The presence of "dense" breast is a double-edged sword when you need to be screened for breast cancer: dense breast tissue can increase the risk of cancer, as well as complicate the detection of tumors during mammography.
Given that in the US the recommendations have not yet registered an additional screening, doctors can decide whether to carry out an MRI is necessary after the negative results of mammography in women with dense breasts.
A new randomized controlled trial introduced the first high-quality evidence that the use of MRI in addition to mammography can improve the early diagnosis of breast cancer in women with very dense breast tissue.
The results of the work of scientists was published in «New England Journal of Medicine.».
"The additional screening with MRI in women with dense breast tissue led to the diagnosis of a much smaller number of interval cancers than when only mammography" - the scientists said.
The study showed that MRI was able to reduce the number of interval tumors twice.
Interval tumors detected between screening tests - mammary tumors are detected within two slots after sriningovoy mammography negative and before the next scheduled mammography. Reducing cancer interval may indicate that these tumors were discovered before they could become symptomatic.
The study also showed that using MRI diagnosed more slow-growing and less aggressive cancers. However, not all tumors detected at an early stage, in fact, cause symptoms or death. Thus, the question remains whether the early detection of breast cancer leads to MRI to improve survival in women with dense breasts.
"It is unclear how many of malignant tumors found in our study were life-threatening, and what proportion of them were found as a result of over-diagnosis" - the researchers said.
Furthermore, additional MRI had a false positive rate of 8%. And almost 74% of women who underwent an MRI and a biopsy of the breast, in fact, did not have breast cancer.
The study was conducted within the framework of population screening programs in eight hospitals and four regional screening centers in the Netherlands in the period from December 2011 to November 2015. It was attended by 40 373 women aged 50 to 75 years who have had an extremely dense breast tissue and normal results of screening mammography. Of these, 8061 the woman was randomly selected for additional MRI. Data on cancer diagnosis came from the Netherlands Cancer Registry.
Fifty-nine per cent of women who were offered an additional MRI, have accepted the offer.
Participants in MRI group had lower overall incidence of cancer (2.5 per 1,000 examinations) as compared to the group treated only mammography (5.0 per 1,000 examinations) for a statistically significant difference in terms of 2.5 per 1,000 examinations (95% confidence interval, from 1,0 to 3,7; P <0,001).
Among the participants, who underwent an MRI, from 454 (6.5%) had abnormal results skanirovniya, and they were subjected to additional testing. In total, 300 of them (6.3%) underwent a biopsy of the breast. Of these, 79 had cancer really: 64 (81%) of them were invasive tumors, while 15 (19%) - ductal carcinoma in situ (early form of cancer with a low risk of invasiveness). Most of these diseases are at an early stage of 0 or 1.
MRI sensitivity was 95.2%, and specificity - 92%. Among women who underwent MRI and were recalled for additional testing, 17.4% were diagnosed with breast cancer. Among women who have had MRI and breast biopsy, 26.3% were diagnosed with breast cancer.
Among women undergoing MRI, 0.1% had adverse effects such as vasovagal reaction contrasting reaction or infiltration intravenous line.