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Screening for Lynch syndrome less efficient after age 70 to 75 years

Lynch syndrome screening among patients with newly diagnosed colorectal cancer was significantly less efficient in patients after age 70 to 75 years, and ending screening in patients aged older than 80 years may be more reasonable than universal screening, according to research findings published in Annals of Internal Medicine.

According to the researchers, patients with Lynch syndrome (LS) have an 80% risk for colorectal cancer and 60% risk for endometrial cancer in their lifetime, along with elevated risks for prostate, stomach, ovarian, small intestine, hepatobiliary tract, urinary tract and brain cancers.

“Over the past 2 decades, the LS screening strategy has evolved from use of clinical criteria only to use of the Bethesda guidelines and then to universal screening,” Dan Li, MD, of Kaiser Permanente Northern California in Santa Clara and Oakland, and colleagues wrote. “The universal strategy advocates screening all patients with newly diagnosed [colorectal cancer] for LS and has been shown to be the most sensitive method.”

“Prior studies have shown that the most cost-effective screening method is immunohistochemistry of [colorectal cancer] tumors followed by genetic testing if indicated,” they continued. “Although the universal screening strategy is widely accepted, its diagnostic yield and cost-effectiveness among elderly patients, particularly those older than 70 years, have not been well investigated.”

Researchers conducted a retrospective cohort study among members of Kaiser Permanente Northern California to evaluate the performance of universal LS screening among patients with newly diagnosed colorectal cancer from April 1, 2011, to Dec. 31, 2016. Kaiser Permanente Northern California established a population-based universal screening protocol for LS in April 2011 that called for surgical specimens of all newly diagnosed colorectal cancer tumors to be tested for mismatch repair protein expression by immunohistochemistry. Patients with abnormal results were contacted by the genetics department and offered further genetic testing to determine LS diagnosis.

During the study period, 3,891 patients underwent LS screening. After testing, 63 patients (1.62%) received an LS diagnosis through universal screening; five (7.9%) were detected after 70 years of age and one (1.6%) after 80 years of age.

Among patients with LS, 58 were identified in patients diagnosed with colorectal cancer before or at 70 years (diagnostic yield, 1.49%; 95% CI, 1.13-1.92), 60 were identified in those diagnosed with colorectal cancer before or at 75 years (diagnostic yield, 1.54%; 95% CI, 1.18-1.98) and 62 LS cases were identified in patients diagnosed with colorectal cancer before or at 80 years (diagnostic yield, 1.59%; 95% CI, 1.22-2.04).

By setting 75 years as the upper age limit for LS screening researchers found that three of 63 LS patients (4.8%) were missed, but 1,053 (27.1%) fewer colorectal cancer cases required tumor mismatch repair immunohistochemistry testing. Setting 80 years as the upper age limit for LS screening missed one LS patient out of 63 (1.6%) and led to 668 (17.2%) fewer cases that required mismatch repair immunohistochemistry testing.

“The incremental diagnostic yield decreased substantially after age 70 to 75 years,” Li and colleagues wrote. “Because LS is rare after age 80 years, the efficiency of universal screening is very low, and stopping reflex screening in this age group may be reasonable, particularly in resource-limited settings.” – by Erin Michael

Disclosures: Li reports no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.