3D mammography more effective for breast cancer screening

The research team screened 15,000 women over a period of five years. Participants underwent screening with two-view digital mammography followed by one-view digital breast tomosynthesis with reduced compression in the mediolateral oblique view at one screening visit. Images were read with masked double reading and scoring by two separate reading groups, one for each method, made up of seven radiologists.

The primary outcome measures were sensitivity and specificity of breast cancer detection. Secondary outcome measures were screening performance measures of cancer detection, recall, and interval cancers (cancers clinically detected between screenings), and positive predictive value for screen recalls and negative predictive value of each method.

"With breast tomosynthesis, 34 percent more cancer tumors were detected compared to the current standard mammography screening. At the same time, we were able to reduce the compression of the breast during the examination, something that may encourage more women to participate in screening," explains Zackrisson.

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"We did, however, need to call back a few more women for additional examinations compared to traditional mammography. We needed to confirm that these women did not have cancer, as this method finds more structures in the breast in general. So, there was an increased call-back rate." Zackrisson continues.

In traditional mammography screening, all breast tissue is captured in a single image. Breast tomosynthesis, on the other hand, is three-dimensional and works according to the same principle as what is known as tomography. This means that several low-dose x-ray images are taken of the breast from different angles, which are reconstructed by a computer to show thin layers of the breast. With more and improved image information and less overlapping tissue structures, the chance of detecting tumors increases. Further, the radiation dose may be lowered in certain circumstances.

"There is a need to improve screening for many women, and breast tomosynthesis is clearly the most appropriate method to transition to in breast cancer screening. Breast tomosynthesis will be introduced, it's just a question of when and to what extent," says Sophia Zackrisson.

Breast tomosynthesis is already used at Skåne University Hospital, among other places, to investigate suspected breast cancer. Prior to a possible large-scale introduction in the general breast cancer screening programme, the research team is now conducting a cost-benefit study.

The lack of radiologists who can review the increased image material generated by 3D methods presents a further challenge before large-scale introduction. However, the method used at Skåne University Hospital may be more efficient than those previously examined in international studies. In Skåne, only the 3D method has been used whereas other studies have combined 3D with traditional mammography screening. This leads to more image material and a higher radiation dose.

"We have shown that we can achieve the same result with a simpler and perhaps even better method," says Sophia Zackrisson.

In the future, parts of the image review in connection with breast tomosynthesis may be automated with the help of computers, but it will take time. There is currently a lack of appropriate ready-to-use and tested software. Studies are underway, including in Sophia Zackrisson's research team.

"Breast cancer screening by use of one-view digital breast tomosynthesis with a reduced compression force has higher sensitivity at a slightly lower specificity for breast cancer detection compared with two-view digital mammography and has the potential to reduce the radiation dose and screen-reading burden required by two-view digital breast tomosynthesis with two-view digital mammography," write the authors.

For further reference follow the link: https://doi.org/10.1016/S1470-2045(18)30521-7