Cancer Screening Guidelines Don’t Indicate Benefits, Harms

March 9, 2016

When considering cancer screening, patients and physicians need better descriptions of both benefits and harms.

Most cancer prevention and screening recommendation statements do not quantify benefits and harms, or they are presented in an asymmetric manner, according to a study published in the Journal of the National Cancer Institute.

Researchers from the Veterans Affairs Medical Center in Ann Arbor, MI, examined U.S. guidelines for cancer prevention and screening, to determine how they presented benefits and harms.

The researchers searched for cancer screening and prevention recommendations between November 20, 2013, and January 1, 2014, and updates were reviewed through July 1, 2015. The 55 recommendations from 32 guidelines were from the United States Preventive Services Task Force, American Cancer Society, American College of Physicians, National Comprehensive Cancer Network, and other U.S. guidelines within the National Guidelines Clearinghouse.

The study’s primary outcome was to identify the benefit-harm “comparability” rating for each recommendation, based on how benefits and harms were presented. If the recommendations presented absolute effects for both benefits and harms, they received a “comparable” rating. Other recommendations received an incomplete rating or an asymmetric rating based on prespecified criteria.

The results showed that only 17 recommendations (39.7%) received a comparable rating. Eight (14.5%) received an incomplete rating, and 30 (54.5%) received an asymmetric rating.

"Almost all medical interventions have tradeoffs between different types of benefits and harms," coauthor Tanner J. Caverly, MD, clinical lecturer of internal medicine, University of Michigan Medical School, and research investigator, VA Ann Arbor Healthcare System Center for Clinical Management Research, said in a release.[[{"type":"media","view_mode":"media_crop","fid":"46595","attributes":{"alt":"benefits, harms cancer screening","class":"media-image media-image-right","id":"media_crop_8087048242186","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"5420","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 190px; width: 190px; border-width: 0px; border-style: solid; margin: 1px; float: right;","title":"©howcolour/Shutterstock.com","typeof":"foaf:Image"}}]]

"Patients rely on doctors to base screening recommendations on sound judgment as to whether, in their individual context, the benefits outweigh the harms. For this judgment, doctors need a clear understanding, in quantitative and comparable terms, about the degree of potential benefit and the degree of potential harm."

Senior Author Angela Fagerlin, PhD, professor and chair at the University of Utah’s Department of Population Health Sciences and research scientist at the Salt Lake City VA, added, "By unevenly presenting the statistics, guidelines can unintentionally give a false picture of the benefits and harms. The relative risk of ’twice as likely’ sounds significant, but in terms of absolute risk it might represent a very small difference."

The researchers concluded that improved presentation of both benefit and harm in screening recommended guidelines would help both patients and clinicians have sufficient information in order to make informed decisions.