Research table: Radiation therapy after a mastectomy for invasive breast cancer treatment

This summary table contains detailed information about research studies. Summary tables are a useful way to look at the science behind many breast cancer guidelines and recommendations. However, to get the most out of the tables, it’s important to understand some key concepts. Learn how to read a research table.

Introduction: Radiation therapy isn’t often given after a mastectomy for women with early-stage breast cancer. However, there are some cases when it’s recommended, and some cases when it should be considered.

When is radiation therapy after a mastectomy for early breast cancer recommended?

The National Comprehensive Cancer Network (NCCN) recommends radiation therapy after a mastectomy for early breast cancer for women with 4 or more positive lymph nodes to improve overall survival [1].

A meta-analysis combined the results of 22 randomized clinical trials on radiation therapy after a mastectomy. Among women with 4 or more positive lymph nodes, it found radiation therapy lowered the risk of [2]:

• Breast cancer recurrence (a return of breast cancer)
• Death from breast cancer

When should radiation therapy after a mastectomy for early breast cancer be considered?

The NCCN recommends radiation therapy after a mastectomy be strongly considered for women who have [1]:

• 1-3 positive lymph nodes
• Positive tumor margins (when surgery to get negative tumor margins can’t be done)

The NCCN recommends radiation therapy after a mastectomy be considered for women with negative lymph nodes who have [1]:

• A tumor larger than 5 centimeters
• A tumor 5 centimeters or smaller, but the tumor margins are close

Learn more about radiation therapy.

Learn about the short-term side effects and the long-term health risks of radiation therapy.

Learn more about lymph node status, tumor margins and tumor size.

Learn about guidelines for the treatment of early breast cancer.

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	Study Population (number of participants)	Stage of Breast Cancer*	Number of Positive Nodes	Overall Survival (for length of follow-up)
				Radiation Therapy after a Mastectomy	No Radiation Therapy after a Mastectomy
Randomized clinical trials
DBCG 82b Trial [3]	3,083	Stage II-III	1-3	Overall survival at 15 years: 49% Overall survival at 30 years: 22%	Overall survival at 15 years: 40%SIG Overall survival at 30 years: 19%SIG
			4 or more	Overall survival at 15 years: 22% Overall survival at 30 years: 11%	Overall survival at 15 years: 12%SIG Overall survival at 30 years: 3%SIG
SUPREMO Trial [4]	1,607	Stage I-III	0-3	Overall survival at 10 years: 81%	Overall survival at 10 years: 82%NS,†
Meta-analyses
EBCTC [2]	3,131	Stage II-III	1 or more	Overall survival at 20 years: 35%	Overall survival at 20 years: 30%SIG
	1,314	Stage II-III	1-3	Overall survival at 20 years: 46%	Overall survival at 20 years: 43%NS
	1,772	Stage II-III	4 or more	Overall survival at 20 years: 25%	Overall survival at 20 years: 17%SIG
Gebski et al. [5]	6,946‡	Stages I-III	1 or more	Overall survival at 10 years: 53%	Overall survival at 10 years: 47%SIG,§

SIG = Statistically significant difference between groups

NS = No statistically significant difference between groups

* Breast cancer stage as classified before 2018

† There was also no difference in overall survival at 10 years between women who had lymph node-negative breast cancer and those with lymph node-positive breast cancer.

‡ Only included studies that used optimal radiation dose and coverage

§ Calculated from data in study

References

1. National Comprehensive Cancer Network. NCCN Clinical practice guidelines in oncology: Breast cancer, Version 5.2025. http://www.nccn.org, 2025.
2. 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.
3. Overgaard M, Nielsen HM, Tramm T, et al. for the DBCG Radiotherapy Group. Postmastectomy radiotherapy in high-risk breast cancer patients given adjuvant systemic therapy. A 30-year long-term report from the Danish breast cancer cooperative group DBCG 82bc trial. Radiother Oncol. 170:4-13, 2022.
4. Kunkler IH, Russell NS, Anderson N, et al. for the SUPREMO Trial Investigators and Sunil. Ten-year survival after postmastectomy chest-wall irradiation in breast cancer. N Engl J Med. 393(18):1771-1783, 2025.
5. 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.

Updated 11/19/25