When early-stage breast cancer is removed, the lymph node closest to the cancer – called the sentinel node – often is removed and sent to a pathologist for evaluation. Removing just this one node is called sentinel node biopsy or sentinel node dissection.
If cancer cells are in the sentinel node, it means the cancer has spread beyond the breast. Until recently, doctors thought that more treatment was necessary to reduce the risk of the cancer coming back (recurrence), including removing other underarm lymph nodes (called axillary node surgery/dissection).
But a practice-changing study, called the ACOSOG Z-11 trial, found that women diagnosed with early-stage disease with one or two positive sentinel nodes who have lumpectomy and radiation do just as well as women who have axillary node surgery.
In 2014, the American Society of Clinical Oncology (ASCO) put out new guidelines on sentinel lymph node surgery, based in part on the results from ACOSOG Z-11 trial. ASCO is a national organization of oncologists and other cancer care providers. ASCO guidelines give doctors recommendations for treatments and testing that are supported by much credible research and experience.
Among other directives, the new guidelines say:
- Women diagnosed with early-stage breast cancer with one or two positive sentinel nodes who plan to have lumpectomy plus whole-breast radiation don’t need axillary node surgery.
- Women who have one or more positive sentinel nodes and plan to have mastectomy with no radiation should be offered axillary node surgery.
In this study, the researchers wanted to know if most doctors were following this recommendation. Encouragingly, most women diagnosed with early-stage breast cancer with one or two positive sentinel nodes who plan to have lumpectomy and radiation are not having more axillary nodes removed.
The study was published online on March 25, 2015 by the Journal of the American College of Surgeons. Read the abstract of “Impact of the American College of Surgeons Oncology Group Z0011 Randomized Trial on the Number of Axillary Nodes Removed for Patients with Early Stage Breast Cancer.”
The researchers looked at the records of more than 74,300 women who were diagnosed between 1998 and 2011 with early-stage breast cancer that was 5 cm or smaller in size (smaller than 2 inches), had negative margins, and had two or fewer positive sentinel nodes. All the women had lumpectomy plus whole-breast radiation therapy.
The researchers found that women who had only sentinel lymph surgery more than doubled, from 23% in 2009 (the year before the ACOSOG Z-11 study results were published) to 56% in 2011, the year after publication.
Women were more likely to have axillary lymph node surgery if the women or the cancer had any of the following characteristics, which tend to make a cancer have a higher risk of recurrence:
- a woman was younger than 50
- a woman was black
- the cancer was triple-negative (estrogen-receptor-negative, progesterone-receptor-negative, and HER2-negative)
- the cancer was larger than 3 cm
- there were two or more positive nodes
- the cancer was grade 3
The researchers said it may be that some doctors aren’t comfortable only doing a sentinel node biopsy on women diagnosed with early-stage breast cancer with a higher-than-average risk of recurrence, even though the recommendations say these women don’t need axillary lymph node surgery.
The researchers also looked at the records of more than 400,000 women diagnosed with early-stage disease who didn’t meet the criteria for having only sentinel node surgery. They found:
- 22% of women who had mastectomy in 2011 had only sentinel node surgery
- more than 50% of women diagnosed with cancers larger than 5 cm who got no or partial-breast radiation therapy had only sentinel node surgery
The results of this study are both encouraging and concerning. It’s encouraging that most of the women eligible to have only sentinel lymph node surgery are having it. Women who have only sentinel node surgery and not axillary node surgery have a much lower risk of lymphedema. Lymphedema is the build-up of fluid in the soft tissues of the body, most often the arm and hand in people who’ve had breast cancer surgery, but also the breast, underarm, chest, trunk, and back. Besides swelling, lymphedema also can cause arm weakness and numbness, as well as shoulder pain.
Still, it’s concerning that many women who really aren’t eligible to have only sentinel node surgery are having it. If cancer cells are left in the lymph nodes and not treated with radiation therapy, it could increase the risk of recurrence.
If you’ve been diagnosed with early-stage breast cancer, sentinel node biopsy may be done as part of your surgery. If cancer cells are found in the sentinel node, you and your doctor will consider all the details of your situation, including your age, your general health, the characteristics of the cancer, and your specific preferences when deciding on a treatment plan.
You can learn more about lymph node surgery by visiting the Breastcancer.org Lymph Node Removal pages.