Breast Cancer Screening Programs With Largest Volumes Get Best Results

Accurate diagnoses are directly related to the number of mammograms interpreted by a physician, according to a UCSF study published in the March issue of the Journal of the National Cancer Institute. The study was done to understand factors that affect quality in mammography. The participants were each given a set of 60 mammograms to interpret. From the United States, 60 radiologists were divided into three groups: low-, medium- and high-volume radiologists who read 100, up to 300, or greater than 300 mammograms per month. Included in the study were 194 radiologists from the United Kingdom, all rated as high volume. Sensitivity, or the ability to detect cancer, was higher among the high-volume readers. UK readers were as accurate as the US readers.

The conditions under which physicians provide mammography vary widely. In the US, mammography is provided in a variety of settings, and the minimum reader volume is 480. Most US radiologists therefore do not read a high volume of mammograms, whereas in the UK readings are provided in centralized centers where the minimum annual reading volume is 5000 mammograms per year. The article concludes that there may be an opportunity to improve quality and efficiency by re-engineering the organization of US mammography screening programs.

The difference between the studied nations in how mammography results are handled is also significant. In the US, physicians are much more likely than physicians in the UK to recommend a mammogram be followed by a biopsy. Non-surgical biopsy (stereotactic or fine needle aspiration) in the UK reveals a cancer 30-60% of the time. This rate is similar to some of the most experienced breast cancer screening programs in the US which report finding cancer in 37-40% of non-surgical biopsies. Some studies report rates as low as 11%, meaning that most were performed in response to mammograms interpreted falsely as positive. The intent to maximize sensitivity (identify all potential cancers) is one of the reasons cited for the acceptance in the US of false positives. This study maintains that minimizing flase positives has not been shown to be associated with a lack of thoroughness in detecting cancer. The bias for more biopsies in the US may actually reflect a cultural bias rather than a quality advantage. Many women undergo biopsies for benign findings, which causes great emotional distress…and more than $1 billion annually.