Comorbidities Can Be as Important as Stage in Predicting Breast Cancer Survival in Older Patients

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Comorbidities can be as important as stage in predicting survival among older women with breast cancer, according to a study in the Journal of the National Cancer Institute. While previous studies have combined comorbidities into a summary measure or comorbidity index, the current study assessed the individual associations between 13 selected comorbidities and overall survival among patients with breast cancer aged 66 or older, using the Surveillance, Epidemiology, and End Results–Medicare database.

“Each of the 13 comorbid conditions examined was associated with decreased overall survival and increased mortality,” the authors reported. Comorbidities with the highest fully adjusted hazard ratios were liver disease (HR of death = 2.32), chronic renal failure (HR of death = 2.20), dementia (HR of death = 1.96), and congestive heart failure (HR of death = 1.70). Other comorbidities studied were previous cancer, myocardial infarction, peripheral vascular disease, cerebrovascular disease, chronic obstructive pulmonary disease, paralysis, diabetes, stomach ulcer, and rheumatoid arthritis. Among the 60,034 patients identified, 37,306 (58%) had none of these comorbid conditions, 28% had one, 8.8% had two, and 4.9% had three or more. Overall survival was estimated using age-specific Kaplan-Meier curves.

Key Findings

“Across all of the comorbid conditions, patients aged 66 to 74 years with stage I tumors who had these conditions had survival curves similar to patients with stage II tumors who had no comorbidities. Similar trends were observed in the Kaplan-Meier survival curves for patients aged 75 to 84 years and 85 years or older.” the authors stated.

The most common survival pattern (seen in association with myocardial infarction, peripheral vascular disease, stroke, chronic obstructive pulmonary disease, and diabetes) for patients with earlier-stage cancers and comorbidities was to have survival outcomes shifted about one stage higher compared with patients without comorbidities. “For more severe comorbidities (eg, dementia, chronic renal failure, and liver disease), the survival outcomes of patients with stage I and stage II tumors who had the specific comorbid condition resembled that of patients with stage III and IV tumors who did not have the specific conditions,” the investigators noted.

Patnaik JL, et al: J Natl Cancer Inst 103:1101-1111, 2011.