Utility of Breast Magnetic Resonance Imaging in Determining Candidacy for Partial Breast Irradiation

Abstract

Purpose/Objective(s)Magnetic resonance imaging (MRI) identifies both invasive carcinoma and ductal carcinoma in situ (DCIS) with high sensitivity. MRI often finds cancers that are not detected by clinical exam and mammogram. We investigated the role of MRI in determining eligibility for partial breast irradiation (PBI) when performed in addition to standard imaging techniques.Materials/MethodsSince 2002, MRI was used non-selectively for the staging of patients with invasive cancer and DCIS. Of 444 consecutive patients with invasive breast cancer diagnosed between January 2002 and March 2008, 170 (38%) were eligible for PBI according to the criteria outline by National Surgical Adjuvant Breast and Bowel Project B-39/Radiation Oncology Group trial 0413 based on mammography, ultrasonography, and initial pathology. Prior to 2006, patients with DCIS could not be retrospectively assessed due to non-uniform microscopic size reporting. Of 50 evaluable patients with DCIS, 14 (28%) were deemed eligible for PBI. MRI reports were reviewed to determine whether MRI changed eligibility status by identifying additional lesions 1) within the same quadrant (multifocal), 2) within a different quadrant (multicentric), or 3) in the contralateral breast. MRI-identified lesions were pathologically confirmed as carcinoma and therefore rendered the patient ineligible for PBI.ResultsMRI identified secondary lesions in 7.6% (Confidence Interval (C.I.) 3.8-11.4%) of patients. In patients with invasive breast cancer, MRI identified additional disease in 7.6% (C.I. 3.7-11.6%). In patients with DCIS, MRI identified additional disease in 7.1%. In total, multifocal disease was identified in 2.2% (C.I. 0.9-5.5%), multicentric disease was identified in 4.3% (C.I. 1.4-7.3%), and contralateral disease was identified in 1.1% (C.I. 0.3-3.9%). Pathologic examination of MRI-identified lesions revealed invasive ductal carcinoma (IDC) in 28.6%, DCIS in 28.6%, and both IDC and DCIS in 42.8%. The median age of patients with secondary lesions detected by MRI was 57 years (range 45-83 years). The proportion of patients with false-positive MRI findings was 8.2% (C.I. 4.1-12.4%), and the positive predictive value of MRI was 56.3% (C.I. 39.1-73.4%). MRI was the only modality to identify the primary tumor in 3.8% of patients.ConclusionsIn women who are considered candidates for PBI based on mammogram, ultrasound, and initial pathology, MRI identified additional disease in 7.6% of patients rendering them ineligible for PBI. MRI should be increasingly considered in the staging of potential PBI candidates. Prospective study is needed to further define the true utility of MRI in this setting. Purpose/Objective(s)Magnetic resonance imaging (MRI) identifies both invasive carcinoma and ductal carcinoma in situ (DCIS) with high sensitivity. MRI often finds cancers that are not detected by clinical exam and mammogram. We investigated the role of MRI in determining eligibility for partial breast irradiation (PBI) when performed in addition to standard imaging techniques. Magnetic resonance imaging (MRI) identifies both invasive carcinoma and ductal carcinoma in situ (DCIS) with high sensitivity. MRI often finds cancers that are not detected by clinical exam and mammogram. We investigated the role of MRI in determining eligibility for partial breast irradiation (PBI) when performed in addition to standard imaging techniques. Materials/MethodsSince 2002, MRI was used non-selectively for the staging of patients with invasive cancer and DCIS. Of 444 consecutive patients with invasive breast cancer diagnosed between January 2002 and March 2008, 170 (38%) were eligible for PBI according to the criteria outline by National Surgical Adjuvant Breast and Bowel Project B-39/Radiation Oncology Group trial 0413 based on mammography, ultrasonography, and initial pathology. Prior to 2006, patients with DCIS could not be retrospectively assessed due to non-uniform microscopic size reporting. Of 50 evaluable patients with DCIS, 14 (28%) were deemed eligible for PBI. MRI reports were reviewed to determine whether MRI changed eligibility status by identifying additional lesions 1) within the same quadrant (multifocal), 2) within a different quadrant (multicentric), or 3) in the contralateral breast. MRI-identified lesions were pathologically confirmed as carcinoma and therefore rendered the patient ineligible for PBI. Since 2002, MRI was used non-selectively for the staging of patients with invasive cancer and DCIS. Of 444 consecutive patients with invasive breast cancer diagnosed between January 2002 and March 2008, 170 (38%) were eligible for PBI according to the criteria outline by National Surgical Adjuvant Breast and Bowel Project B-39/Radiation Oncology Group trial 0413 based on mammography, ultrasonography, and initial pathology. Prior to 2006, patients with DCIS could not be retrospectively assessed due to non-uniform microscopic size reporting. Of 50 evaluable patients with DCIS, 14 (28%) were deemed eligible for PBI. MRI reports were reviewed to determine whether MRI changed eligibility status by identifying additional lesions 1) within the same quadrant (multifocal), 2) within a different quadrant (multicentric), or 3) in the contralateral breast. MRI-identified lesions were pathologically confirmed as carcinoma and therefore rendered the patient ineligible for PBI. ResultsMRI identified secondary lesions in 7.6% (Confidence Interval (C.I.) 3.8-11.4%) of patients. In patients with invasive breast cancer, MRI identified additional disease in 7.6% (C.I. 3.7-11.6%). In patients with DCIS, MRI identified additional disease in 7.1%. In total, multifocal disease was identified in 2.2% (C.I. 0.9-5.5%), multicentric disease was identified in 4.3% (C.I. 1.4-7.3%), and contralateral disease was identified in 1.1% (C.I. 0.3-3.9%). Pathologic examination of MRI-identified lesions revealed invasive ductal carcinoma (IDC) in 28.6%, DCIS in 28.6%, and both IDC and DCIS in 42.8%. The median age of patients with secondary lesions detected by MRI was 57 years (range 45-83 years). The proportion of patients with false-positive MRI findings was 8.2% (C.I. 4.1-12.4%), and the positive predictive value of MRI was 56.3% (C.I. 39.1-73.4%). MRI was the only modality to identify the primary tumor in 3.8% of patients. MRI identified secondary lesions in 7.6% (Confidence Interval (C.I.) 3.8-11.4%) of patients. In patients with invasive breast cancer, MRI identified additional disease in 7.6% (C.I. 3.7-11.6%). In patients with DCIS, MRI identified additional disease in 7.1%. In total, multifocal disease was identified in 2.2% (C.I. 0.9-5.5%), multicentric disease was identified in 4.3% (C.I. 1.4-7.3%), and contralateral disease was identified in 1.1% (C.I. 0.3-3.9%). Pathologic examination of MRI-identified lesions revealed invasive ductal carcinoma (IDC) in 28.6%, DCIS in 28.6%, and both IDC and DCIS in 42.8%. The median age of patients with secondary lesions detected by MRI was 57 years (range 45-83 years). The proportion of patients with false-positive MRI findings was 8.2% (C.I. 4.1-12.4%), and the positive predictive value of MRI was 56.3% (C.I. 39.1-73.4%). MRI was the only modality to identify the primary tumor in 3.8% of patients. ConclusionsIn women who are considered candidates for PBI based on mammogram, ultrasound, and initial pathology, MRI identified additional disease in 7.6% of patients rendering them ineligible for PBI. MRI should be increasingly considered in the staging of potential PBI candidates. Prospective study is needed to further define the true utility of MRI in this setting. In women who are considered candidates for PBI based on mammogram, ultrasound, and initial pathology, MRI identified additional disease in 7.6% of patients rendering them ineligible for PBI. MRI should be increasingly considered in the staging of potential PBI candidates. Prospective study is needed to further define the true utility of MRI in this setting.