This summary table contains detailed information about research studies. Summary tables offer an informative look at the science behind many breast cancer guidelines and recommendations. However, they should be viewed with some caution. In order to read and interpret research tables successfully, it is important to understand some key concepts. Learn how to read a research table.
Introduction: Radiation therapy is not often used after mastectomy for women with stage I or II breast cancer. However, it is recommended for women with four or more positive lymph nodes to improve survival . Radiation therapy should also be considered for women with :
The results of two large randomized clinical trials with more than 10 years of follow-up suggest women with lymph node-positive (stage II or III) breast cancer benefit from radiation therapy after mastectomy [2-3].
A meta-analysis that combined the results of 22 randomized clinical trials found that for women with lymph node-positive breast cancer, radiation therapy after mastectomy lowered the risk of recurrence and the risk of dying from breast cancer . This study also showed that radiation therapy improved overall survival in women with four or more positive lymph nodes .
Older studies of radiation therapy show an increase in deaths from breast cancer in the opposite breast, heart disease and lung cancer . Modern radiation therapy is given in lower doses than in the past and thus, these health risks appear to be much lower . For example, studies of modern radiation therapy after breast surgery show no increased risk of breast cancer in the opposite breast [6-8].
Learn about the strengths and weaknesses of different types of studies.
Study selection criteria: Randomized clinical trials with at least 1,000 participants and 10 or more years of follow-up and meta-analyses.
Study Population(number of participants)
Stage ofBreast Cancer
Number ofPositive Nodes
Radiation Therapy afterMastectomy
No Radiation Therapy afterMastectomy
Randomized clinical trials
DBCG 82b Trial 
1,708 premenopausal women
Stage II & III
4 or more
DBCG 82c Trial 
1,375 postmenopausal women
1 or more
Gebski et al. 
SIG = Statistically significant difference between groups
NS = No statistically significant difference between groups
* Only included studies that used optimal radiation dosage and coverage
† Calculated from data in study
1. National Comprehensive Cancer Network. NCCN Clinical practice guidelines in oncology: Breast cancer, version 3.2013. http://www.nccn.org, 2013.
2. Overgaard M, Hansen PS, Overgaard J, et al. Postoperative radiotherapy in high-risk premenopausal women with breast cancer who receive adjuvant chemotherapy. Danish Breast Cancer Cooperative Group 82b Trial. N Engl J Med. 337:949-55, 1997.
3. Overgaard M, Jensen MB, Overgaard J, et al. Postoperative radiotherapy in high-risk postmenopausal breast cancer patients given adjuvant tamoxifen: Danish Breast Cancer Cooperative Group DBCG 82c randomised trial. Lancet. 353:1641-8, 1999.
4. McGale P, Taylor C, Correa C, et al. for the Early Breast Cancer Trialists' Collaborative Group (EBCTCG). Effect of radiotherapy after mastectomy and axillary surgery on 10-year recurrence and 20-year breast cancer mortality: meta-analysis of individual patient data for 8135 women in 22 randomised trials. Lancet. 383(9935):2127-35, 2014.
5. Early Breast Cancer Trialists' Collaborative Group. Favourable and unfavourable effects on long-term survival of radiotherapy for early breast cancer: an overview of the randomised trials. Lancet. 355:1757-70, 2000.
6. Neilson HM, Overgaard M, Grau C, et al. Study of failure pattern among high-risk breast cancer patients with or without postmastectomy radiotherapy in addition to adjuvant systemic therapy: long-term results from the Danish Breast Cancer Cooperative Group DBCG 82 b and c randomized studies. J Clin Oncol. 24(15):2268-75, 2006.
7. Kirova YM, Gambotti L, De Rycke Y, Vilcoq JR, Asselain B, Fourquet A. Risk of second malignancies after adjuvant radiotherapy for breast cancer: a large-scale, single-institution review. Int J Radiat Oncol Biol Phys. 68(2):359-63, 2007.
8. Berrington de Gonzalez A, Curtis RE, Gilbert E, et al. Second solid cancers after radiotherapy for breast cancer in SEER cancer registries. Br J Cancer. 102(1):220-6, 2010.
9. Gebski V, Lagleva M, Keech A, et al. Survival effects of postmastectomy adjuvant radiation therapy using biologically equivalent doses: a clinical perspective. J Natl Cancer Inst. 98(1):26-38, 2006.
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