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Combined Optical and Molecular Imaging
Could Guide Breast-Conserving Surgery

Breast-conserving surgery (BCS) is the primary treatment for early-stage breast cancer, but more accurate techniques are needed to assess resection margins during surgery to avoid the need for follow-up surgeries. Now, in a first-in-human study, British researchers have provided a possible solution using Cerenkov luminescence imaging (CLI), which combines optical and molecular imaging by detecting light emitted by the PET radiotracer 18F-FDG. CLI’s high-resolution and compact imaging equipment make it a promising technology for assessing tumor margins during breast tumor surgery. The study is published in the June issue of the Journal of Nuclear Medicine.

“Currently, approximately one in five women who undergo breast-conserving surgery, also known as lumpectomy, require repeat surgery due to inadequate excision of the tumor during the initial surgical procedure,” explains Arnie D. Purushotham, MD, a professor at King’s College London in the United Kingdom. “By accurately assessing tumor resection margins intraoperatively with CLI, surgeons may be able to completely clear the cancer with a single operation, thereby reducing the number of breast cancer patients requiring a second, or even third, surgical procedure. Ultimately, this could lead to improved patient care and reduced health care costs, if confirmed in larger clinical studies.”

The study included 22 patients with invasive breast cancer. 18F-FDG was injected 45 to 60 minutes before surgery. Immediately after the excision of tumors, specimens were imaged intraoperatively in an investigational CLI imaging system. The first 10 patients were used to optimize the imaging protocol; the remaining 12 were included in the analysis data set. Ten of the 12 patients had an elevated tumor radiance on CLI, and agreement among raters on margin distance was good. Sentinel lymph nodes, which received technetium-99m to facilitate identification, were successfully detected and biopsied in all patients.

18F-FDG CLI is, therefore, a promising, low-risk technique for intraoperative assessment of tumor margins in BCS, Purushotham says. A randomized controlled trial will evaluate the impact of this technique on re-excision rates.

“The feasibility of intraoperative CLI as shown in this study, in combination with the wide applicability of 18F-FDG across a range of solid cancers, provides a stepping stone for clinical evaluation of this technology in other solid cancer types that also experience incomplete tumor resection due to close or involved margins,” Purushotham says. “CLI offers the ability to image clinically approved and widely used PET tracers intraoperatively by using small-sized imaging equipment, thus expanding the field of traditional nuclear medicine.”

Source: SNMMI