Benefits of radiotherapy after breast-conserving surgery

January 01, 0001

Benefits of radiotherapy after breast-conserving surgery

After breast-conserving surgery, radiotherapy reduces recurrence and breast cancer death, but it may do so more for some groups of women than for others. The international group of researchers describe the absolute magnitude of these reductions according to various prognostic and other patient characteristics, and relate the absolute reduction in 15-year risk of breast cancer death to the absolute reduction in 10-year recurrence risk. They undertook a meta-analysis of individual patient data for 10,801 women in 17 randomised trials of radiotherapy versus no radiotherapy after breast-conserving surgery, 8337 of whom had pathologically confirmed node-negative (pN0) or node- positive (pN+) disease.

Overall, radiotherapy reduced the 10-year risk of any (ie, locoregional or distant) first recurrence from 35.0% to 19.3% and reduced the 15-year risk of breast cancer death from 25.2% to 21.4%. In women with pN0 disease (n=7287), radiotherapy reduced these risks from 31.0% to 15.6% and from 20.5% to 17.2%, respectively. In these women with pN0 disease, the absolute recurrence reduction varied according to age, grade, oestrogen-receptor status, tamoxifen use, and extent of surgery, and these characteristics were used to predict large (greater than or equal to 20%), intermediate (10—19%), or lower (<10%) absolute reductions in the 10-year recurrence risk. Absolute reductions in 15-year risk of breast cancer death in these three prediction categories were 7.8%, 1.1% and 0.1% respectively. In the few women with pN+ disease (n=1050), radiotherapy reduced the 10-year recurrence risk from 63.7% to 42.5% and the 15-year risk of breast cancer death from 51.3% to 42.8%. Overall, about one breast cancer death was avoided by year 15 for every four recurrences avoided by year 10, and the mortality reduction did not differ significantly from this overall relationship in any of the three prediction categories for pN0 disease or for pN+ disease.

The researchers concluded: "After breast-conserving surgery, radiotherapy to the conserved breast halves the rate at which the disease recurs and reduces the breast cancer death rate by about a sixth. These proportional benefits vary little between different groups of women. By contrast, the absolute benefits from radiotherapy vary substantially according to the characteristics of the patient and they can be predicted at the time when treatment decisions need to be made."

Targeted therapy is an interesting area, but it may be difficult to make the call (although not the GP’s role).

For the full abstract, click here.

The Lancet published online 20 October 2011 © 2011 to Elsevier Ltd.
Effect of radiotherapy after breast- conserving surgery on 10-year recurrence and 15-year breast cancer death: meta-analysis of individual patient data for 10,801 women in 17 randomised trials. Early Breast Cancer Trialists' Collaborative Group (EBCTCG).

Category: X. Female Genital System, Breast. Keywords: breast cancer, surgery, radiotherapy, recurrence, death, meta-analysis of randomised trials, journal watch.
Synopsis edited by Dr Stephen Wilkinson, Melbourne, Australia. Posted on Global Family Doctor 18 November 2011

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