Decreased breast cancer recurrence and mortality following post-mastectomy radiotherapy

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1. Radiotherapy administered after mastectomy and axillary dissection decreased 10-year recurrence and 20-year mortality in women with node-positive breast cancer. 

2. No reduction in recurrence and mortality was shown for women with node-negative breast cancer who were given radiotherapy following mastectomy and axillary dissection. 

Evidence Rating Level: 1 (Excellent) 

Study Rundown: Radiotherapy has been used in clinical practice to treat any remaining tumor foci following mastectomy and axillary dissection in women with node positive breast cancer. Current guidelines recommend adjuvant radiotherapy after mastectomy for women with four or more positive axillary lymph nodes. However, no previous analysis has clearly shown the utility of radiotherapy for women with one to three positive nodes. This meta-analysis suggests a benefit of radiotherapy in this population, as evidenced by decreased rates of recurrence and breast cancer mortality in women with one to three positive lymph nodes. A limitation of this study is how far in the past the women were treated. Patients who received radiotherapy between the years of 1964 to 1980 were included. Advances made in the effectiveness of more non-invasive treatments, particularly, targeted systemic therapies, likely renders patients today at a lower overall risk for recurrence and mortality. As a result, it becomes difficult to generalize these results for today’s population.

Click to read the study in Lancet

Relevant Reading:Effects of radiotherapy and of differences in the extent of surgery for early breast cancer on local recurrence and 15-year survival: an overview of the randomised trials

In-Depth [meta-analysis]: Over 8000 women from 22 randomized clinical trials of adjuvant radiotherapy versus no radiotherapy following mastectomy  with axillary dissection were included in the analysis. For women with no positive nodes after axillary dissection, there was no change in rates of local recurrence, overall recurrence, or breast cancer mortality. Radiotherapy did reduce the local recurrence (p<.00001), overall recurrence (RR = 0.68, 95% CI 0.57-0.82, p<.0001) and breast cancer mortality (RR = 0.80, 95% CI 0.67-0.95, p=.01) in women with one to three positive nodes. 86% of these women were concurrently on systemic therapy, and significant reductions in all three parameters were maintained with radiotherapy. Reductions in local recurrence (p<.00001), overall recurrence (RR = 0.79, 95% CI 0.69-0.90, p<.001), and breast cancer mortality (RR = 0.87, 95% CI 0.77-0.99, p<.05) were also found in women shown to have four or more positive lymph nodes.

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