Digital breast tomosynthesis identifies more breast cancers than conventional digital mammography, according to two studies presented at the last European Congress of Radiology (ECR 2017). Furthermore, the rates of recall between the two modalities are comparable, according to the researchers.
Both studies examined the use of digital tomosynthesis in a screening setting. In one, researchers found digital tomosynthesis identifying 80% more cancers than digital mammography. In the other, researchers found that the breast cancer detection rate was about 50% higher for women screened with digital tomosynthesis compared with women screened with digital mammography.
In an era where the question remains whether digital tomosynthesis is ready to replace digital mammography for breast cancer screening, the evidence continues to grow in favor of the former.
study italian
In the first study, researchers from the city of Reggio Emilia, in northern Italy, analyzed data from more than 19,000 women who were randomized to receive digital mammography or digital mammography plus digital tomosynthesis, from March 2014 to March 2016. a double screening exam only once, according to researcher Dr. Valentina Lotti, da Archpedale Santa Maria Nuova, in Reggio Emilia.
Women aged between 45 and 70 years were randomized into random groups. The digital mammography group included 9782 women, while the digital tomosynthesis plus digital mammography group included 9623 women.
Digital mammography detected 45 cancers (six in situ) and digital mammography plus digital tomosynthesis detected 79 cancers (14 in situ).
The overall relative detection rate was 1.8, while the relative detection rate for cancer in situ was 2.4. The researchers found no difference by breast density. However, digital tomosynthesis showed great improvement for smaller tumors (10 mm to 20 mm), with a relative detection rate of 2.6.
“In our randomized study, 80% more cancers were identified in the study group compared to the control group. This detection is similar to in situ, invasive, pT1 [small] cancers, and dense, fat breasts,” said Lotti.
Norwegian study
In the next study, Dr. Tone Hovda and colleagues at Drammen Hospital in Drammen, Norway, compared the rate of recall and the breast cancer detection rate after one year of screening with synthetic imaging and digital tomosynthesis versus digital mammography in the Norwegian breast cancer screening program. They found that the rate of screen-detected cancer increased by 50% in the digital tomosynthesis group.
A total of 18,172 women aged between 50 and 69 living in the city of Oslo were screened with digital tomosynthesis in 2014, while a control group of 30,883 women were screened with digital mammography.
The findings indicate that the rate of recall did not differ in the comparison between digital tomosynthesis and digital mammography, most likely due to a rate of recall already downloaded in Norway.
However, the positive predictive value (PPV) of withdrawals and biopsy was higher for the experimental group than for the control group.
“This implies that the number of false positives in recalls is reduced for the tomosynthesis group, and this is an important benefit for both women and society, as it reduces the burden of recalls unnecessary," said Dr. Hovda.
“Due to the increased rate of breast cancer detected by nearly 50% screening for those screened with synthetic 2D and digital tomosynthesis compared to those screened with regular 2D digital mammography and reduced false positives, digital tomosynthesis is the superior modality” , noted.
Concerns about the added radiation dose of digital tomosynthesis due to the need for a 2D acquisition have been addressed by the use of synthesized 2D mammography, in which the 2D image is derived from digital tomosynthesis data.
Other objections to digital tomosynthesis as a screening tool include increased reading time, increased data loading, overdiagnosis issues and what kind of extra cancers will be diagnosed. "All these questions need further investigation," concluded Dr. Hovda.
Source: AuntMinnie.com