“This is a time when we should concentrate our efforts on picking the low-hanging fruit,” Dr. Patel advised. She explained that this will entail a three-pronged approach: doing a better job of promptly evaluating potential symptoms of CRC, casting a wider net in search of patients with a hereditary cancer syndrome, and initiating earlier screening, especially in high-risk patients – a category that she said should include all African-Americans.
Prompt evaluation of symptoms
In one major study, the average time from symptom onset – bleeding, unexplained abdominal pain, changes in bowel habits, and/or iron deficiency – to diagnosis of CRC was 217 days in those with early-onset CRC, compared with 29.5 days in patients age 50 or older.
This huge disparity in time to diagnosis occurs largely because physicians typically assume that scant blood present in the stool of younger patients is due to hemorrhoids. Also frequently overlooked is the fact that the presence of hemorrhoids on physical examination can obscure an upstream malignant lesion.
“The initial plan is often to treat assumed benign pathology and only if symptoms persist to consider other causes,” Dr. Patel noted. That practice, she said, has to change: “The tools that we rely on in the clinic for this particular complaint – history and physical examination – are just not as reliable as we need them to be.”
Assessing for increased genetic/familial risk
The best estimate is that 16%-25% of early-onset CRC may be due to a high- or moderate-penetrance genetic mutation. Another 35% or so of cases are associated with a positive family history for CRC without a defined genetic condition.
In a 2011 study a mere 1.2% of Americans carrying a Lynch mutation were aware of it. “I suspect today it’s still less than 10%. We’re still not doing a very good job of identifying high-risk patients,” Dr. Patel said.
The National Comprehensive Cancer Network has published a guideline for assessment of genetic/familial high risk for CRC, but it’s far too complex and detailed for practical use in a busy primary care practice, in her view.
“You don’t have to remember all the detailed branching algorithms and criteria in the NCCN guideline. I propose a gut check. Increased risk boils down to three key points: any patient with onset of advanced neoplasia before age 50, or a personal history of multiple cancers, whether synchronous or metachronous, or with a strong family history of cancer on one side of the family should be sent on for a detailed risk assessment,” she said.
Similarly, don’t sweat trying to remember all the types of cancer associated with Lynch syndrome.
“We’re learning that the true answer is that it could be any kind of cancer,” Dr. Patel said.
It’s worth bearing in mind, however, that just because a patient doesn’t have a positive family history doesn’t mean that a hereditary cancer syndrome can be ruled out. Incomplete penetrance is characteristic of all of these hereditary syndromes. Indeed, 2 out of 10 patients with Lynch syndrome will never develop CRC.
Multiple gastroenterology societies now recommend routine PCR screening of all colon cancers for microsatellite instability markers – the hallmark of Lynch syndrome tumors – even if the cancer occurs in an 88-year-old. And if the screen is positive, genetic testing is appropriate. The University of Colorado is among a growing number of medical centers that have implemented this policy.
Dr. Patel noted that the American Cancer Society characterized its start-screening-at-45 guideline for average-risk patients as “conditional” rather than a “strong” recommendation. She advised applying it without reservation – and in some instances even starting at age 40 – for three groups clearly at high risk for early-onset CRC: African Americans, patients with a family history of CRC, and those with a family history of advanced adenoma, such as a tubular adenoma, which if not removed has an 80% chance of progressing to cancer.
She reported having no financial conflicts regarding her presentation.