Breast cancer deaths highest within 5 years from diagnosis, decrease afterwards

The risk of mortality for women with early invasive breast cancer is highest during the 5 years after diagnosis, according to a study. Deaths from breast cancer will continue beyond this point, but such risk tends to decrease during each subsequent 5-year period.

“For these reasons, we presented the 5-year breast cancer mortality risks for women with a diagnosis made during 2010‒2015 with different combinations of age, screening status, oestrogen receptor status, number of positive nodes, and tumour size and grade,” the researchers said. “Clinicians can use this information to estimate breast cancer mortality risks for patients today.”

Routinely collected data from the National Cancer Registration and Analysis Service were used in this population-based observational cohort study. A total of 512,447 women registered with early invasive breast cancer (involving only breast and possibly axillary nodes) in England from January 1993 to December 2015, with follow-up to December 2020, were included in the analysis.

Among women who had had a diagnosis within each of the calendar periods 1993‒1999, 2000‒2004, 2005‒2009, and 2010‒2015, the crude annual breast cancer mortality rate was highest during the first 5 years following diagnosis and then declined thereafter. [BMJ 2023;381:e074684]

Crude annual breast cancer mortality rates and risks decreased with increasing calendar period for any given time since diagnosis. Crude 5-year breast cancer mortality risks were 14.4 percent (95 percent confidence interval [CI], 14.2‒14.6) for women who were diagnosed during 1993‒1999 and 4.9 percent (95 percent CI, 4.8‒5.0) for those diagnosed during 2010‒2015.

Likewise, the adjusted annual breast cancer mortality rates declined with increasing calendar period in almost every patient cohort, by a factor of about three in oestrogen receptor positive disease and about two in oestrogen receptor negative disease.

When only patients diagnosed during 2010‒2015 were considered, the cumulative 5-year breast cancer mortality risks were markedly different between women with diverse characteristics: <3 percent for 62.8 percent (96,085/153,006) of women but ≥20 percent for 4.6 percent (6,962/ 153,006) of women.

Implications

“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 said. “More than six in 10 of the women given the diagnosis in England during 2010‒2015 had a risk of dying from breast cancer during the following 5 years of 3 percent or less, and nearly nine in 10 had a risk below 10 percent.”

These findings have several implications. First, these mortality risks can inform patients about their prognosis. Second, low event rates may make it difficult to achieve adequate power in randomized trials. Third, decreases in breast cancer deaths can affect decision aids used in the clinic to estimate the absolute benefits of adjuvant treatments for patients.

“Finally, our findings can be used to reassure most women treated for early breast cancer that they are likely to become long-term survivors,” the researchers said. “They can also be used to identify the groups of women for whom the risk of breast cancer mortality remains substantial.”