Abstract
BackgroundMammography and ultrasound are the gold standard imaging techniques for preoperative assessment and for monitoring the efficacy of neoadjuvant chemotherapy in breast cancer. Maximum accuracy in predicting pathological tumor size non-invasively is critical for individualized therapy and surgical planning. We therefore aimed to assess the accuracy of tumor size measurement by ultrasound and mammography in a multicentered health services research study.MethodsWe retrospectively analyzed data from 6543 patients with unifocal, unilateral primary breast cancer. The maximum tumor diameter was measured by ultrasound and/or mammographic imaging. All measurements were compared to final tumor diameter determined by postoperative histopathological examination. We compared the precision of each imaging method across different patient subgroups as well as the method-specific accuracy in each patient subgroup.ResultsOverall, the correlation with histology was 0.61 for mammography and 0.60 for ultrasound. Both correlations were higher in pT2 cancers than in pT1 and pT3. Ultrasound as well as mammography revealed a significantly higher correlation with histology in invasive ductal compared to lobular cancers (p < 0.01). For invasive lobular cancers, the mammography showed better correlation with histology than ultrasound (p = 0.01), whereas there was no such advantage for invasive ductal cancers. Ultrasound was significantly superior for HR negative cancers (p < 0.001). HER2/neu positive cancers were also more precisely assessed by ultrasound (p < 0.001). The size of HER2/neu negative cancers could be more accurately predicted by mammography (p < 0.001).ConclusionThis multicentered health services research approach demonstrates that predicting tumor size by mammography and ultrasound provides accurate results. Biological tumor features do, however, affect the diagnostic precision.
Highlights
Mammography and ultrasound are the gold standard imaging techniques for preoperative assessment and for monitoring the efficacy of neoadjuvant chemotherapy in breast cancer
Four thousand two hundred ten patients (64.3 %) showed pN0 status. 10.8 % of the tumors were graded as G1, the majority of tumors were G2 (61.8 %) and 27.3 % were G3 carcinomas. 14.4 % of the tumors were hormone receptor (HR) negative. 14.8 % of the tumors overexpressed HER2
A Bland-Altman plot (Fig. 1a) indicates that measurement differences were proportional to tumor size with invasive lobular tumors being over-represented among tumors that are underestimated by ultrasound: Among 198 tumors underestimated by more than 20 mm, 68 (34 %) were invasive lobular cancers
Summary
Mammography and ultrasound are the gold standard imaging techniques for preoperative assessment and for monitoring the efficacy of neoadjuvant chemotherapy in breast cancer. We aimed to assess the accuracy of tumor size measurement by ultrasound and mammography in a multicentered health services research study. Distinct biological subgroups of breast cancer show significantly different tumor growth and prognosis as well as therapeutic options [1]. Using cDNA microarray analysis, Perou et al defined different biological subgroups of breast cancers with impact on tumor biology and clinical appearance [1]: Luminal A and B breast cancers as well as HER2/neu positive and basal like breast cancer. Gene expression profiling is not yet part of routine tumor analysis But hormone receptor expression, HER2/neu overexpression and proliferation markers represent surrogate markers for biological breast cancer subgroups
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