Adjuvant Radiotherapy Use Questioned for Low-Risk Breast Cancer in Older Women

Adjuvant radiation offers relatively small benefit for older women undergoing breast-conserving surgery and endocrine treatment for low-risk disease

medwireNews: PRIME II study findings challenge the need for radiotherapy in women aged 65 years or older with low-risk breast cancer who undergo breast-conserving surgery and adjuvant endocrine therapy.

“[F]or women aged 65 years or older with early hormone Receptor-positive node-negative breast cancer (≤3 cm at the longest dimension) after breast-conserving surgery, adjuvant endocrine treatment alone is a reasonable therapeutic option for some women”, Ian Kunkler, from the University of Edinburgh in the UK, and co-authors write in The Lancet Oncology.

However, they caution: “We must stress that every patient should be assessed individually, with tumour characteristics, comorbidity, and patient's choice as determining factors, along with an assessment of benefits and risks of treatment.”

The results of the PRIME II study show that the 658 patients who were randomly assigned to receive 40 to 50 Gy whole-breast radiotherapy in addition to breast-conserving surgery and endocrine therapy had a significantly lower 5-year risk of ipsilateral breast cancer recurrence than the 668 patients who received surgery and endocrine therapy alone (1.3 vs 4.1%), giving a number needed to treat of 31.8.

But adjuvant radiotherapy did not significantly alter the risk of regional recurrence or distant metastases, nor the likelihood of new breast cancers or contralateral breast cancer developing in the patients.

And the 5-year overall survival rate was 93.9% in both treatment groups, with breast cancer-related deaths reported for just four of the 40 deceased patients who received adjuvant radiotherapy and eight of the 49 deceased patients given only surgery and endocrine treatment.

Writing in an accompanying comment, Kevin Hughes, from Massachusetts General Hospital in Boston, USA, and Lauren Schnaper, from Greater Baltimore Medical Center in Maryland, USA, discuss the PRIME II authors’ recommendation to consider omitting postoperative radiotherapy for some patients.

“We not only wholeheartedly agree, but would go a step further to suggest that not only should omission of radiotherapy be considered, it should actually be omitted in all women who meet the eligibility requirements of this trial”, they say.

The commentators conclude: “PRIME II adds to the growing body of knowledge that radiation has minimal real benefit for women aged 65 years and older with Oestrogen receptor-positive tumours of 3 cm or smaller.

“It is time to stop radiating these older women.”

References

Kunkler IH, Williams LJ, Jack WJL, et al. Breast-conserving surgery with or without irradiation in women aged 65 years or older with early breast cancer (PRIME II): a randomised controlled trial. Lancet Oncol 2015; Online First 27 January. DOI: dx.doi.org/10.1016/S1470-2045(14)71221-5

Hughes KS, Schnaper LA. Can older women with early breast cancer avoid radiation? Lancet Oncol 2015; Online First 27 January. DOI: dx.doi.org/10.1016/S1470-2045(15)70014-8

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