Stool-Based Screening Improves Long-term CRC Survival

Megan Brooks

March 01, 2022

A recent population-based study from Korea links fecal immunochemical test (FIT) screening to improved long-term survival after a colorectal cancer (CRC) diagnosis.

But timing matters, with the best survival outcomes seen in patients who completed the noninvasive stool-based screening within 12 months before their CRC diagnosis, the authors find.

The study was published online January 31 in the International Journal of Cancer.

Since 2004, the Korea National Cancer Screening Program (KNCSP) has provided FIT-based CRC screening for adults aged 50 and older, followed by colonoscopy or double-contrast barium enema to confirm CRC for patients with abnormal FIT results.

Yet, studies evaluating the long-term survival effects of population-level FIT screening remain "surprisingly limited in both Korea and Asia," the authors point out.

The researchers investigated the effect of FIT screening on long-term survival using the Korea Central Cancer Registry and the KNCSP database, as well as death certificate data.

Among 32,509 adults diagnosed with CRC between 2008 and 2009, 60.4% were never screened (n = 19,624), and 39.6% (n = 12,885) received FIT screening between 2004 and 2009. By the end of 2019, 61.5% patients were alive.

Long-term survival was significantly higher among screened patients compared to patients who were not screened (68.2% vs 57.2%), the study team found.

The risk of dying from CRC was 23% lower among screened patients compared to those never screened (adjusted hazard ratio [HR], 0.77; 95% CI, 0.73 – 0.80).

Patients with FIT-screened localized CRC had the lowest risk of dying from CRC (HR, 0.48; 95% CI, 0.42 – 0.56).

This finding indicates that screening improves the chances of catching the cancer earlier and detecting slow-growing cancers and is associated with a better prognosis compared to symptom-detected cases, the authors say.

Still, the survival advantage persisted in the FIT screened population after controlling for CRC stage. Even patients with distant-stage disease showed a 9% lower risk of CRC death with screening (HR, 0.91; 95% CI, 0.85 – 0.98).

FIT screening interval also appears to be a key factor, with CRC patients screened within 1 year before diagnosis having the highest survival rates.

The risk for CRC-specific death was 30% lower among patients screened within 1 year of their diagnosis (HR, 0.70; 95% CI, 0.66 – 0.74).

The CRC survival rate decreased with an increase in the screening interval, and the risk of CRC-specific death was almost the same in patients who were never screened and those who were screened more than 2 years before their CRC diagnosis, the researchers report.

"Therefore, our results suggest that the best screening interval for CRC screening using FIT is 1 year, which could be extended depending on the national budget and colonoscopy capacity, but the screening interval should not be more than 2 years, as indicated in many screening guidelines and recommendations," they write.

In 2012, the KNCSP revised the FIT screening interval from 2 years to 1 year, which pushed the size of the eligible population from 9.3 million to 15.5 million people.

"Accordingly, even in Korea, where the health care system was relatively well established, colonoscopy capacity was almost reached. Thus, to consider a shorter FIT interval, policymakers also need to carefully consider the colonoscopy capacity in countries and regions, especially those with limited resources," the researchers acknowledge.

The study was supported by a grant-in-aid for cancer research and control from the National Cancer Center of Korea. The authors have disclosed no relevant financial relationships.

Int J Cancer. Published online January 31, 2022. Abstract

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