Estimating long-term mortality in women with hormone receptor-positive breast cancer: The 'ESTIMATE' tool

The risk of breast cancer-specific mortality (BCSM) persists for at least 20 years from diagnosis. Estimating the risk of BCSM over this extended period along with competing risks of death would aid clinical decision-making. We aimed to develop an interactive tool called 'ESTIMATE', to explore the Surveillance, Epidemiology, and End Results (SEER) registry to quantify residual risks of BCSM, non-BCSM and all-cause mortality in non-metastatic, hormone receptor (HR)-positive breast cancer patient subgroups at any given time after diagnosis, up to 20 years.

Using SEER data, we included 264,237 women with invasive, non-metastatic, HR-positive breast cancer diagnosed from 1990 to 2006. We developed a tool that provides a nonparametric estimate of the residual cumulative risk of BCSM and non-BCSM by year 20 after any specified time from initial diagnosis, among patients defined by baseline clinical and pathologic variables, using Gray's subdistribution method.

ESTIMATE allows the user to input patient and tumour characteristics and the preferred timeframe. For example, patients in the age group of 40-49 diagnosed with T1cN1, grade II breast cancer who survived 7 years, have a 14% (95% confidence interval [CI]: 11.9%-16.1%) residual cumulative risk of BCSM in the next 13 years, and a 6.4% (95% CI: 4.7%-8.1%) residual cumulative risk of non-BCSM over the same period.

ESTIMATE provides population-based risks of BCSM, non-BCSM and all-cause mortality through 20 years after diagnosis of HR-positive breast cancer, based on patient and tumour characteristics. ESTIMATE can inform discussions about prognosis, a balance between competing risks and aid clinical decision-making.