Magnetic resonance imaging identifies multifocal and multicentric disease in breast cancer patients who are eligible for partial breast irradiation

Abstract

BACKGROUND. In this retrospective study, the authors hypothesized that magnetic resonance imaging (MRI) would alter partial breast irradiation (PBI) eligibility by identifying cancers outside the PBI volume compared with mammography alone. METHODS. Since 2002, MRI was used nonselectively at the authors' institution for the staging of patients with nonmetastatic breast cancer. Of 450 consecutive patients with invasive breast cancer, 110 patients who were eligible for PBI were identified by using criteria outlined by National Surgical Adjuvant Breast and Bowel Project B‐39/Radiation Oncology Group trial 0413 based on mammography, ultrasonography, and initial pathology. In that trial, patients were randomized (stage I/II invasive cancers that measured ≤3 cm and ≤3 positive lymph nodes) to receive either whole‐breast radiotherapy or PBI. MRI reports were reviewed to determine whether MRI identified secondary lesions 1) within the same quadrant (multifocal), 2) in a different quadrant (multicentric), or 3) in the contralateral breast. These lesions were pathologically proven carcinoma and would have rendered the patient ineligible for PBI. RESULTS. MRI identified secondary lesions in 10% of patients (95% confidence interval [CI], 4.4%‐15.6%). Multifocal disease was identified in 3.6% (95% CI, 1.4%‐9%), multicentric disease was identified in 4.5% (95% CI, 2%‐10.2%), and contralateral disease was identified in 1.8% (95% CI, 0.5%‐6.4%). The proportion of patients with false‐positive MRI findings was 4.5% (95% CI, 2%‐10.2%). The positive predictive value of MRI was 72.2% (95% CI, 46.4%‐89.3%). CONCLUSIONS. MRI identified frequent secondary cancers that would not be removed routinely by surgery or targeted in the radiation field if treated with PBI. The current data suggest that MRI should be considered to assess PBI eligibility to minimize potential local failures. Cancer 2008. © 2008 American Cancer Society.

Extra-mammary findings in breast MRI

“…MRI is an established tool for breast cancer diagnosis and staging [12][13][14][15][16][17]. As the clinical application of breast MRI becomes more widespread, a parallel increase in the number of incidental extramammary findings is reasonably expected.…”

Classification System for Identifying Women at Risk for Altered Partial Breast Irradiation Recommendations After Breast Magnetic Resonance Imaging

“…Multifocality has also been evaluated, with a finding of a 4% to 9% change in PBI recommendations (13)(14)(15)(16)(17)(18). Contralateral breast cancer diagnoses after MRI have produced a 2% to 4% change in PBI recommendations (13)(14)(15)(16)(17)(18).…”

“…Previous publications have evaluated alterations in PBI recommendations after MRI (13)(14)(15)(16)(17)(18). These studies have examined tumor characteristics including multicentric, multifocal, and contralateral disease.…”

The role of magnetic resonance imaging in early breast cancer

“…[46][47][48][49] The prospect of using MRI to tailor the approach to breast radiotherapy has been evaluated in the setting of partial breast irradiation. [53][54][55] These studies have been retrospective with various entry 54 performed a retrospective analysis of 450 patients, of whom 110 were eligible for partial irradiation. Additional disease (multifocal or multicentric) was found in 10%, with a false positive rate of 4.5%.…”