Investigating the Incidentals

ACRIN study assesses the extracolonic findings of the National CT Colonography Trial.investigating incidentals

Despite the fact that colorectal cancer (CRC) is largely preventable through routine screening, approximately one-third of eligible adults age 50 and older do not undergo screening.

As demonstrated by several large-scale clinical trials, including the National CT Colonography Trial (ACRIN 6664), computed tomography colonography (CTC) is comparable to standard colonoscopy in its ability to accurately detect cancer and precancerous polyps and could serve as an initial screening exam for CRC.1incidental finding 2

CTC has the potential to improve compliance with routine CRC screening.2 Additionally, the literature suggests that, depending on reimbursement rates, CTC may be more cost effective for detecting colonic polyps compared with standard colonoscopy.3,4 Given intense pressure from payers to reduce national health-care expenditures and confirm efficacy, the cost effectiveness of new health-care procedures is under significant scrutiny. One of the reasons the CMS denied coverage for routine CTC was the lack of evidence about the impact of incidental findings outside of the colon, also known as extracolonic findings (ECFs), on patient care and the related costs. Fortunately, researchers have a rich data resource from the ACRIN 6664 trial with which to explore a wide range of CTC-related issues, including the downstream consequences of ECFs currently being investigated by the ACRIN 7151 trial (Incidence and Significance of Extracolonic Findings on CT Colonography: Retrospective Analysis of National CT Colonography Trial Data).

“The ACRIN 7151 trial ... is more comparable than current single-site studies to broad clinical practice." — Hanna M. Zafar, MD, MHS

The trial is led by Principal Investigator Hanna M. Zafar, MD, MHS, assistant professor of radiology at the University of Pennsylvania, and funded by the ACRIN Fund for Innovative Imaging. Researchers are conducting a retrospective chart review of 520 of the 2,531 ACRIN 6664 study participants. The objective of this study is to compare the frequency and cost of follow-up diagnostic imaging, hospitalization, and interventional procedures between participants with the most common potentially clinically significant ECFs and participants with no known ECFs.

As Zafar explains, "The ACRIN 7151 trial will fill several knowledge gaps. It is the first clinical trial to directly evaluate ECFs in a multicenter setting including both academic and private practice settings — so it is more generalizable than current single-site studies to broad clinical practice — and it will compare differences in health-care utilization based upon whether an ECF was reported."incidental finding 1

She goes on to clarify, "Data from the trial can potentially be used to inform cost effectiveness models to better understand the effect of CTC on the incidence of and mortality from CRC. This is important because ECFs were not included in any of the three models used by the Agency for Healthcare Research and Quality (AHRQ) to perform cost-effectiveness analysis for CMS on different methods of CRC screening, including CTC, due to inadequate knowledge about the true harms and benefits of ECFs." Data from the ACRIN 7151 study will help inform colorectal cancer simulation models on the cost effectiveness of CTC when accounting for ECFs. Eventually, these data may be used to develop guidelines for the reporting and management of ECFs.

The ACRIN 7151 study is retrospectively reviewing cases from 520 of the 2,531 ACRIN 6664 study participants assigned to one of three groups: Group E3/E4 excluding pulmonary nodules (n = 141), Group E3/E4 with reporting pulmonary nodules (n = 19), and Group E1 (the control group) having a normal exam (n = 260). The costs of follow-up diagnostic imaging, hospitalization, and interventional procedures associated with ECFs will be estimated for the entire cohort using Medicare reimbursement rates and then divided by the total number of participants to yield the average additional cost of evaluating ECFs per CTC exam.

1.Johnson CD, Chen M, Toledano AY, et al. “Accuracy of CT Colonography for Detection of Large Adenomas and Cancers.” N Engl J Med 2008;359(12):1207–12.
2. Ristvedt SL, McFarland EG, Weinstock LB, et al. “Patient Preferences for CT Colonography, Conventional Colonoscopy, and Bowel Preparation.” Am J Gastroenterol 2003;98(3):578–85.
3.Pickhardt PJ, Hassan C, Laghi A, et al. “Cost-Effectiveness of Colorectal Cancer Screening with Computed Tomography Colonography: The Impact of Not Reporting Diminutive Lesions.” Cancer 2007;109(11):2213–21.
4.Hassan C, Pickhardt P, Laghi A, et al. “Computed Tomographic Colonography to Screen for Colorectal Cancer, Extracolonic Cancer, and Aortic Aneurysm: Model Simulation with Cost-Effectiveness Analysis.” Arch Intern Med 2008;168(7):696–705.

By Nancy Fredericks, MBA, and Julie Catagnus, MPH, ELS
Nancy Fredericks, MBA (This email address is being protected from spambots. You need JavaScript enabled to view it.), is communications director, ACR Clinical Research Center. Julie Catagnus, MPH, ELS, is a freelance writer.

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