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Postmastectomy radiotherapy reduced recurrence, mortality
Radiotherapy following mastectomy and axillary dissection reduced long-term breast cancer recurrence and mortality among women with one to three positive lymph nodes, according to results of a meta-analysis.
Prior research from the Early Breast Cancer Trialists’ Collaborative Group at the Clinical Trial Service Unit in Oxford, United Kingdom, showed radiotherapy following mastectomy reduced mortality in women with four or more positive lymph nodes.
In current study, Paul McGale, a senior statistician in the collaborative group, and colleagues evaluated data on 3,786 women who participated in 14 randomized trials that began between 1964 and 1982.
Paul McGale
All women had axillary dissection to at least level II, and they had zero, one to three, or four or more positive nodes. All study participants underwent radiotherapy to the chest wall, supraclavicular and/or axillary fossa, and internal mammary chain.
Among 700 women with zero positive nodes, radiotherapy demonstrated no significant effect on locoregional recurrence, overall recurrence (rate ratio [RR]=1.06; 95% CI, 0.76-1.48) or breast cancer mortality (RR=1.18; 95% CI, 0.89-1.55).
Among 1,314 women with one to three positive nodes, radiotherapy reduced locoregional recurrence (P<0.00001), overall recurrence (RR=0.68; 95% CI, 0.57-0.82) and breast cancer mortality (RR=0.80; 95% CI, 0.67-0.95). The majority of women (86.2%) with one to three positive nodes were enrolled in trials in which systemic therapy (cyclophosphamide, methotrexate and fluorouracil, or tamoxifen) was administered. Among those women, radiotherapy reduced locoregional recurrence (P<0.00001), overall recurrence (RR=0.67; 95% CI, 0.55-0.82) and breast cancer mortality (RR=0.78; 95% CI, 0.64-0.94).
Among the 1,772 women with four or more positive nodes, radiotherapy reduced locoregional recurrence (P<0.00001), overall recurrence (RR=0.79; 95% CI, 0.69-0.9) and breast cancer mortality (RR=0.87; 95% CI, 0.77-0.99).
“Since the time when the women in these trials were randomized, there have been advances in radiotherapy and also in breast screening, surgery, lymph node staging and systemic therapy,” McGale said in a press release. “The absolute benefits from postmastectomy radiotherapy today may be smaller than those we have reported here, but the proportional benefits from radiotherapy are likely to be at least as big.”
Disclosure: The researchers report funding from Cancer Research UK, the British Heart Foundation and the UK Medical Research Council.