Radiation to Regional Lymph Nodes Reduces Recurrence but Doesn’t Improve Survival

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After surgery to remove early-stage breast cancer, many women will have radiation therapy to the breast area. Radiation is given to reduce the risk of the cancer coming back in the breast area and nearby tissue (loco-regional recurrence).

Doctors sometimes also recommend that lymph nodes near the area where the breast cancer was removed be included in the area that gets radiation. This is called regional lymph node radiation. Regional lymph node radiation may include the internal mammary lymph nodes, which are the nodes underneath the chest wall, the medial supraclavicular lymph nodes, which are the lymph nodes above the collar bone near the center of the body, and the axillary lymph nodes, which are the lymph nodes under the arm. Regional lymph node radiation usually is recommended only for certain women diagnosed with breast cancer that has already spread to one or more nearby lymph nodes and/or who are considered to have a higher-than-average risk of the breast cancer coming back in the same area.

Two studies suggest that regional lymph node radiation after surgery to remove early-stage breast cancer reduces the risk of the cancer coming back (recurrence) but doesn’t improve overall survival. Overall survival is how long women live, with or without the cancer coming back.

The studies were published in the July 23, 2015 issue of The New England Journal of Medicine. Read the abstracts of:

The first study was done by Canadian researchers and included 1,832 women diagnosed with early-stage breast cancer that was either node-positive or node-negative with a high risk of recurrence. The women all had lumpectomy. The researchers randomly assigned the women to one of two radiation treatment groups:

  • 916 women were treated with whole-breast radiation plus regional node radiation that included internal mammary, supraclavicular, and axillary lymph nodes (called the nodal radiation group)
  • 916 women were treated with whole-breast radiation alone (called the control group)

The characteristics of the cancers and treatments after surgery in each group were similar:

  • about 8.9% of the cancers were node negative, about 50% had one positive node, about 25% had two positive nodes, about 11% had three positive nodes, and about 5% had more than 3 positive nodes
  • about 75% of the cancers were estrogen-receptor-positive
  • about 90% of the women had chemotherapy after surgery
  • about 75% of the women took hormonal therapy after surgery

After about 10 years of follow-up, the researchers found there was no difference in overall survival between the nodal radiation group and the control group: about 82% of the women in each group were alive.

There was a difference in disease-free survival rates -- how long the women lived without the cancer coming back:

  • 82% of the women in the nodal radiation group were alive with no recurrence
  • 77% of the women in the control group were alive with no recurrence

This difference was statistically significant, which means that it was likely due to the difference in treatment and not just because of chance.

Still, women in the nodal radiation group were more likely to have side effects:

  • 8.4% of the women in the nodal radiation group had lymphedema compared to 4.5% of women in the control group
  • 1.2% of the women in the nodal radiation group had acute pneumonitis, a severe lung disease that involves coughing up a lot of thick mucus, compared to 0.2% of women in the control group

The second study was done by European researchers and involved 4,004 women from 13 countries. All the women were diagnosed with early-stage breast cancer and had had lumpectomy or mastectomy. The researchers randomly assigned the women to one of two treatment groups:

  • 2,002 women were treated with whole-breast radiation plus regional node radiation that included internal mammary and supraclavicular lymph nodes (the nodal radiation group)
  • 2,002 women were treated with whole-breast radiation alone (the control group)

As in the Canadian study, the characteristics of the cancers and the treatments after surgery in each group were similar:

  • about 10% of the cancers were node-negative, about 49% had one positive node, about 23% had two positive nodes, about 11% had three positive nodes, and about 5% had more than three positive nodes
  • about 75% of the cancers were estrogen-receptor-positive
  • about 76% of the women had lumpectomy, the rest had mastectomy
  • about 90% of the women had chemotherapy after surgery
  • about 25% of the women took hormonal therapy after surgery

After about 10 years of follow-up, the European researchers found the same results as the Canadian researchers: there was no difference in overall survival between the nodal radiation group and the control group -- about 81% of the women in each group were alive.

Again, there was a difference in disease-free survival:

  • 72.1% of the women in the nodal radiation group were alive without the cancer coming back
  • 69.1% of the women in the control group were alive without the cancer coming back

This difference was statistically significant.

The European researchers also looked at rates of distant disease-free survival -- how long the women lived without the cancer coming back in a part of the body away from the breast. Again, nodal radiation made a difference:

  • 78% of the women in the nodal radiation group were alive with no distant recurrence
  • 75% of the women in the control group were alive with no distant recurrence

This difference also was statistically significant.

When the researchers looked at just women with positive lymph nodes and women with cancers that were located closer to the breast bone or more in the center of the breast, they found that radiation to the regional lymph nodes reduced the risk that these women would die from breast cancer.

As in the Canadian study, the women in the nodal radiation group were more likely to have side effects:

  • 8.4% of the women in the nodal radiation group had lymphedema compared to 4.5% of women in the control group
  • 49.5% of women in the nodal radiation group had skin irritation compared to 40.1% of women in the control group

The European researchers said that the results of their study didn’t apply to women diagnosed with cancers that were node-negative and in the area of the breast nearer to the arm pit, which is where most breast cancers are located.

When deciding on breast cancer treatments, you and your doctor will talk about your unique situation and carefully weigh the benefits against any risks. Expanding the radiation treatment area to include the internal mammary and the medial supraclavicular lymph nodes might be recommended if the cancer is node-positive and located near the breast bone.

“We now have better treatments to give after surgery, such as chemotherapy, targeted therapies, and hormonal therapy, which may decrease the need for radiation to the lymph nodes,” said Breastcancer.org Chief Medical Officer Dr. Marisa Weiss, M.D., breast radiation oncologist, Lankenau Medical Center, part of Main Line Health, a five-hospital health system in the suburbs of Philadelphia, PA. “But at the same time, sentinel lymph node surgery allows us to remove fewer lymph nodes in women with positive nodes, which may increase the need for radiation to the remaining lymph nodes.

“For the best care now, there is more than one right way to go,” she continued. “Radiation oncologists around the world will differ in their recommendations. Generally, for women with four or more positive lymph nodes, radiation to the supraclavicular lymph nodes often is recommended. And, if the cancer is in the central to inner area of the breast, then radiation also may be recommended to the internal mammary lymph nodes. For women who have one to three positive nodes, the role of radiation is more likely to fall into a grey zone.”

Dr. Weiss also explained that whether or not radiation is recommended may depend on how much cancer is in each lymph node and if there is “extracapsular extension” -- cancer that spills just outside the involved lymph node.

If you've been diagnosed with early-stage breast cancer, it's a good idea to ask your doctor if the cancer has spread to the lymph nodes and the treatment options recommended because of that spread. You may want to ask about your risk of the cancer coming back and if radiation therapy is recommended for you, as well as whether nodal radiation makes sense for your unique situation.

Although these studies suggest that nodal radiation shouldn't be done routinely, it still may make sense for you based on the specifics of your situation. This may be especially true if the cancer is located near the breast bone or if your risk of the cancer coming back in the same area is much higher than average.

Visit the Breastcancer.org Radiation Therapy section to learn more about the role of radiation therapy in breast cancer treatment, the ways it may be given, and what to expect during treatment.



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