Wednesday, September 01, 1999
A new tool in the search for breast cancer
Sentinel node biopsy a less-invasive technique
BY SUE MacDONALD
The Cincinnati Enquirer
One of the most common surgical procedures for determining whether breast cancer has spread to the lymph nodes may be outdated in a matter of years.
Instead of removing up to 30 or more lymph nodes under a woman's arm and searching for cancer in each of them, specialists say they're encouraged by the use of a new technique that identifies only one or two gate-keeper lymph nodes that are more likely to trap stray cancer cells.
The technique, called sentinel node biopsy, allows doctors to perform extensive tests on those few nodes to confirm or rule out the spread of cancer.
It also involves less invasive surgery and fewer side effects — especially numbness and swelling of the arm — than the current method of removing clusters of lymph nodes under a patient's arm.
It also ensures that women whose cancer has spread will get potentially life-saving follow-up treatment while those whose cancer remains in the breast will be spared unnecessary treatment.
“I think it's highly likely that this will be the future of breast cancer care,” says Dr. Andrew Lowy, chief of cancer surgery at the University of Cincinnati Medical Center and the Barrett Cancer Center. “If you can do it accurately, the predictability of this technique is 95 percent.”
And detecting whether breast cancer has spread to other organs “is what ultimately determines who lives and who dies of breast cancer,” writes California surgeon Dr. Susan Love in Dr. Susan Love's Breast Book (Addison-Wesley; $17).
However, Dr. Lowy and other cancer specialists urge women not to rush out and demand the procedure of their doctors now because:
• The biopsy technique is new and still being developed and refined.
• Not all doctors have been trained to do the technique accurately and properly. Its effectiveness depends on a surgeon's skill and accuracy at finding the sentinel nodes.
• Despite promising results, no long-term studies have been done to show it works better than the old biopsy technique. Only now is a national comparative study getting under way, and UC hopes to participate.
“Use and demand of this technique is truly exploding across the country, yet the whole field is very young,” says Dr. David Ollila, surgeon at the University of North Carolina-Chapel Hill School of Medicine. “The first description of the technique in breast cancer patients was less than five years ago.”
If the biopsy is done by an untrained, unskilled surgeon, the real risk is missing cancer that has spread, not finding cancer that isn't there, Dr. Lowy says.
In best-case scenarios, sentinel-node biopsy can accurately identify women who need chemotherapy and follow-up treatment and rule out those who don't, because it determines whether cancer has spread beyond the breast.
Women also avoid the side effects of surgical lymph node removal, which can include numbness, swelling, lack of sensation and limited range of motion in the arm.
In worst-case scenarios, a poorly performed technique will wrongly tell a woman her body is cancer-free. Such a finding — a “false negative” — means she may not be offered critical and potentially life-saving follow-up treatment for the spreading cancer, will have a shorter survival and poorer prognosis.
“I think it's important for patients to understand that this technique is not the standard,” Dr. Lowy says. “If they're interested in having it, they really need to question the surgeons' experience.”
It was only in 1992 that sentinel node biopsy was introduced. Until recently, it was used to determine whether skin or testicular cancer had spread to lymph nodes, Dr. Lowy says. In October, 1998, a study in the New England Journal of Medicine indicated it also worked for breast cancer.
Dr. Lowy says the theory behind the procedure lies in how lymph fluid circulates through lymph vessels, which are similar to but smaller than blood veins.
The clear lymph fluid bathes the body's cells and tissues by flowing in identifiable channels and directions, carting infection-fighting substances to healthy tissue and hauling away waste.
At various strategic locations, small lymph nodes filter out foreign particles and produce lymphocytes to fight infection. These nodes can range in size from 3 millimeters to about 1 centimeter, and they are clustered in the armpit, neck and groin.
“If you have a tumor in a particular place, the cancer will not metastasize (spread) to a general area,” he says. “Instead of going randomly to any one of the many lymph nodes in your arm, it will first go to one or two specific nodes drained by that particular lymph channel.”
Doctors are finding they can map those drainage channels and then use special dyes and markers to identify the sentinel nodes.
Once removed, the nodes can be thoroughly examined and tested by a pathologist for signs of cancer. Breast cancer is rated in stages of severity, depending on where the cancer has spread. The stage determines what kind of treatment is recommended.
“Hopefully, this type of biopsy will improve the staging and get appropriate treatment for women who need it,” Dr. Lowy says.
In the future, doctors think the same biopsy technique might be applied for colon cancer, other forms of skin cancer and some female genital cancers.
CHOOSING A SURGEON
Because sentinel node biopsy is a fairly new technique, it's important to find a surgeon who knows how to do it accurately, according to cancer specialists. Questions to ask include:
• What is your training, background and experience with sentinel node biopsy for breast cancer?
• How many sentinel node biopsies have you done?
• What is your false negative rate? (an indication of whether the doctor misses cancers that truly exist).
• Do you practice at a major cancer treatment center?
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