Further testing using breast-specific gamma imaging (BSGI) may find additional cancer in the same or opposite breast, with fewer false positives, in women recently diagnosed with breast cancer, according to a study published in the February issue of the American Journal of Surgery.
BSGI, a molecular breast imaging technique, is a follow-up to mammography that can see lesions independent of tissue density and discover early stage cancers. With BSGI, the patient receives a pharmaceutical tracing agent that is absorbed by all the cells in the body. Due to their increased rate of metabolic activity, cancerous cells in the breast absorb a greater amount of the tracing agent than normal, healthy cells and generally appear as "hot spots" on the BSGI image.
"The research is important because it helps clarify the role of BSGI in newly diagnosed breast cancer patients. We have found that these women can have more extensive disease that is not detected by mammography or ultrasonography. This is especially helpful in patients with dense breast tissue where additional evaluation of the remaining breast tissue is necessary," said Nathalie Johnson, MD, general surgeon and surgical oncologist at Good Samaritan Hospital, Portland, Ore.
Johnson and her team conducted a retrospective review from two Portland, Ore. community-based breast imaging centers of newly diagnosed breast cancer patients in whom BSGI (Dilon 6800 Gamma Camera)was performed as part of the imaging work-up.
A total of 138 patients (69 invasive ductal carcinoma, 20 invasive lobular carcinoma, 32 ductal carcinoma in situ, and 17 mixtures of invasive ductal carcinoma, invasive lobular carcinoma, or ductal carcinoma in situ and other) were reviewed. Twenty-five patients had a positive BSGI study at a site remote from their known cancer or more extensive disease than detected from previous imaging.
Fifteen patients were positive for a synchronous or more extensive malignancy in the same or contralateral breast. Five patients had benign findings on pathology, five benign on ultrasound follow-up (false-positive rate, 7.2 percent). Findings converted seven patients to mastectomy, one patient to neoadjuvant chemotherapy, and seven patients were found to have previously undetected contralateral cancer. The positive predictive value for BSGI was 92.9 percent.
BSGI detected additional or more extensive breast cancer in the same or opposite breast in 10.9 percent of newly diagnosed patients according to the study.
Only 7.2 percent incurred an additional work-up. "BSGI provides accurate evaluation of remaining breast tissue in newly diagnosed breast cancer patients with few false-positive readings," the authors concluded.