With advancements in technology and science, we have several screening options to detect colorectal cancer, and the American Cancer Society's 2018 colorectal cancer screening recommendations—lowering the age to 45 for average risk patients—are a welcome update that will help guide the general population. Physicians should also look at this update as a reminder to review the newest advancements to help assess a patient's individual risk for disease.
Traditional risk factors remain important, including family history of colon cancer or history of colon polyps. Recognizing patterns of cancer history could be indicative of hereditary cancer syndrome such as Lynch syndrome, also called hereditary nonpolyposis colorectal cancer, which has elevated risk for colon, uterine, and ovarian cancer.
An emerging area of risk assessment, in the era of precision medicine, involves the use of a genetic risk score (GRS). In 2016, NorthShore University HealthSystem (NorthShore) launched a clinical trial to investigate the GRS test to predict the risk of colorectal cancer in the primary care setting. This test identifies a person's genetic predisposition for developing certain inheritable forms of cancer. It is a unique genetic test that identifies variations in DNA called single nucleotide polymorphisms (SNPs) in patient blood samples. Since most genetic risk is not explained by traditional inherited cancer syndromes such as Lynch syndrome, the GRS test helps to further understand the genetic component of risk.
The genetic risk score given to patients is a weighted sum of SNPs in a patient's DNA as they relate to a particular condition (in this case colon cancer). Every man and woman who would undergo this testing would likely have at least a few of the cancer risk-associated SNPs. Average population risk is equal to a genetic risk score of 1.0 for each cancer. Individuals with a GRS above 1.0 are at higher inherited risk for that cancer, and individuals with a GRS below 1.0 are at lower inherited risk for that cancer. This has the potential to be very valuable information for personalizing cancer screening plans.
For some patients, knowledge about their family history is incomplete or is not available at all, so they might not know where to start when seeking out the best screening options for them. In cases such as this, the GRS test could help patients learn about their inheritable risk. Even when family history is known, there can be considerable variability as to when and if an individual will develop cancer. The GRS can help fill in gaps of knowledge regarding risk.
As many physicians know, colorectal cancer screening has a reputation of being unpleasant, causing people to avoid it. Avoiding screenings is potentially deadly, so discussing all the options with your patients is a good first step. The more knowledge patients have about the different screening choices, the more likely they are to understand their risk and the importance of screening. A helpful guide on all screening options can be found in the American Cancer Society Guideline for Colorectal Cancer Screening: A Summary for Clinicians.
The earlier screening recommendation from the American Cancer Society is an important update that will save lives, as we are seeing a trend of younger colon cancer diagnoses. However, we must continue to ensure that each patient receives the personalized care and screening they need. Learning about an individual's family history, incorporating the latest risk assessment tools, working with them to decide on the best screening option, and putting the patient first allows the patient to have more information and make the best decision on their screening options.
PETER J. HULICK, MD, MMSC, is Director of the Center for Personalized Medicine, NorthShore University HealthSystem.