Breast-Conserving Surgery Plus Radiotherapy ‘At Least Equivalent’ To Mastectomy

Dutch population-based study findings may influence treatment decision-making in early breast cancer

medwireNews: Overall and relative survival results from the Netherlands Cancer Registry add support for the use of breast-conserving surgery plus radiotherapy in women with early-stage breast cancer.

And with a specific subgroup of women also deriving a distant metastasis-free survival benefit, the researchers believe that “breast-conserving surgery plus radiotherapy is at least equivalent to mastectomy with respect to long-term survival in early breast cancer”.

They add in The Lancet Oncology: “Although the choice of mastectomy is increasing, primarily due to fear of recurrent cancer, use of [magnetic resonance imaging], and access to immediate reconstruction, our study might influence this choice by reducing patients’ fears of recurrent cancer after breast-conserving surgery plus radiotherapy.”

Commentator Beryl McCormick, from Memorial Sloan Kettering Cancer Center in New York, USA, thinks that “[t]he evidence is emphatic; those of us responsible for the treatment of women with early-stage breast cancer should communicate this message clearly to our patients.”

Among 37,207 patients diagnosed with stage T1–2, N0–1, nonmetastatic breast cancer between 2000 and 2004, 10-year overall survival was significantly longer for the 21,734 who underwent breast-conserving surgery plus radiotherapy than for the 15,473 who had a mastectomy, with an adjusted hazard ratio (HR) of 0.81.

“[T]his improvement remained significant for all subgroups of different T and N stages of breast cancer”, comment researcher Sabine Siesling, from Netherlands Comprehensive Cancer Organisation in Utrecht, and co-workers.

They also evaluated breast cancer-specific survival, as estimated by distant metastasis-free and relative survival, in a representative subcohort of women diagnosed during 2003, of whom 4647 received breast-conserving surgery while 2905 underwent mastectomy.

Breast-conserving surgery versus mastectomy was associated with a significant improvement in 10-year relative survival (adjusted excess mortality ratio=0.76), but not 10-year distant metastasis-free survival in the overall 2003 cohort.

However, in the subgroup of women with T1N0 disease, both 10-year relative and distant metastasis-free survival were longer with breast-conserving surgery, with an adjusted excess mortality ratio of 0.60 and an adjusted HR of 0.74, respectively.

In her commentary, Beryl McCormick observes: “The results confirm older randomised trials, and more recent registry-based studies, and the statistical methodology and inclusion of all women should address many of the concerns with both registry studies and applicability of randomised data to the general population.”

But she wonders whether this study will “finally be viewed by all specialties in the medical community as conclusive evidence that breast conservation surgery plus radiotherapy provides women with stage 1 breast cancer a better outcome than mastectomy, provided the patient is not a carrier of mutations in BRCA? Or will the myth persist?”

The commentator emphasizes: “A myth supporting an aggressive surgical procedure that is less effective for breast cancer cure than is breast conservation surgery plus radiotherapy should be recognised as an untrue and harmful belief.”

References

van Maaren MC, de Munck L, de Bock GH, et al. 10 year survival after breast-conserving surgery plus radiotherapy compared with mastectomy in early breast cancer in the Netherlands: a population-based study. Lancet Oncol 2016; Advance online publication 22 June. doi: http://dx.doi.org/10.1016/S1470-2045(16)30067-5

McCormick B. The mastectomy myth.Lancet Oncol 2016; Advance online publication 22 June. doi: http://dx.doi.org/10.1016/S1470-2045(16)30219-4

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