Study: Breast Biopsy Getting Ahead of Itself
Investigational technique now routine, and some fear prematurely
TUESDAY, Oct. 14, 2003 (HealthDayNews) -- An investigational procedure called a sentinel node biopsy is now being routinely performed on women with early-stage breast cancer, but some experts say this may be premature.
While it involves less surgery than the standard procedure to detect how far cancer has spread, adopting the investigational method too soon may compromise ongoing clinical trials, say experts writing in the Oct. 15 issue of the Journal of the National Cancer Institute.
"This is a complex issue," says study author Dr. Stephen B. Edge, a physician at Roswell Park Cancer Institute in Buffalo, N.Y. "On the one hand, there is an enormous body of literature showing the technique of sentinel node biopsy is accurate. On the other hand, there is not [yet] a full head-to-head comparison with full lymph node dissection."
In the standard procedure, axillary node dissection, the lymph nodes under the arm on the same side as the cancer are removed so the doctor can evaluate any spread of the cancer. If it has spread, more treatment, such as chemotherapy, is ordered.
But the standard procedure results in about one-fourth of women developing pain or chronic swelling of the arm, called lymphedema, according to the American Cancer Society.
So the newer procedure, sentinel node biopsy, involves identifying the first -- or sentinel -- node under the arm, and testing it. The theory is that if the breast cancer is going to spread, it will travel first to the first node. If the cancer is not in that node, additional surgery can be avoided. If it has spread there, the surgeon can then do the axillary node dissection.
"With sentinel node biopsy, the incidence of lymphedema is 1 percent or less," Edge says.
Edge and his colleagues examined the pattern of how the new technique was used, evaluating 3,003 women with stage I or II breast cancer who had a variety of procedures done at one of five comprehensive cancer centers in the United States between 1997 and 2000, the years the new technique was becoming more widespread.
Overall, the sentinel node biopsy alone was used in 13 percent of women, sentinel node and axillary node dissection in 22 percent, axillary node dissection in 59 percent and no axillary surgery in 6 percent.
The use of the new technique in the 1,763 women with stage 1 cancers treated with breast-conserving surgery increased over the study period from 8 percent in 1997 to 58 percent at the end.
"It appears that the surgical teams at these centers, reviewing the available evidence, felt they could accept it [the new procedure] as the standard of care," Edge says.
And he questions whether that might bias the results of the ongoing clinical trials comparing the techniques.
But the counterargument, he acknowledges, is that putting off the use of sentinel node biopsy while awaiting the results of ongoing clinical trials -- expected in 2007 -- means more women would suffer side effects such as lymphedema.
In an editorial accompanying the study, Dr. David N. Krag, a cancer surgeon at the University of Vermont College of Medicine in Burlington, tries to allay the concerns, noting that many of them have already enrolled the required number of women or are close to doing so.
"It's hard for me to agree with that conclusion because these studies are essentially done," he says.
In a series of commentaries printed in the same issue, experts also caution women who have not yet gone through menopause to be fully informed about the potential harms and benefits of undergoing mammography.
Some studies, for instance, have found a higher death rate from breast cancer among screened women aged 40 to 49 than among unscreened women. Another expert, however, says that evidence is weak but that screening younger women may also result in high numbers of false-positive results and unnecessary biopsies.