Abstract P1-08-11: The impact of existing comorbidities on survival disparities among women diagnosed with invasive breast cancer
Authors: Connor AE , May B , Schmaltz CL , Jackson-Thompson J , Visvanathan K 
Published: May 2019

Missouri is one of many states in the US burdened by high rates of mortality from female breast cancer (BC) as well as comorbidities such as Type-2 diabetes, cardiovascular disease (CVD), and hypertension. These comorbidity rates are higher among vulnerable populations including individuals in poverty and/or living in rural areas, African Americans, and the elderly. There is evidence that women with comorbidities at the time of BC diagnosis have a worse prognosis. We hypothesize that the co-existence of comorbidities is likely to impact survival and may contribute to survival disparities observed among women diagnosed with BC from these vulnerable populations.

Objective: To examine whether the number and/or type of comorbidity at BC diagnosis is associated with higher BC and all-cause mortality among women diagnosed with invasive BC in Missouri between 2004 and 2012.

Methods: Women age 18+ diagnosed with BC in Missouri during 2004–2012 were identified from the Missouri Cancer Registry. These data were then merged with hospital discharge data from the Missouri Patient Abstract System. Associations were evaluated in all women and by race, neighborhood poverty level, rural/urban residence, and age at diagnosis. A comorbidity score was constructed to account for the number of comorbidities (Type-2 diabetes, hypertension, and CVD) identified for each individual. Hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox proportional hazards regression models, adjusting for age at diagnosis, race, tumor hormone receptor status, stage, BC treatment, and rural/urban residence. Models were further stratified by race, poverty level, rural/urban residence, and age group.

Results: A total of 31,133 women with incident invasive BC and with comorbidity data at the time of BC diagnosis were included in the analysis. After a median follow-up time of 79 months, 9,912 deaths occurred, of which 4,900 deaths were due to BC. Increasing number of comorbidities was significantly associated with BC mortality (ptrend &lt; 0.001). BC mortality (HR, 1.33; 95% CI 1.19-1.49) and all-cause mortality (HR, 1.51; 90% CI 1.32-1.61) were significantly higher in women with ≥2 comorbidities. CVD accounted for the largest increase in BC mortality (HR, 1.36; 95% CI 1.19-1.55). In stratified analyses, we did not observe significant differences in associations by race, poverty, rural/urban residence, or age; however, there was a statistically significant interaction with age when modeled as a continuous measure, comorbidity score, and risk of mortality outcomes (p&lt; 0.001). White women with all 3 comorbidities had the highest risk of death (BC-specific: HR, 1.95; all-cause: HR, 2.28). Women in rural areas with ≥2 comorbidities were 1.78 times more likely to die of BC while women living in the metro with all 3 comorbidities were almost 2 times more likely to die of any cause.

Conclusion: Our results demonstrate the negative impact that comorbidities such as diabetes, CVD, and hypertension can have on BC and overall mortality in a diverse group of BC patients diagnosed and treated in Missouri. The data produced from this study can be utilized to identify and implement targeted preventive strategies to improve the quality of life and survival of BC patients.

Citation Format: Connor AE, May B, Schmaltz CL, Jackson-Thompson J, Visvanathan K. The impact of existing comorbidities on survival disparities among women diagnosed with invasive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-08-11.