Ya-Chen Tina Shih and Tina Yen on Trends in Preoperative Breast MRI

Compared with mammography or ultrasound, the clinical benefit of preoperative breast magnetic resonance imaging (MRI) for early-stage cancer is controversial, but its use has been steadily increasing, said authors of a study in JCO Oncology Practice.

Ya-Chen Tina Shih, PhD, of the University of Texas MD Anderson Cancer Center in Houston, and colleagues analyzed claims data of approximately 92,000 women with early-stage breast cancer who underwent surgery from 2008 through 2020.

For patients younger than 65, the rate of preoperative MRI increased by 25% — from 48% in 2008 to 60% in 2020. The increase was similar (26%) for patients 65 and older during that time: from 27% to 34%, the study found. Non-Hispanic Black women younger than 65 were 25% less likely to undergo preoperative MRI compared with non-Hispanic white women (OR 0.75, 95% CI 0.70-0.81), and the results were similar for black women age 65 and older.

“Growing use of preoperative breast MRI will increase costs of breast cancer care for patients and the health care system, calling for more research to identify patients who will truly benefit from this practice to guide interventions that promote appropriate use and dis-incentivize inappropriate use of this expensive technology,” the researchers concluded.

In the following interview, Shih and co-author Tina W.F. Yen, MD, of Medical College of Wisconsin in Milwaukee, discussed additional details of the study and its implications.

Why do you think use of preoperative MRI has been increasing despite the lack of clear evidence for its benefit?

Despite studies published to date demonstrating no effect of preoperative breast MRI on the rate of re-excision after breast-conserving surgery, locoregional recurrence, or survival, the rates of preoperative breast MRI continue to increase.

This increase may be attributed to provider and patient preferences, as well as an increase in the proportion of younger women and Asian women (both are more likely to have denser breasts) being diagnosed with breast cancer. Breast MRI, with its higher sensitivity in dense breasts, could potentially better delineate extent of disease and better identify additional sites of cancer in either breast.

In addition, with increasing rates of genetic testing, an increase in the proportion of women with a genetic predisposition for breast cancer or family history of breast cancer may account for the increasing use of preoperative breast MRI to evaluate for additional sites of cancer in either breast.

Finally, as the use of neoadjuvant systemic therapy increases, breast MRI performed pre-treatment to determine eligibility and post-treatment to assess response may also account for increasing use of preoperative breast MRI.

What are possible reasons for the lower use of preoperative MRI among black patients?

The reasons Black women have a lower rate of preoperative breast MRI use is unclear and likely multifactorial. One possible explanation is that a lower proportion of Black women have dense breasts, compared to white women, and therefore potential benefits of MRI (e.g., extent of disease, contralateral breast assessment) may be less.

In addition, there may be differences in provider recommendations for MRI, patient preferences regarding undergoing MRI, access to breast MRI, and other effects of systemic racism that could impact use of MRI.

What did your study find about geographical differences in preoperative MRI use, and are there any possible explanations for this?

We found significant variation in preoperative breast MRI use by geographical location. Regardless of age group, women were more likely to undergo preoperative breast MRI if they lived in the Mountain, Mid-Atlantic, and South Atlantic [Census] regions. Women were less likely to undergo MRI if they lived in New England, the East North Central, and the West South Central regions. Women younger than 65 in the East South Central region and 65 and older in the West North Central region were also less likely.

Many reasons can contribute to such geographical differences. For example, the availability of breast MRI machines is lowest in the East South Central and West South Central regions. Other likely contributing factors are provider preference, patient preference for breast MRI, type of surgery (lumpectomy or mastectomy), and other unmeasured factors.

Future research using a mixed-methods approach is needed to better understand these geographical differences.

What clinical factors were positively associated with preoperative MRI, and how do your findings on this compare with other studies?

Our study found that women who were younger, healthier, had a family history of breast cancer, had axillary nodal disease, and who underwent neoadjuvant chemotherapy and/or mastectomy were more likely to undergo preoperative breast MRI. These factors are known to be associated with preoperative breast MRI use; our findings confirm those of many prior studies. However, prior studies largely focused on elderly women with breast cancer. Our analysis adds to the literature by providing information to better understand preoperative MRI use in younger women.

Read the study here.