Begin Screening In 40s to Reduce Breast Cancer Mortality

Screening mammography beginning around the age of 40 years may reduce breast cancer-specific mortality

medwireNews: Long-term results from the UK Age trial support the use of breast cancer screening for women in their 40s, demonstrating a significant reduction in mortality for the first 10 years of screening with a minimal risk of overdiagnosis.

“Although the UK Age trial arose to address concerns related to the interpretation of incomplete data, it confirmed the fact that screening women in their 40s saves lives”, writes Daniel Kopans, from Harvard Medical School in Boston, Massachusetts, USA, in a comment accompanying the article in The Lancet Oncology.

“Had both screening views been used, and had clustered calcifications been biopsied, the UK Age trial would have probably shown a much larger decrease in deaths in the intervention group,” he suggests.

By contrast, “[n]o scientific evidence exists for a screening threshold at the age of 50 years, and women and their physicians should not be misled”, the commentator adds.

The UK Age trial randomly assigned women aged 39 to 41 years to begin annual mammography until their 48th birthday (n=53,883) or to receive usual care (n=106,953), with an invitation to begin screening at age 50 years and at 3-year intervals thereafter, report Sue Moss, from the Wolfson Institute at Queen Mary University of London in the UK, and co-authors.

After a median of 17 years, the rate ratio (RR) for breast cancer mortality from tumours detected during intervention was 0.88 in favour of early breast screening.

Moreover, breast cancer mortality was significantly lower for the first 10 years in women who underwent screening in their 40s than those who received usual care (RR=0.75), although this reduction was no longer significant after this time.

Based on an average screening uptake of 65%, this gave a number needed to invite of 2108 and a number needed to screen of 1366 to avoid one death from breast cancer diagnosed during the intervention phase.

The researchers note that the overall incidence of breast cancer during follow-up, including patients diagnosed after entry to the study, was comparable between the early screening and usual care patients, with an RR of 0.98.

“Thus, our results provide no evidence that screening in the trial resulted in any overdiagnosis in addition to any occurring as a result of [National Health Service Breast Screening Programme] screening, which cannot be assessed because of lead time”, Moss et al emphasise.

The authors explain that the introduction of two-view mammography in the screening programme since the UK Age trial was initiated has improved detection of small breast cancers and reduced both recall rates and the incidence of interval tumours.

“[I]f the UK Age trial were done now, the intervention might have a greater effect because of the improved detection of ductal carcinoma in situ and small invasive tumours”, they conclude.

References

Moss SM, Wale C, Smith R, et al. Effect of mammographic screening from age 40 years on breast cancer mortality in the UK Age trial at 17 years’ follow-up: a randomised controlled trial. Lancet Oncol 2015; Advance online publication 21 July. http://dx.doi.org/10.1016/S1470-2045(15)00128-X

Kopans DB. The UK Age trial: screening women in their forties. Lancet Oncol 2015; Advance online publication 21 July. http://dx.doi.org/10.1016/S1470-2045(15)00057-1

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