A test for breast cancer tool: Is it worth it?

Next month, Thomas G. Frazier will sit down with colleagues at Bryn Mawr Hospital's Comprehensive Breast Center and unseal the results of a blind study for Dune Medical's MarginProbe.

The four-month, 30-patient study is the second conducted at Bryn Mawr on the new diagnostic tool designed to help breast cancer surgeons determine - within minutes - whether they have removed all the malignant tissue during a lumpectomy and reduced the need for later surgery.

If the second study is positive, the device could become a key tool for breast cancer surgeons at Bryn Mawr and elsewhere.

Frazier wants to know whether the MarginProbe reduces the number of second surgeries enough - either alone or with other technologies - to warrant buying it.

"Any time you can do one surgical procedure instead of two, it's a good thing to investigate," said Frazier, the center's medical director.

"Nothing is 100 percent, so this isn't 100 percent, but it is a better option than what is available," said Diane Robertson, director of the health technology assessment service for the ECRI Institute in Plymouth Meeting.

During a lumpectomy, the surgeon removes the tumor and surrounding tissue. The specimen's margins are marked with a special ink and sent to pathology for examination. Margins are the distance between the tumor and the edge of the surrounding normal tissue.

The results can take several days, during which patients are sent home to heal. A positive report means cancer was found in "the ink," or margins, requiring a second surgery.

For years, the second surgery rate on lumpectomies has been "a dirty little secret that surgeons have kept hidden in the closet," says Bill Gearhart, vice president of marketing and sales for the Israeli company that makes the device. "The typical number is 25 percent."

The MarginProbe received FDA approval in December 2012. The current model looks like a vintage Macintosh computer mounted on top of a standalone ATM pedestal. The probe - think electric toothbrush on steroids - is connected to the console by a cable. Gearhart expects FDA approval for a lighter, more portable unit in January.

Cancer cells and normal cells emit different electrical signals. The device uses an algorithm calibrated for breast tumors and radio-frequency spectroscopy to detect differences.

After removing the tumor, the surgeon moves the probe over the surface of the specimen. Sensors take radio-frequency measurements. The device never touches the patient, who remains sedated.

In three to five minutes, the surgeon can find any remaining cancer, Gearhart says. If any is detected, the device beeps and a red bar appears on the screen. If the tissue is cancer-free, the bar is blue.

When cancer cells are detected, the surgeon can immediately remove more tissue and redo the test, possibly saving the patient from a future surgery.

One study found the device prevented 60 percent of second surgeries. Another trial, in February in Germany, included 42 patients and found a 56 percent reduction.

Gearhart said false positives ranged between 13 percent and 30 percent, depending on the density of the breast tissue. The machine costs $40,000. The probes are about $1,000 to $1,200 apiece and can be used only once.

In 2011, Bryn Mawr took part in the first, 500-patient study, which helped Dune win FDA approval. The hospital used the probe on 13 patients and reported a 23 percent decrease in repeat surgeries.

This time, the hospital more than doubled its sample size. And Bryn Mawr has added new technology. One is called radioactive seed tumor localization.

When a breast-tumor biopsy is done, a titanium clip is placed where the tumor is suspected. If the biopsy is negative, the clip isn't removed. If the biopsy is positive, the patient has a radioactive seed implanted so the surgeon can find it. The seed can be placed up to five days before surgery.

The seed and clip are removed with the tumor.

When the specimen is removed, the surgeon can X-ray it in the OR and within a minute see whether there is a satisfactory margin around the tumor. The surgeon also feels around the margin and in the cavity for any tumor.

Whether Bryn Mawr buys the MarginProbe will probably come down to numbers - both second surgeries saved and cost.

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