Breast-Specific Gamma Imaging Aids ILC Diagnosis

Breast-specific gamma imaging may help identify extent of invasive lobular carcinoma

medwireNews: Patients with invasive lobular carcinoma (ILC) benefit from breast-specific gamma imaging (BSGI) to check for hard-to-detect disease, US researchers suggest.

“Our subgroup of patients with ILC had a higher incidence of synchronous cancer and therefore should routinely be considered for advanced breast imaging”, say Katherine Kelley, from Oregon Health and Sciences University in Portland, and co-workers.

The team reports preoperative BSGI results for 44 ILC patients and 602 patients with invasive ductal carcinoma or ductal carcinoma in situ (IDC group) in JAMA Surgery.

The initial diagnosis was made using mammography and confirmed by biopsy, and BSGI identified these lesions in 90.9% of ILC patients and 80.6% of the IDC group.

In addition, new ipsilateral or contralateral tumours were identified by BSGI in 15.9% of the ILC group and 5.6% of the IDC patients, and these sites were confirmed by ultrasound or magnetic resonance imaging (MRI).

“This finding is clinically significant given that 20% of patients with ILC have contralateral breast cancers, and it suggests that this subgroup should routinely undergo advanced breast imaging”, the researchers write.

Overall, BSGI showed slightly higher sensitivity for detection of previously known or new ILC than IDC, at 88.9% versus 85.1%, but the technique had comparable specificity values for the two tumour types, at 78.7% and 81.8%, respectively.

“In comparing advanced breast imaging tools, such as MRI, we found that BSGI is simple to interpret, better tolerated by patients, and far less costly”, the researchers comment.

However, they note that BSGI use is limited by its greater radiation dosage and lower sensitivity for detection of subcentimeter lesions and axillary node spread.

“Unlike other breast imaging modalities, BSGI reporting is not yet standardized by the Breast Imaging-Reporting and Data System classification”, Katherine Kelley et al observe.

“In addition, very few patients with ILC in our study also underwent MRI, prohibiting any comparisons between BSGI and MRI.”

Reference

Kelley KA, Crawford JD, Thomas K, et al. A comparison of breast-specific gamma imaging of invasive lobular carcinomas and ductal carcinomas. JAMA Surg 2015; Advance online publication 24 June. doi:10.1001/jamasurg.2015.0965

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