Patients with early-stage, hormone receptor-negative breast cancer do not experience improved survival or reduced recurrence rates from preoperative breast MRI compared to standard diagnostic mammography, according to findings presented at the San Antonio Breast Cancer Symposium. The phase III Alliance A011104/ACRIN 6694 clinical trial involved 319 patients with stage 1 or 2 HR-negative breast cancer who were eligible for lumpectomy and did not have BRCA1/2 mutations, bilateral disease, or a history of prior breast cancer.
All participants underwent diagnostic mammography before being randomly assigned either to receive additional imaging by breast MRI or no further imaging. After a median follow-up of just over five years, the rates of remaining free from locoregional recurrence were similar: 93.2% in the MRI group and 95.7% in the non-MRI group, a difference that was not statistically significant.
"The rate of locoregional recurrence was quite low in both arms of the trial, and the inclusion of MRI did not lower it any further," said Isabelle Bedrosian, MD, lead investigator and professor at The University of Texas MD Anderson Cancer Center.
Five-year distant recurrence-free survival and overall survival rates also showed no significant differences between groups. Among those who received neoadjuvant chemotherapy, pathologic complete response rates were numerically lower in the MRI arm (36%) than in the non-MRI arm (52%), but this difference was not statistically significant due to small sample size.
"Our trial results show that there is no improvement in the oncologic outcomes of patients who undergo preoperative breast MRI staging as compared with those who do not," Bedrosian stated. She referenced previous data from the COMICE clinical trial indicating that preoperative MRI does not reduce subsequent surgery rates.
"Our results further imply that there is no clinical utility to using preoperative MRI for the diagnostic workup of breast cancer patients to guide surgical treatment," Bedrosian said. "We conclude that the routine use of MRI in this context is not warranted."
Bedrosian suggested that preoperative MRI may offer little benefit because it rarely detects additional lesions beyond what mammography reveals or because finding and removing such lesions does not affect recurrence rates. Ongoing analyses are investigating how often additional lesions were identified by MRI during this study.
She noted limitations including a high proportion (93.4%) of clinically node-negative patients and an older average patient age (58.9 years), though subgroup analysis indicated women under age 50 also saw no added benefit from preoperative MRI.
The research was funded by the National Cancer Institute at the National Institutes of Health.
