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A study released Tuesday — led in part by UC San Diego School of Medicine researchers — found waiting between abnormal results from a self-administered colorectal cancer screening and a colonoscopy increases the risk of being diagnosed with cancer.

Colorectal cancer is the second most common cause of cancer-related mortality among men and women in the United States, according to the American Cancer Society. At-home tests, which measure blood in stool as a potential marker for colon cancer, are often used for colorectal cancer screening.

Usage of these home tests has increased during the COVID-19 pandemic as people try to avoid clinical visits. However, effectiveness of these screening tools, along with all colon cancer screenings, requires a follow-up colonoscopy if an abnormal test result occurs. The problem is that experts say current follow-up rates are low.

The study, led by researchers at UCSD School of Medicine, Veterans Affairs San Diego Healthcare System, Veterans Affairs Greater Los Angeles Healthcare System and UCLA, found delayed time between abnormal stool-based screening and subsequent colonoscopy was associated with an increased risk of a cancer diagnosis and death from colorectal cancer.

Published in the Feb. 2 online edition of Gastroenterology, the study found those who delayed a colonoscopy by more than a year after an abnormal screening test result were at an increased risk of being diagnosed with colorectal cancer. The odds of being diagnosed with late-stage colon cancer increased at 16 months by approximately 33%.

“Many colon cancers are asymptomatic and can be growing without the patient even knowing,” said Dr. Samir Gupta, corresponding author of the study and professor of medicine in the division of gastroenterology at UCSD School of Medicine and VASDHS. “That is why it is so important to screen. But as our study shows, it is also critical to follow up with a colonoscopy if the screening result is abnormal.”

Early detection means less invasive treatments and better outcomes. When detected early, patients have a 90% survival rate with a low risk of recurrence. Late-stage colorectal cancer means more invasive and complex treatment with less than a 15% survival rate.

The national study involved 204,733 veterans ages 50 to 75 with an abnormal screening test. A limitation of the study was a high proportion of men; 5,453 women were included.

“There are no national standards or mandates to guide patients, providers or health care systems on the clinically acceptable period of time between abnormal screening and colonoscopy,” said Dr. Folasade May, senior author of the study and assistant professor of medicine at UCLA. “We hope our findings will inform national standards for appropriate time intervals and interventions to improve timely colonoscopies and colorectal cancer outcomes.”

A family history, smoking and poor diet are significant risk factors of colon cancer. Symptoms include rectal bleeding, low-iron anemia, a change in bowel habits and unexplained weight loss.

In 2018, the American Cancer Society updated guidelines for colorectal cancer screening. It is now recommended that those age 45 with an average risk of colon cancer begin regular screenings. Previously, the guideline recommended screening begin at age 50 for people at average risk.

“In general, prevention and early detection efforts have substantially dropped death rates in the United States. However, the pandemic has resulted in many people missing cancer screenings or not doing follow-up colonoscopies after abnormal at-home screenings,” Gupta said. “We strongly encourage patients to schedule an appointment if they receive an abnormal screening test. Our hospital and clinical settings are following all COVID-19 safety guidelines. Hesitancy to follow up on your health care could have fatal consequences.”

–City News Service

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