Earlier Breast Cancer Screening Reduces Risk of Death

For women in their 40s, starting annual mammography screening for breast cancer offers a 25-percent reduction in the risk of death at 10 years of follow-up, new research has revealed.

In a study published Aug. 12 in Lancet Oncology, researchers from Queen Mary University of London Center for Cancer Prevention outlined the impact of earlier screening. The team did note, though, that the benefits associated with earlier screening dissipated at subsequent follow-ups.

“The benefit is seen mostly in the first 10 years, but the reduction in mortality persists in the long term at about one life saved per thousand women screened,” said lead study author Stephen Duffy, professor of cancer screening, in a press statement.

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Currently, the U.K. National Health Service (NHS) begins offering breast cancer screening to women every three years when they reach age 50. But, Duffy’s team wanted to determine the effect and long-term outcomes of initiating screening at ages 40 or 41.

To make this determination, they launched the U.K. Breast Screening Age Trial and enrolled nearly 161,000 women between October 1990 and September 1997. All women were between the ages of 39 and 41. Investigators divided the women into two groups – one that received annual mammography beginning at ages 40 or 41 and one that followed the existing NHS screening program. They follow the groups for 23 years.

According to the team’s analysis, at the 10-year follow-up point, women who received annual screening prior to age 50 experienced a 25-percent lower relative risk of death from breast cancer. The difference was statistically significant at this first follow-up, but it was no longer present at subsequent follow-ups, the team said.

Given these outcomes, Duffy’s team determined their early screening efforts resulted in 11.5 years of life saved per 1,000 women screened – a total of 620 life years for the study group as a whole.

Alongside the analysis of the impact on years of life saved, the team also evaluated the loss of mortality benefit over time. They postulated that the drop off was linked to a diminished effect the earlier screening had on grade 3 tumors, noting that in some cases, the cancers were postponed rather than prevented. In addition, they pointed to earlier generation technologies, such as film-screen mammography with single views, that could impact the quality of images.

“We now screen more thoroughly and with better equipment than in the 1990s when most of the screening in this trial took place,” Duffy said, “so the benefits may be greater than we’ve seen in this study.”

Overall, the team said, the results support the use of annual breast cancer screening at an earlier age to save patient lives. And, further research efforts could uncover whether more up-to-date technologies and treatments could augment outcomes for the younger patient population even more.