Background parenchymal enhancement (BPE) on MRI after resection of primary breast cancer is associated with an increased risk of second breast cancer, according to a study published in Radiology.

BPE is known to be associated with the development of primary breast cancer, but its association with second breast cancer has been unclear.

With this in mind, researchers evaluated data from 2668 patients who had resection of primary breast cancer and underwent MRI surveillance between 2008 and 2017. 

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The patients had a mean age of 49 years at the baseline surveillance MRI, and they had a total of 6055 MRI examinations.

Over a median follow-up of 5.8 years, 109 patients (4%) developed a second breast cancer. To be considered a second breast cancer, a tumor had to occur at least 1 year after each MRI and could be present in the ipsilateral or contralateral breast.

Most second breast cancers (71%) were invasive, but 29% were ductal carcinomas in situ. Patients had contralateral tumors (53%), ipsilateral tumors (45%), or both ipsilateral and contralateral tumors (2%). 

In a multivariable analysis, BPE on surveillance MRI was associated with an increased risk of second breast cancer (hazard ratio [HR], 2.1; 95% CI, 1.4-3.1; P <.001).

Other factors independently associated with an increased risk of second breast cancer included the presence of a BRCA1/2 mutation (HR, 6.5; 95% CI, 3.5-12.0; P <.001), age younger than 45 years at initial breast cancer diagnosis (HR, 3.4; 95% CI, 1.7-6.4; P <.001), and having hormone receptor-negative primary breast cancer (HR, 1.6; 95% CI, 1.1-2.6; P =.02).

The researchers noted that, although BPE at surveillance MRI was an independent predictor of second breast cancer, additional studies are needed to validate these results. 

This study was limited by the fact that it included only patients referred for breast MRI surveillance and did not include varying breast densities. In addition, the researchers did not evaluate whether breast MRI was performed before breast cancer diagnosis in the same patients. 

“Assessing whether and how changes in BPE before and after breast cancer treatment affect the second breast cancer risk was beyond the scope of our study,” the researchers noted.


Lee SH, Jang M-j, Yoen H, et al. Background parenchymal enhancement at postoperative surveillance breast MRI: Association with future second breast cancer risk. Radiology. Published online August 30, 2022. doi:10.1148/radiol.220440