#VisualAbstract: Preoperative breast MRI may reduce need for adjuvant radiotherapy for women with unifocal breast cancer

1. There were similar rates of ipsilateral invasive recurrence among the postoperative adjuvant radiotherapy group (group 1) and non-radiotherapy group (group 2).

2. 2% of patients in the total cohort underwent mastectomy and all of them were in the non-radiotherapy group.

Evidence Rating Level: 1 (Excellent)

Study Rundown: Adjuvant breast radiotherapy is a common practice in early breast cancer treatment, although some suggests it may be overtreatment. This randomized controlled trial aimed to explore whether the use of preoperative MRI can identify women with localized unifocal breast cancer who can safely avoid radiotherapy. The primary outcome was ipsilateral invasive recurrence rate (IIRR) at 5 years, while key secondary outcome was IIRR at 10 years, and regional and distant recurrence. Study results showed that patients with unifocal malignancy on breast MRI who were eligible to omit radiotherapy had similar rates of ipsilateral recurrence compared to those who underwent radiotherapy. According to study results, women with unifocal breast cancer on MRI and favorable pathology staging may be able to consider safely omit radiotherapy. Although well-done, this study was limited by its non-randomized design, affecting the validity of results.

Click to read the study in The Lancet

Relevant Reading: Breast-Conserving Surgery with or without Irradiation in Early Breast Cancer

In-depth [randomized-controlled trial]: Between May 17, 2011, and May 6, 2019, 443 patients were screened for eligibility across 4 academic hospitals in Australia. Included were women ≥ 50 years old with cT1N0 non-triple-negative breast cancer eligible for breast-conserving surgery (BCS). Altogether, 443 patients (201 in systemic therapy alone [group 1] and 242 in radiotherapy plus systemic therapy [group 2]) were included in the final analysis. Patients in group 1 had a lower IRRR at 5 years than those in group 2 (1.0% vs. 1.7%). In group 1, one local recurrence occurred at 4.5 years and a second at 7.5 years. In group 2, 9 patients underwent mastectomy (2% of total cohort). This trial showed the effect of combining MRI and pathology findings on quality-adjusted life-years. Findings from this study suggest that women with unifocal breast cancer on MRI and favorable pathology can safely omit radiotherapy.

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