Sentinel node biopsy reduces complications of breast surgery.
Good news for women with breast cancer who have only one or two positive lymph nodes: a new study suggests they may be able to skip more invasive surgery that carries a risk of chronic pain, swelling and limited range of motion in the shoulder.
During the 2010 meeting of the American Society of Clinical Oncology (ASCO) in June, researchers produced the strongest data yet suggesting that women with one or two positive lymph nodes who kept their axillary nodes fared just as well as those who had multiple nodes removed in axillary node dissection.
“This is viewed as a practice-changing study,” says Marilyn Leitch, MD, a breast cancer surgeon at the University of Texas Southwestern Medical Center in Dallas and one of the study’s authors. “It is a major shift to take this leap,” Leitch says.
Doctors and patients alike are wary of leaving axillary nodes behind without assurances they are free of cancer. That’s because, when breast cancer spreads, malignant cells use the body’s lymphatic system as their own personal highway.
The first stops are the grape-shaped lymph nodes, which sit in bunches in the armpit and in other patches throughout the body. The lymph nodes are part of the body’s immune system, trapping bacteria, stray cancer cells and other harmful invaders. Each node connects to a system of channels that carries lymphatic fluid in the same way arteries and veins transport blood.
Much about a woman’s diagnosis depends on an assessment of the lymph nodes. After a cancer diagnosis, doctors use a dye or radioactive tracer to identify and remove the node or nodes in which the cancer is most likely to head first—the sentinel node—for testing to determine if cancer cells are present.
If the sentinel node shows no signs of cancer, it’s likely that the cancer has not yet spread. This means patients are spared a full node dissection. If just one or two nodes contain cancer cells, the meaning is less clear.
To be cautious, surgeons usually will go ahead and remove more than a dozen other nearby nodes, called the axillary nodes, on the chance that they, too, have collected cancer cells. But over the past decade, experts have questioned whether the removal of axillary nodes is really necessary when the sentinel node (or nodes if two are involved) is positive. New data now provide the strongest support yet for the idea of leaving axillary nodes untouched when only one or two sentinel nodes test positive.
In addition to the study released at ASCO, other data released this summer offers reassurance to what is now a standard approach of leaving the axillary nodes when the sentinel nodes do not show any traces of cancer. While data up to now have supported the practice of leaving the axillary nodes, the newest study is the most definitive so far, says Thomas Julian, MD, of the Allegheny General Hospital in Pittsburgh and the study’s co-author. “This nails the lid on the box,” he says. “When sentinel nodes are negative, you don’t need to take any more axillary nodes out.”
Taking out lymph nodes would not be such a dilemma if the surgery did not have the potential for serious consequences. The side effects aren’t life threatening but can profoundly affect a woman’s quality of life. With lymph nodes gone, the normal circulation of lymphatic fluid gets disrupted. This can lead to lymphedema, a condition that can result in persistent pain, swelling, numbness, tingling and a restricted range of motion in the shoulder (see "Limiting Lymphedema").
In the future, fewer women may need to face that risk, according to the data released at ASCO. The research involved 891 women with one or two positive nodes who were randomly assigned to either sentinel and axillary node removal or sentinel node removal alone. All patients received whole-breast radiation. After five years, the survival rates for both groups were similar: 91.9 percent for those who underwent axillary node removal and 92.5 percent for those who did not. The likelihood of breast cancer recurrence in the breast at five years was also similar at 3.7 percent for those who had axillary node removal and 2.1 percent for sentinel node removal only.
Given these numbers, Leitch says, women with only one or two positive nodes should be told that skipping axillary removal is a realistic choice. “I think it’s a discussion that a surgeon has to have,” she says. “I think many people are convinced, myself included, that this is reasonable.”
et some surgeons still remain hesitant. “It’s a complicated issue,” says David Krag, MD, a surgeon at the University of Vermont College of Medicine. Krag points out that the study started in 1999 with a goal of enrolling 1,900 women—the number determined to have the statistical power needed to detect even small, but real differences in survival. The data presented this summer involved only about half that number, which weakens the confidence that the results are accurate, he says. “I think we’re still left with the question,” he says. The women in the study will continue to be followed for up to 10 years, important because local recurrences can occur up to five or 10 years later. It may be too early to make conclusions about this trial.
Data presented at the meeting on node-negative women found that, after an average of eight years, a full axillary dissection did not affect survival, but it did greatly increase the side effects in the affected arm.
What is no longer in question, Krag says, is what to do for the three-quarters of women who do not have sentinel lymph node involvement. Data presented at the meeting on node-negative women found that, after an average of eight years, a full axillary dissection did not affect survival, but it did greatly increase the side effects in the affected arm. When it comes to women with clean sentinel nodes, he says, “the case is closed.”