High Adenoma Detection Rates Linked to Lower CRC Rates, Worse Survival

Although hospitals with high adenoma detection rates (ADR) significantly reduced the incidence and mortality of postcolonoscopy interval colorectal cancer (CRC), patients diagnosed in these settings paradoxically had worse survival, a study from Taiwan’s national CRC screening program found.¹

This cohort study is published in JAMA Network Open.

In a large fecal immunochemical test-based screening program, high adenoma detection rates lowered interval colorectal cancer incidence and mortality, but not CRC-specific survival. | Image credit: Paul Maguire - stock.adobe.com

“We believe our most notable finding is the worse postcolonoscopy interval CRC survival in the high-ADR group compared with the low-ADR and middle-ADR groups, with survival similar to that of post-FIT [fecal immunochemical test] interval CRC,” wrote the researchers of the study. “This finding suggests a complex interplay between instrumental factors, such as ADR, and the intrinsic biological behavior of cancers, affecting the pattern of interval CRCs and their long-term outcomes.”

The FIT is a widely used, noninvasive screening tool for CRC that detects hidden blood in stool, which is an early sign of cancer or advanced precancerous lesions.² Unlike older guaiac-based tests, FIT offers improved sensitivity and specificity, requires no dietary restrictions, and is easy for patients to complete at home.

The researchers analyzed data from participants aged 50 to 74 years who completed at least 1 FIT between January 1, 2004, and December 31, 2012.¹ One consisted of individuals with a negative FIT result and another comprising individuals with a positive FIT result followed by a negative colonoscopy. Interval CRCs were identified and followed through December 31, 2019.

Additionally, participants were further stratified by hospital-level ADR, categorized as low (less than 40%), middle (40% to 64%), or high (greater than or equal to 65%). The study’s primary outcomes were the incidence, CRC-specific mortality, and survival associated with interval CRCs, specifically post-FIT and postcolonoscopy interval CRCs.

Data analysis was performed over a 15-year period from January 2004 to December 2019.

The study identified 4018 cases of interval CRC among 15,386 total CRC diagnoses, with 2782 (18.1%) occurring after a negative FIT result and 1236 (8.1%) following a negative colonoscopy after a positive FIT. The incidence of postcolonoscopy interval CRC (0.75 [95% CI, 0.71-0.79] per 1000 person-years) was significantly higher than post-FIT interval (0.09 [95% CI, 0.09-0.10] per 1000 person-years), as was CRC-specific mortality (0.12 [95% CI, 0.11-0.14] per 1000 person-years vs. 0.02 [95% CI, 0.02-0.03] per 1000 person-years).

Adjusted hazard ratios (AHRs) confirmed these differences for incidence (AHR, 7.06; 95% CI, 6.35-7.57) and for mortality (AHR, 5.04; 95% CI, 4.33-5.85).

Moreover, a higher hospital-level ADR was associated with reduced interval CRC incidence and mortality for the high-ADR group (AHR, 0.26; 95% CI, 0.20-0.36) vs. the low-ADR group (AHR, 0.28; 95% CI, 0.19-0.4), respectively. However, among patients with postcolonoscopy interval CRC, CRC-specific mortality was higher in the high-ADR group compared with the low-ADR group (AHR, 1.89; 95% CI, 1.04-3.43), suggesting that improvements in detection may not translate to better survival outcomes.

However, the researchers acknowledged some limitations. ADR was measured at the hospital level, which may have masked variation among individual endoscopists. Differences in polyp characteristics across ADR groups also suggest possible case-mix effects. Follow-up time may have been too short to capture all postcolonoscopy interval CRCs, especially for late enrollees. Finally, follow-up start dates differed between groups, though most colonoscopies occurred within 6 months of a positive FIT.

“The worse survival of postcolonoscopy interval CRC in high-ADR settings suggests a ceiling effect for current colonoscopic techniques and quality assurance,” wrote the researchers. “It also highlights the possible interplay between instrumental and biological factors that might require innovative preventive and therapeutic interventions.”

References

1. Hsu W, Ladabaum U, Su C, et al. Interval colorectal cancers in a fecal immunochemical test–based screening program. JAMA Netw Open. 2025;8(7):e2523441. doi:10.1001/jamanetworkopen.2025.23441

2. McNulty R. FIT outperforms blood-based cfDNA test in detecting precancerous colorectal lesions. AJMC^®. May 31, 2025. Accessed July 31, 2025. https://www.ajmc.com/view/fit-outperforms-blood-based-cfdna-test-in-detecting-precancerous-colorectal-lesions