Bridging the Age Gap in Breast Cancer, a large, prospective, multicenter cohort study of older women (>70 years) in the UK, was conducted to evaluate treatment patterns and survival outcomes in those with primary breast cancer (BC) with or without coexisting cognitive impairment (CI) or dementia.

To be eligible for inclusion in the study, which took place between February 2013 and June 2018, participants had to have a new diagnosis of primary operable BC and be >70 years old. Those with metastatic disease or previous invasive BC within 5 years were excluded.

Cognitive status was based on proxy status (i.e., used to define severe CI) as well as the Mini-Mental State Examination or the Charlson Index,(a method for classifying comorbid conditions that might alter the risk of mortality for use in longitudinal studies).

A total of 3,416 women were enrolled, including 2,938 (86%) who were cognitively intact and 478 (14%) with CI or dementia. Of these 478 women, 336 (9.8%) had mild, 59 (1.7%) had moderate, and 83 (2.4%) had severe CI. The median age of the study population based on cognitive status for normal cognition, mild CI, moderate CI, and severe CI was 76, 79, 80, and 83 years, respectively.

Investigators found that although there were no differences in nodal status, tumor grade, or hormonal/HER2 receptor status between the groups, women with moderate-to-severe CI had larger tumors at presentation.

Primary treatment information, which was available for almost all women (97%), showed that 82.3% underwent surgery with or without adjuvant treatment and 14.8% were treated only with primary endocrine therapy (PET; e.g., aromatase inhibitors).

Cognitive status was associated with BC surgery (with or without adjuvant therapy), with patients with normal cognition more likely to have surgery compared with those with mild, moderate, or severe CI: 84.9%, 73.8%, 61.0%, and 39.8%, respectively (P <.001).

Both PET treatment and no treatment were more common as CI increased. PET treatment was prescribed for 12.4% of patients with normal cognitive function, 22.3% of those with mild CI, 35.6% of those with moderate CI, and 51.8% of those with severe CI (P <.001). No treatment or unknown treatment occurred in 2.7% of women with normal cognitive function, 3.9% of those with mild CI, 3.4% of those with moderate CI, and 8.4% of those with severe CI (P <.001). A similar trend of increased use of PET in women with CI was seen among those with estrogen receptor–positive disease.

There were no statistically significant differences based on cognitive status for the use of adjuvant chemotherapy following surgery, for the use of radiotherapy in women following surgery or in those with a high-risk histology post mastectomy, and for those with HER2+ disease who received trastuzumab.  

Patients with CI had over two times the risk of dying than those without CI (hazard ratio for reduced overall survival: 2.1, P <.001). However, this effect size was greatly reduced when other patient factors (e.g., age, treatment, Nottingham Prognostic Index) were considered. CI was linked to higher rates of overall mortality but had limited impact on BC-related deaths, as BC-specific survival and progression-free survival rates were similar between groups.

This study provides pharmacists with valuable insight into the treatment strategies used among older women with BC. It also highlights an opportunity for pharmacists to have a proactive role in assessing adherence and monitoring for adverse events associated with PET in older women with varying degrees of CI.

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