Breast Cancer Mortality Rates Decreased Over Time in Population-Based Analysis

Researchers identified improvements in 5-year mortality risks over time in a study of more than 500,000 women with a history of early invasive breast cancer. Study results were recently reported in the journal BMJ.

“Our study provides, for the first time, estimates of prognosis based on all patients recently receiving a diagnosis of breast cancer in the whole of England,” the researchers wrote in their report.

The study was an observational cohort study based on data from the National Cancer Registration and Analysis Service in England. It included women for whom breast cancer was considered their first invasive cancer, with registration occurring from January 1993 to December 2015. Information related to mortality among these women was followed until December 31, 2020.

The researchers estimated annual breast cancer mortality rates and cumulative risks by time since diagnosis. In addition to other analyses, the researchers calculated mortality-related outcomes by calendar period of diagnosis, with periods ranging from 1993 through 1999, 2000 through 2004, 2005 through 2009, and 2010 through 2015.

The majority (60%) of the 512,447 women in the analysis had undergone breast-conserving surgery, while 40% underwent mastectomy. Numbers of women receiving a diagnosis of early breast cancer rose over the years of the study period.

The age range of women for whom breast cancer screening was offered also increased over the years. In women eligible for screening, approximately half the detected cancers had been found through screening.

For all calendar periods of diagnosis, annual breast cancer mortality rates increased during the initial 2 years after diagnosis and was highest in the third year, before falling. However, across the calendar periods, the cumulative breast cancer mortality risks fell over time.

For women whose diagnosis was in the period of 1993 through 1999, the crude 5-year breast cancer mortality risk was 14.4% (95% CI, 14.2%-14.6%). This risk reduced progressively over time to 4.9% (95% CI, 4.8%-5.0%) for those whose diagnosis was during 2010 through 2015.

Adjusted annual breast cancer mortality rates also declined, to varying degrees, over calendar periods across multiple patient groups.

“Our findings illustrate the substantial improvement in prognosis for women with a diagnosis of early invasive breast cancer that has been made since the 1990s,” the researchers wrote in their report.

“Finally, our findings can be used to reassure most women treated for early breast cancer that they are likely to become long term survivors.”

Reference

Taylor C, McGale P, Probert J, et al. Breast cancer mortality in 500 000 women with early invasive breast cancer in England, 1993-2015: population based observational cohort study. BMJ. 2023;381:e074684. doi:10.1136/bmj-2022-074684