-high histology before age 60
  • Patient has two or more Lynch Syndrome-related cancers at any age
  • Patient has a Lynch Syndrome cancer and one or more relatives with a Lynch Syndrome cancer
  • A previously identified Lynch Syndrome or MAP mutation within the family
  • A PREMM5 score greater than or equal to 2.5%

[1] https://www.cancer.org/cancer/colon-rectal-cancer/about/key-statistics.html

[2] https://seer.cancer.gov/statfacts/html/colorect.html

[3] Based on an internal analysis

[4] https://www.cancer.org/cancer/colon-rectal-cancer/detection-diagnosis-staging/survival-rates.html

[5] Halbert CH, et al. Colon cancer screening practices following genetic testing for hereditary nonpolyposis cancer (HNPCC) mutations. Arch Int Med, 2004;164:1881-1887.

[6] Parry et al. Metachronous colorectal cancer risk for mismatch repair gene mutation carriers: the advantage of more extensive colon surgery. Gut. 2011; Jul;60(7):950-7.