Stanford Medicine surgeons have adopted a new imaging technology designed to reduce the need for additional surgeries after lumpectomy, becoming the first in the United States to implement the approach.

The LumiSystem, cleared by the U.S. Food and Drug Administration in 2024, uses a fluorescent dye to illuminate cancer cells that may remain after tumor removal. This allows surgeons to immediately identify and excise any residual cancer during the initial operation, potentially sparing patients from a second procedure.

Lumpectomies, a standard treatment for early-stage breast cancer, aim to remove tumors while conserving healthy tissue. Postoperative pathology determines whether the excised tissue’s margins are cancer-free, but this review typically takes days and examines only a fraction of the tissue surface. When margins are positive, additional surgery is often recommended.
“With lumpectomy, we always strive to remove the entire tumor, but it’s not always possible to judge the tumor’s edges during the operation,” said Irene Wapnir, M.D., professor of surgery at Stanford Medicine and a senior investigator in a pivotal trial of the technology. “This system lets us scan the cavity immediately after tumor removal to look for any remaining cancer.”

The LumiSystem uses a handheld scope to detect fluorescence activated by enzymes specific to tumor cells or associated inflammatory cells. Surgeons inject the dye about two hours before surgery and use the device to scan the tumor site once the mass has been removed. The process adds an average of five to seven minutes to the procedure, Wapnir said.

In a national study of 357 patients, the technology identified residual cancer in 14.5% of cases where margins were initially positive, and in some instances, it detected cancer missed by pathology alone.

Stanford offers the system to eligible patients, primarily those with single, untreated breast tumors. Wapnir noted that while most patients are eager to opt in, the hospital is transparent about its limitations and is currently evaluating its use in more complex cases.

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