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Study Shows Need for Radiation after Mastectomy

Benefits shown for women under age 40, those with four or more positive lymph nodes

March 26, 2013

Written By Nicole Katze, MA, Writer and Editorial Coordinator
Reviewed By Michael C. Stauder, MD

An analysis of previous clinical trials may help define situations with a higher risk of recurrence for women who have mastectomy without radiation therapy. The findings may help clarify when doctors should recommend radiation. 

Study Background 

Radiation therapy is given after surgery for breast cancer to kill cancer cells that may have escaped removal. It is a standard treatment after lumpectomy, surgery to remove only the tumor and some healthy tissue around it, but is not always given after mastectomy, surgery to remove the whole breast. 

Past studies show that in some cases, radiation after mastectomy helps reduce the risk of recurrence for women whose cancers have certain characteristics. The current study looked at women who had mastectomy without radiation, to define what cancer traits suggest radiation therapy may be necessary. 

Study Structure 

Participants in 13 randomized clinical trials had mastectomy without radiation therapy, along with either chemotherapy or hormonal therapy, or both. A total of 8,106 people were followed for an average of 15.2 years. 

Researchers looked for patterns in local recurrence, cancer that returns in the breast; axillary recurrence, cancer that comes back in the lymph nodes of the armpit; and supraclavicular recurrence, cancer that returns in the lymph nodes just above the collar bone. 

Results 

Overall, the analysis showed certain characteristics that predicted a higher chance of all three types of recurrence over 10 years in women who did not have radiation after mastectomy.

Those with a greater than 15 percent risk of chest wall (local) recurrence over 10 years tended to be diagnosed younger than 40 and:

  • have cancer in more than four lymph nodes, or
  • have less than eight uninvolved lymph nodes (those without cancer) removed

Women with a greater than 10 percent chance of recurrence in the lymph nodes above the collar bone over 10 years often had more than 11 positive lymph nodes. 

Those with a more than 5 percent chance of recurrence in the lymph nodes in the armpit over 10 years were often:

  • diagnosed younger than 40
  • had less than eight uninvolved lymph nodes removed

For women with three or fewer positive lymph nodes, certain traits predicted a more than 10 percent chance of chest wall recurrence over 10 years, including:

  • being diagnosed younger than 40
  • having less than eight negative lymph nodes removed
  • showing signs of vascular invasion, or cancer cells entering blood vessels where they can travel to the lymph nodes or other areas of the body

Based on these data, the investigators recommend that radiation to the chest wall and lymph nodes above the collar bone should be used after mastectomy in women younger than 40 who have four or more positive lymph nodes with less than 8 uninvolved lymph nodes removed. For women with one to three positive lymph nodes, they suggest radiation should be considered if the woman is younger than 40, and has seven or fewer negative lymph nodes or vascular invasion.

What This Means For You

The use of radiation after mastectomy continues to be the focus of discussion in the medical community. These findings suggest ways for your doctors to determine whether you should have radiation after mastectomy, and to help you avoid radiation treatment when it is not necessary. 

As you make a treatment plan with your healthcare team, talk with your doctors about their recommendations for radiation therapy and these findings. For a list of questions to consider, download or order a copy of our Guide to Understanding Treatment Decisions.

Karlsson, P., Cole, B.F., et al: Patterns and risk factors for locoregional failures after mastectomy for breast cancer: an International Breast Cancer Study Group report. Ann Oncol (2012) 23 (11): 2852-58.

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