Postoperative surveillance MRI may reveal risk for second breast cancer
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Background parenchymal enhancement at surveillance breast MRI appeared independently associated with future second breast cancer risk among women with a personal history of breast cancer, according to study results published in Radiology.
Methods
Although background parenchymal enhancement (BPE) is a risk factor for breast cancer, studies have not explored the association between BPE and second breast cancer risk, according to researchers.
“Postoperative surveillance breast MRI is increasingly being performed because of its higher cancer detection rate than mammography,” Su Hyun Lee, MD, PhD, radiologist in the department of radiology at Seoul National University Hospital in Seoul, Republic of Korea, told Healio. “BPE on postoperative surveillance breast MRI is usually minimal after adjuvant treatment including radiation therapy, chemotherapy or endocrine therapy. However, in some women, BPE at postoperative surveillance breast MRI is increased and BPE on screening breast MRI is a known risk factor for breast cancer development.”
Lee and colleagues sought to assess whether BPE at surveillance breast MRI is associated with risk for second breast cancer — defined as ipsilateral breast tumor recurrence or contralateral breast cancer diagnosed at least 1 year after each surveillance breast MRI examination. Their retrospective study included 2,688 women (mean age at baseline surveillance breast MRI, 49 years) who underwent surgery for primary breast cancer between 2008 and 2017 and had no prior diagnosis of second breast cancer.
Researchers used a four-category classification of minimal, mild, moderate or marked to qualitatively assess BPE at surveillance breast MRI. They additionally evaluated factors associated with future second breast cancer risk using the multivariable Fine-Gray subdistribution hazard model.
Median follow-up was 5.8 years.
Findings
Researchers identified 109 second breast cancer cases, including 49 ipsilateral, 58 contralateral and two ipsilateral and contralateral breast cancers. Moreover, 32 (29%) were ductal carcinoma in situ and 79 (71%) were invasive breast cancers.
Factors independently associated with increased risk for future second breast cancer included mild, moderate or marked BPE at 1 year after breast MRI surveillance (HR = 2.1; 95% CI, 1.4-3.1), age younger than 45 years at initial breast cancer diagnosis (HR = 3.4; 95% CI, 1.7-6.4), a positive BRCA1 or BRCA2 genetic test result (HR = 6.5; 95% CI, 3.5-12) and a negative hormone receptor status in the initial breast cancer (HR = 1.6; 95% CI, 1.1-2.6).
Implications
The findings may help stratify the risk for second breast cancer in women with a personal history of breast cancer and to establish personalized imaging surveillance strategies in terms of imaging modality and monitoring interval selection, Lee said.
“For example, women with minimal BPE at surveillance breast MRI may no longer need to undergo contrast-enhanced breast MRI every year if other risk factors are absent,” she continued. “The association between changes in BPE between screening or preoperative breast MRI and postoperative surveillance breast MRI and the development of second breast cancer was not addressed in our study and, therefore, requires further study. In addition, research on the multimodality risk assessment combining mammography, ultrasound, and MRI to create models for the risk of second breast cancer and interval cancer are needed to establish tailored surveillance strategies.”
The study by Lee and colleagues contributes to the growing body of literature demonstrating that BPE is a modifiable breast cancer risk factor, according to an accompanying editorial by Bethany Niell, MD, PhD, section chief of breast imaging at H. Lee Moffitt Cancer Center and professor in the department of oncologic sciences at University of South Florida.
“We know that numerous factors influence patients’ BPE during their lifetimes. However, it is not yet known whether an optimal strategy exists for characterizing the risk [for] breast cancer based on a BPE measure at any single time point,” Niell wrote.
She said many questions remain about whether and how to best incorporate BPE to better predict first and subsequent breast cancer diagnoses.
“Do patients with higher BPE at screening breast MRI before a breast cancer diagnosis warrant more aggressive primary chemoprevention regimens?” Niell wrote. “The results from the study by Lee and colleagues provide additional impetus for future avenues of research into the clinical and biologic implications of BPE at breast MRI.”
References :
- Breast MRI illuminates risk of second breast cancer (press release). Available at: press.rsna.org/timssnet/media/pressreleases/14_pr_target.cfm?ID=2366. Published Aug. 30, 2022. Accessed Aug. 31, 2022.
- Lee SH, et al. Radiology. 2022;doi:10.1148/radiol.220440.
- Niell BL. Radiology. 2022;doi:10.1148/radiol.221901.
Perspective
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Laura Dean, MD
Without question, we have increasing evidence that background parenchymal enhancement (BPE) is a risk factor for breast cancer development. This seems to align with intuition, in that patients with the more active breast tissue on MRI (ie, greater level of BPE) should be the ones with increased risk for developing malignancy in the breast. However, the degree to which BPE is an independent predictor of risk is multifactorial, and additional investigation is needed to further highlight this risk as it applies to development of an additional breast malignancy among people with cancer.
In a similar fashion, it is now accepted that increased breast density on mammography also is an independent risk factor for breast cancer. It is interesting, though, that mammographic breast density is not necessarily predictive of a patient’s BPE on MRI. In other words, a person with breast cancer with extremely dense tissue on mammography may demonstrate minimal BPE on MRI. Which implies a greater risk? Breast density? BPE? The challenge becomes teasing out the true risk in a case such as this, where both breast density and BPE have important implications for developing an additional breast cancer.
MRI is a respected supplemental tool for screening among high-risk patients, and it provides valuable information regarding disease extent and treatment response among patients diagnosed with a breast malignancy. The use of subsequent screening breast MRI for patients who have had breast cancer is not automatic. Existing guidelines state which patients may benefit from supplemental screening MRI, including those with dense tissue, those aged younger than 50 years at diagnosis, and those with specific subtypes of breast cancer.
Discussions around enhanced screening protocols should continue to emphasize the importance of screening mammography, which remains the mainstay of breast cancer screening. Risk stratification is important in order to identify which patients may benefit from enhanced screening, where indicated. The degree to which BPE is an independent risk factor for breast cancer development, and the implications on surveillance for patients with prior cancer, requires further investigation in future trials.
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