Administering a local anesthetic decreases the pain patients feel during an important procedure for staging breast cancer, but does not interfere with the surgeon’s ability to determine tumor presence, according to a new study by University researchers in the October issue of the Journal of Nuclear Medicine Technology.
In the past, this procedure — called breast lymphoscintigraphy — has been an integral yet unpleasant part of breast cancer staging. Many breast cancer patients go through this painful lymph node assay, in which a low-activity radioactive substance is injected and absorbed by the lymph nodes. Surgeons then extract and dissect the lymph nodes with the highest levels of radioactivity, searching for signs of metastasizing cancer, which often spreads to the lymph nodes first.
The administration of this radioactive substance “can be quite painful,” said Richard Noto, director of the Division of Nuclear Medicine at Rhode Island Hospital, associate clinical professor at the Alpert Medical School and one of the authors of the study.
“We’ve had comments from patients that one of the worst parts of having breast cancer … was coming to Nuclear Medicine and getting lymphoscintigraphy done,” said Don Yoo, director of nuclear medicine at Miriam Hospital and associate professor of diagnostic imaging, who worked on the study alongside Noto. Yoo said the treatment is painful because the radiopharmaceutical is acidic. Injections occur at the skin surface, where there are many sensitive nerve endings.
“Some patients really had excruciating pain while they were having the procedure,” Yoo said. The researchers tested administering buffered 2 percent lidocaine before the radiopharmaceutical to decrease the patients’ discomfort. “What we do is very minor, but obviously we want to try to do anything that will help try to improve that experience,” he added.
Noto said in designing the study, the researchers had to consider whether the decreased pain caused by administering lidocaine would offset the additional discomfort caused by another needle stick. In addition, he added, they wanted to ensure “the surgeons would be able to detect the same lymph nodes and the same number” of nodes.
But “lidocaine is what we use in hospital settings so often for minor interventional procedures, and it’s so well tolerated,” Yoo said. “It’s kind of a standard (anesthetic) for so many of these procedures that’s easy to do, widely accessible and pretty cheap.”
Previously, some clinicians had expressed doubts that injecting lidocaine could preserve visualization quality, Noto said. Since the lidocaine is injected under the surface of the skin in the same location as the radiopharmaceutical, the worry was that the lidocaine would prevent the radioactive substance from reaching the patient’s lymph nodes, he added.
The researchers pushed ahead with the study, hoping that their hypothesis would be proven correct.
Forty-nine patients participated in the random-assignment study, Yoo said. Both patients who received lidocaine and those who did not rated their pain levels before and after the procedure on a standardized scale, and the researchers compared changes from the baseline to derive the study result.
Both authors acknowledged the subjective nature of their measurements.
“There was quite a bit of variability, as you would expect,” Noto said, adding that the researchers took the average values of the data and largely disregarded the variability from one patient to another. Yoo said the study aimed to minimize subjectivity by using patients of similar ages.
“We tried to be as objective as possible, but everyone does have a different level of pain” tolerance, he said.
Martha Mainiero, professor of diagnostic imaging and director of the Anne C. Pappas Center for Breast Imaging at Rhode Island Hospital, who was not involved in the study, emphasized the objective nature of the study in an email to The Herald. “The prospective, randomized nature of the trial is a strength of the study,” she wrote.
At the study’s conclusion, the researchers found that the lidocaine injection did indeed decrease pain levels in patients by statistically significant levels.
The procedure “also did not change the number of lymph nodes that on average were seen,” Noto said.
“It was a win-win situation for both things we were trying to evaluate,” Yoo said.
Noto and Yoo have already implemented the protocol of injecting lidocaine before breast lymphoscintigraphy in their own practices, Noto said.
“The results are pretty consistent and convincing both in terms of the pain result and the absence in any change in terms of the lymph node optics,” he added.
Yoo said many practices were already using lidocaine before the procedure, but that this study represents the first concrete proof that the protocol is effective.
“This article gives scientific validity to a technique that has been utilized inconsistently across the country,” Mainiero wrote. “The implication is that the technique of using lidocaine for breast sentinel lymph node injection should become standard.”
Noto added that this study constitutes an important “step forward” in improving the patient experience.
“There is no longer a good reason to not give a patient lidocaine before doing the procedure,” Yoo said.
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