MRI predicts breast cancer tumor size; identifies candidates for surgery

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MRI may be an important imaging modality in assessing tumor size in women with breast cancer, both before and after neoadjuvant chemotherapy, to identify candidates for breast conservation surgery, according to a paper in the November issue of the Journal of Surgical Oncology.

“MRI helps predict response to neoadjuvant therapy in breast cancer better than other imaging modalities,” said Mehra Golshan, MD, FACS, director Breast Surgical Services, Brigham and Women’s Hospital, and one of the authors of the report.

Sixty-eight patients with stage I, II and III breast cancer were enrolled in three neoadjuvant chemotherapy trials between June 2004 and June 2006 at the Dana Farber Cancer Institute and Brigham and Women’s Hospital in Boston.

As part of the trials, the patients underwent MRI, ultrasound and physical examination before neoadjuvant treatment and for two weeks after. Once all three trials were completed, patients then underwent another MRI examination, at least two weeks before surgery.

Investigators reviewed the imaging studies performed on these patients prior to surgery to determine whether MRI, ultrasound or physical exam best predicted final pathologic tumor size.

Of the 68 patients with MRI data, the correlation coefficient (r) of MRI to pathologic size of tumor was 0.749. Among the 52 patients who had an ultrasound assessment, the correlation of ultrasound to pathology was r = 0.612. Sixty-two patients had physical exam data, and the correlation of examination to pathology size was r = 0.439.

MRI correctly predicted 8 of 11 complete responders and accurately evaluated the size of non-responders to neoadjuvant therapy (r = 0.869). In 11 percent of cases, MRI underestimated tumor size by more than 1 cm in 52 patients, compared with 22 percent in 34 for ultrasound and 32 percent for physical examination.

According to the study, there is “evidence suggesting the superiority of MRI in accurately assessing the preoperative tumor size compared to conventional imaging modalities in patients undergoing neoadjuvant chemotherapy.”

Results showed that “MRI was more accurate than physical examination or breast ultrasonography in assessing preoperative residual tumor size.” Increasing the accuracy of estimates of tumor size before and after administering neoadjuvant treatment may help to select appropriate patients for breast conservation surgery, according to the findings.