Preoperative MRI does not reduce positive margins after breast-conserving surgery
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Key takeaways:
- MRI appeared more likely to be used for younger patients and those with smaller tumors.
- Patient age and tumor size appeared to be better predictors of margin status than use of preoperative MRI.
Preoperative MRI did not help reduce positive margin status among women who underwent breast-conserving surgery, according to data presented at American Society of Breast Surgeons Annual Meeting.
Instead, patient age and tumor size are important characteristics to help predict margin status, researchers concluded.
Background and methodology
Breast-conserving surgery has been “a mainstay of breast cancer management,” and this approach confers safe and reliable outcomes compared with mastectomy when tumor-free margins are attained, Marissa Howard-McNatt, MD, FACS, FSSO, professor of surgery and director at the breast cancer center at Wake Forest Baptist Health in Winston-Salem, North Carolina, said during a presentation.
“[However], breast-conserving surgery can be associated with a higher rate of positive margins, ranging up to 27% in the literature,” Howard-McNatt added. “Re-excision surgery can contribute to greater morbidity, patient anxiety, poor cosmetic outcome and health care system overload.”
Preoperative imaging has been considered a potential strategy to assess extent of disease in order to mitigate risk and reduce reoperation, Howard-McNatt said. MRI has been shown to detect additional disease; however, it is associated with a higher false-positive rate, ranging up to 12%, she added.
Howard-McNatt and colleagues sought to determine whether preoperative MRI appeared associated with reduced positive margin status among women undergoing breast-conserving surgery.
Researchers used data from two randomized controlled trials — SHAVE 1 and SHAVE 2 — conducted at 10 centers that evaluated tumor cavity-shaved margins.
The study included 631 patients (mean age, 64 years; mean tumor size, 1.3 cm) with stage 0 to stage III breast cancer.
Investigators randomly assigned women to preoperative MRI (n = 193) or no MRI (n = 420) at surgeon discretion.
Results
About one-quarter of patients (26.1%; n = 165) had palpable tumors.
Approximately 32.8% had an extensive intraductal component, 7% had invasive lobular histology and 6.5% had received neoadjuvant chemotherapy.
Nearly one-third (30.5%; n = 193) had undergone MRI.
Patients who underwent MRI appeared less likely to have a positive margin (31.1% vs. 38.8%) than those that did not.
Upon multivariable analysis controlled for patient age, race, neoadjuvant chemotherapy receipt, extensive intraductal component, histologic subtype and tumor size, MRI did not appear associated with a higher rate of negative margins.
Researchers identified patient age (P = 0.032) and tumor size (P = .04) to be predictors of margin status.
MRI had been utilized more commonly for younger patients (median age, 63 years vs. 66 years) and those with smaller tumors (median, 2 cm vs. 2.1 cm).
Next steps
Researchers determined that preoperative MRI does not affect margin status, but instead that other characteristics should be taken into account.
“We conclude that MRI was associated with younger patients and smaller tumors, which may explain the trend toward lower margin positive data seen by multivariable analysis in this group,” Howard-McNatt said.
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Cairns A, et al. Does preoperative MRI reduce positive margins after breast conserving surgery? Presented at: American Society of Breast Surgeons Annual Meeting; April 26-30, 2023; Boston.
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