Abstract
The purpose of this study is to determine how receipt of guideline-concordant care (GCC) is associated with breast cancer-specific mortality (BCSM) and non-breast cancer mortality (NBCM) among older women with breast cancer. The SEER-Medicare data was used to identify 142, 433 women age > 66 diagnosed with stage I-III breast cancer between 2007-2011. Receipt of GCC was determined according to evidence-based treatment guidelines. Cause-specific Cox proportional hazard multivariable regression models were used to estimate the association between GCC and the risk of BCSM, considering NBCM as a competing event, and NBCM, considering BCSM as a competing event, within five years of diagnosis or until end of follow-up. Among older women with breast cancer, 6.5% experienced BCSM and 11.9% experienced NBCM. GCC was associated with a 24% decreased risk of BCSM (AHR, 0.76; 95% CI, 0.71-0.82), but a 80% increased risk of NBCM (AHR, 1.80; 95% CI, 1.70-1.92). Receipt of adjuvant endocrine therapy was associated with an increased risk of BCSM and a decreased risk for NBCM. Receipt of chemotherapy was associated with an increased risk for BCSM and NBCM, while radiation therapy was associated with a decreased risk of NBCM. Women with a pre-existing dementia, arthritis, hypertension, stroke and increased comorbidity burden had an increased risk for BCSM. Most older breast cancer patients do not receive GCC, yet relatively few die from breast cancer. While GCC does decrease the risk of BCSM, the decision to treat should be made considering the patients existing health status, given that pre-existing comorbidity increases the risk for both BCSM and NBCM. Mortality differences associated with specific types of treatment may be attributed to patient selection for treatment based on worse cancer prognostic factors.
Highlights
The majority of older women diagnosed with breast cancer have less aggressive subtypes, [1, 2] older women experience worse breast cancer-specific mortality (BCSM) at every stage and sub-type, compared to younger women. [3] Older women with breast cancer are at greater risk of non-breast cancer mortality (NBCM), especially those with greater comorbidity. [4] The concurrent increased risk for BCSM and NBCM may present challenges to the treatment decision making process for many older patients
It is well documented that older breast cancer patients are often undertreated, as compared to their younger counterparts. [6, 7] a recent study reported that only 40% of women age > 66 years received treatment according to evidence-based guidelines, or guidelineconcordant care (GCC), [8] possibly contributing to the
Primary reasons associated with lower rates of GCC include older age, greater comorbidity, treatment toxicity, decreased functional status and limited life-expectancy. [9,10,11] epidemiological studies have reported conflicting findings as to whether or not receipt of GCC and specific treatments are associated with improved BCSM and/or NBCM among older women. [12,13,14] An important, but previously unconsidered factor is the concept of competing risks of death
Summary
The majority of older women diagnosed with breast cancer have less aggressive subtypes, [1, 2] older women experience worse breast cancer-specific mortality (BCSM) at every stage and sub-type, compared to younger women. [3] Older women with breast cancer are at greater risk of non-breast cancer mortality (NBCM), especially those with greater comorbidity. [4] The concurrent increased risk for BCSM and NBCM may present challenges to the treatment decision making process for many older patients. [3] Older women with breast cancer are at greater risk of non-breast cancer mortality (NBCM), especially those with greater comorbidity. [9,10,11] epidemiological studies have reported conflicting findings as to whether or not receipt of GCC and specific treatments are associated with improved BCSM and/or NBCM among older women. [12,13,14] An important, but previously unconsidered factor is the concept of competing risks of death Competing events, such as NBCM, are important to account for when estimating cause-specific endpoints such as BCSM, [15] especially given that over 70% of deaths among women age > 75 years with breast cancer, are due to non-breast cancer causes. Competing events, such as NBCM, are important to account for when estimating cause-specific endpoints such as BCSM, [15] especially given that over 70% of deaths among women age > 75 years with breast cancer, are due to non-breast cancer causes. [16] the purpose of the current study is to investigate how GCC is associated with the risk of BCSM, considering NBCM as a competing event, and the risk of NBCM, considering BCSM as a competing event, among a large US population-based cohort of older women with breast cancer
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