Healthcare professionals or doctors wearing masks look at a woman's breast mammogram in a labShare on Pinterest
Medical professionals use a mammogram to examine a woman’s breast for breast cancer. Picture alliance/Getty Images
  • In a large study of more than one million women, researchers compared how well 2D and 3D mammograms detect breast cancer.
  • They found that 3D mammograms were significantly more effective than 2D mammograms.
  • The scans are currently undergoing clinical trials.

Breast cancer is the most common cancer among women in the United States, and the second leading cause of cancer death in women after lung cancer.

According to the American Cancer Society, classifications of breast cancer stages include:

  • Localized — cancer has not spread outside of the breast
  • Regional — cancer has spread outside the breast to nearby structures
  • Distant — cancer has spread to distant parts and other organs of the body

The 5-year survival rate for breast cancer when detected early in its localized stage is 99%. The figure drops to 86% when cancer reaches the regional stage, and 30% when in the distant stage. Regular screening for breast cancer can help individuals identify cancer when it is more treatable.

Currently, the standard of care for screening is a two-dimensional (2D) digital mammography. Studies show that mammography can detect around 87% of breast cancers. This means that around 1 in 8 cases may not be detected.

Digital breast tomosynthesis (DBT), also called a 3D mammogram, is a newer screening technology that captures x-ray images from multiple angles allowing radiologists to see 3D images of breast tissue, as opposed to the single image from a standard 2D mammogram.

Research shows that DBT is linked to a 21% increase in cancer detection compared to mammography. It is also shown to have particularly good results for younger women and those with dense breasts.

Further study of screening methods for breast cancer could increase breast cancer survival rates.

Recently, researchers analyzed healthcare data from the U.S. to determine whether DBT or mammography yielded higher cancer detection rates.

Dr. Debbie Bennett, Associate Professor of Radiology at Washington University’s Siteman Cancer Center, not involved in the study, told Medical News Today:

“This study analyzed screening mammograms, which are done in women without symptoms for early detection of breast cancer. The study found that mammograms with tomosynthesis (3D mammograms) were better than standard digital mammograms at finding breast cancer and avoiding false positives.”

The study was published in Radiology.

For the study, the researchers analyzed healthcare data from 1,100,447 women aged 40 to 79 years old from across the U.S. All women were screened with either DBT or mammography between 2014 and 2020.

In total, 9,714 cancers were detected: 3421 from mammography and 6293 from DBT.

Ultimately, the researchers found DBT had a cancer detection rate of 5.3 per 1000 examinations, whereas mammography had a cancer detection rate of 4.5 per 1000 examinations.

DBT also delivered lower false positive and false negative results than mammograms. These findings remained after adjusting for potential confounders.

Whereas more people underwent biopsy after DBT, around 30% of biopsies from both DBT and mammograms returned positive.

This study also found that DBT works similarly for women with dense and non-dense breasts.

Dense breasts occur when breasts have more glandular and fibrous tissue than fatty breast tissue. This can make mammograms harder to read and reduce their accuracy. For this reason, the FDA now requires mammogram reports to include breast density information.

To understand when mammography or DBT may be preferable, Dr. Jennifer Chen, lead breast imager at City of Hope Orange County Lennar Foundation Cancer Center in Irvine, California, not involved in the study, told MNT:

“DBT generates three-dimensional images of the breast, allowing physicians to see the breast from more angles and in greater detail. 3D imaging is especially recommended for women with dense breasts because traditional two-dimensional often cannot produce a clear image when high-density tissue is present.”

Dr. Bennett noted that while DBT is generally preferable to standard mammography, the reverse may be true in rare situations, such as when women are unable to hold still for DBT.

MNT also spoke with Dr. Liane Philpotts, FACR, professor of Radiology and Biomedical Imaging at Yale School of Medicine, Section Chief of the Breast Imaging Eastern Region at Smilow Cancer Hospital and co-author of Breast Tomosynthesis, not involved in the study.

Dr. Philpotts said:

“For patients with predominantly fatty breasts (density A), 2D mammography will usually suffice. As soon as there is some fibro glandular breast density, DBT ’sees’ through the tissue better, resulting in more cancers detected and fewer [incorrect results]. Also, for women with dense breasts, having supplemental screening- via ultrasound or MRI, for example- has been shown that the advantages of DBT may not be as great.”

When asked about the limitations of the findings, Dr. Chen told MNT:

“A limitation of the study is that it is retrospective and observational. The researchers used data from women screened with 2D during an earlier period and compared it to those screened with 3D more recently, which means there is not an absolute comparison of the same cohort.”

“Additionally, because the 2D data lacked important patient characteristics, including breast density, race, and screening intervals, the population study group was not randomized, and there may have been selection bias. Also, the characteristics of detected cancers were not evaluated, and long-term outcomes for the 3D patients were not studied. Further research on the long-term benefits of 3D is important.” she added.

Dr. Philpotts told MNT that while DBT is preferable for most women, those with non-dense breasts may be better served by 2D mammograms alone as these require slightly less radiation.

Dr. Bennett added: “Although tomosynthesis mammograms seem preferable to standard mammography for most women, it is too early to say whether standard of care for breast cancer detection should change. A large trial is underway which randomly assigns women to either type of mammogram screening. Results from that trial should address the limitations described above and provide important information on whether the standard of care for breast cancer screening should change.”

MNT also spoke with Dr. Paul Friedman, Section Chief of Breast Imaging, Attending Radiologist, and Medical Director of the Rippel Breast Center, who was not involved in the study. Dr. Friedman told MNT:

It’s important for patients to know their risk factors for breast cancer- especially family and genetic history. Many genetic cancers can present early and be aggressive. Patients should use calculation tools provided by breast centers or online to calculate their risks. However, they should also be aware that even if they don’t have elevated risk they are still at risk for breast cancer with the general population which is significant- 1 in 8 women.”

“I would also remind patients that breast cancer detection is becoming an individualized experience and each patient in conjunction with their personal physician and radiologist may benefit from adjunct screening tools- such as ultrasound screening and Breast MRI. Not every test is the best test for every patient and it’s important to have your care tailored to what works best for you and what helps the radiologist evaluate your breast tissue the best,” he concluded.