Sentinel node biopsy considered for breast

Is it better than full axillary node dissection?

(Editor’s note: This is the third in a four-part series highlighting innovative outpatient surgery procedures. In the previous two issues, we’ve covered cosmetic procedures and pain management procedures. Don’t miss next month’s issue, which will highlight another cutting-edge procedure that can yield profits for your same-day surgery program.)

At what point should you expand beyond the traditional approach for a procedure and add a new operation as an option? This is the question many same-day surgery managers are struggling to answer regarding sentinel lymph node biopsy for breast cancer. To assist readers, we’re highlighting how Johns Hopkins Outpatient Center in Baltimore is approaching the dilemma and we’re telling you about the latest published research on the topic. We’ll also preview some upcoming studies. (See story, p. 23.)

Sentinel lymph node biopsy is a diagnostic test used to determine the status of regional lymph nodes.1 The question is whether this procedure can replace the traditional axillary node dissection. A recent report in the New England Journal of Medicine reported that "it is feasible to perform the sentinel-node procedure successfully in a variety of surgical settings."2

At Johns Hopkins, the new approach is being studied in conjunction with using the traditional approach. The study began in January 1998, and 67 patients have undergone sentinel node biopsy in addition to axillary node dissection. Study leaders hope to prove that the approach reduces morbidity such as lymphedema.

Johns Hopkins study leaders want to conduct a significant number of cases before they can fully evaluate all the technical issues such as accuracy, says Mary Donnelly Strozzo , CRNP, MPH, MS, adult nurse practitioner at The Johns Hopkins Breast Center, which is part of Johns Hopkins Outpatient Center.

Here’s how the sentinel lymph node biopsy is performed at Johns Hopkins: First, the tumor area is identified with ultrasound or by mammography. Next, a localization procedure is done in which needles are placed to physically identify the tumor. Patients are transferred to the nuclear medicine department because, in Maryland, only those staff can inject a nuclear isotope.

"It takes an hour for the radioactive material to travel from the tumor site to the first node, which we identify as the sentinel node," Strozzo says.

Patients go to surgery, where they have the same incisions as with the traditional axillary node dissection. However, a gamma probe acts as a Geiger counter and identifies where the radioactive material has traveled, which is the sentinel node. The sentinel node is confirmed by counting for radioactive activity and sent to pathology for microstaging and other tests. However, since Johns Hopkins hasn’t completed its study, the patient undergoes a traditional axillary node dissection at that point, which involves removing a sampling of the lymph nodes.

Beware of false-negative rate

The biggest concern regarding conversion to sentinel node biopsy appears to be the false-negative rate. Strozzo cites the "sounding board" report that accompanied the study in the New England Journal of Medicine. In the sounding board, physicians reported that the false-negative rate is the most important factor regarding sentinel lymph node biopsy because it could lead to incorrect treatment.1

Thus far, the experience at Johns Hopkins has been positive, Strozzo says. "Our false-negative rate seems to be quite low. And that’s the whole idea. Will the accuracy be just as good?"

However, in addition to studying this rate, managers who want to add the procedure need to consider the following concerns and contraindications:

o There is a learning curve for staff.

"One of problems with finding out when you can go to the procedure is making sure all staff are proficient," Strozzo says. Nuclear medicine or other staff need to learn a new skill of injecting the radioisotope, and surgeons need to become adept at using the gamma probe to identify where the material was transported.

The study in the New England Journal of Medicine acknowledges that sentinel node biopsy is a technically challenging procedure, "and the success rate varies according to the surgeon and the characteristics of the patient."2

o Patients have to be at facility earlier.

Instead of arriving two hours prior to surgery, patients who are participating in the sentinel lymph node study at Johns Hopkins are asked to arrive four hours prior to surgery to allow time for the nuclear isotope to be injected and travel to the first node.

"That’s usually the main obstacle for people in the study," Strozzo says.

o Patients or staff might be concerned about radiation from the nuclear isotope.

Patients have expressed concern about the level of radiation exposure, Strozzo says.

"What we’re saying is that it’s equal to a standard chest X-ray, or it’s equal to 1/20 dose of a bone scan," she says. "People seem familiar with those, and they aren’t concerned once we tell them about the low level of radioactive material. "Staff haven’t expressed any concerns, Strozzo reports.

Contraindications for sentinel lymph node biopsy include patients who have multifocal cancer within the breast. "If you have various focuses, the cancer may not go to just one node, but several," Strozzo says. And because radioactive material is used, patients can’t be pregnant, she says.

The procedure isn’t performed if there is a high degree of suspicion that positive nodes will be found, Strozzo says. "If we felt any lymph nodes were enlarged, you probably have positive nodes."

Sentinel lymph node biopsy isn’t the answer for every patient, she emphasizes, "but for grade 1 or grade 2 [cancer], with a low risk of positive nodes, it appears this is what we should do in the future." If the nodes are clinically negative, it might be the appropriate approach for grade 3 also, she adds.

References

1. McMasters KM, Giuliano AE, Ross MI, et al. Sentinel-lymph-node biopsy for breast cancer — not yet the standard of care. N Engl J Med 1998; 339:990-995.

2. Krag D, Weaver D, Ashikaga TA, et al. The sentinel node in breast cancer. N Engl J Med 1998; 339:941-946.