Digital Breast Tomosynthesis

A new imaging technology is considered to be investigational before peer-reviewed studies have been published validating the clinical utility of the technology. Such studies already have been published for DBT. These are summarized and the supporting peer-reviewed articles are cited in the ACR letter to insurers.

As discussed in the ACR letter to insurers, several published and peer-reviewed articles on DBT are more than sufficient to justify its clinical utility. Indeed, there are more such articles already published on DBT, involving a much larger population of women, than had been published on FFDM when insurance coverage was provided for FFDM.

It is impractical to wait for evidence of additional mortality reduction attributable to the use DBT. That would require at least one randomized controlled trial, an extremely expensive and lengthy process that has not been used during the past decade for any breast imaging technology. Furthermore, the demonstration of technology-specific additional mortality reduction has not been required to justify insurance coverage for either FFDM or any other breast imaging technology.

There are several outcome metrics that have been validated as surrogate markers to predict mortality reduction by retrospective study of data from the randomized controlled trials involving film-screen mammography conducted several decades ago. These surrogate markers include tumor size, rate of node negativity, tumor stage, and rate of interval cancers. There already is ample evidence described in the ACR letter to insurers involving three of the four surrogate markers (all except for rate of interval cancers).

Since all of the surrogate markers are valid predictors of mortality reduction, it is not necessary to have evidence for the fourth marker when we already have sufficient evidence for three of the markers. Furthermore, the demonstration of technology-specific additional decrease in the rate of interval cancers has not been required to justify insurance coverage for either FFDM or any other breast imaging technology.

The total radiation dose of combined DBT and FFDM examination, although approximately twice that of FFDM examination alone, is well within the FDA-established range of acceptable dose for a mammography examination (approximately 2.5 cGy per view for combined DBT/FFDM, 3.0 cGy per view FDA ceiling). Furthermore, mammography patients who are concerned about the additional, albeit acceptable dose of combined DBT/FFDM have the option to decline the DBT component, so this should not be an issue for insurers.