Age and Comorbidity Affect Completion of Adjuvant Trastuzumab Therapy in Older Patients With Early-Stage Breast Cancer
In a population-based study reported in the Journal of Clinical Oncology, Vaz-Luis et al assessed duration and toxicity of adjuvant trastuzumab (Herceptin) in older patients with early-stage breast cancer. They found that age and comorbidity affected treatment completion rates and that significant cardiac events were more common in those not completing therapy, suggesting that cardiac toxicity is a significant factor in failure to complete therapy in such patients.
Study Details
The study included Surveillance, Epidemiology, and End Results (SEER)-Medicare data on 2,028 women aged ≥ 66 years with stage I to III breast cancer diagnosed between 2005 and 2009 who received trastuzumab. Most patients were aged < 76 years (71%), had a comorbidity score of 0 (67%), were white (82%), and had received trastuzumab with chemotherapy (85%); chemotherapy was anthracycline- and taxane–based in 25%, taxane-based in 41%, single-agent taxane in 10%, anthracycline-based in 6%, and other in 3%. Overall, 82% of patients completed trastuzumab treatment (received > 270 days of therapy).
Age and Comorbidity
In multivariate analysis adjusting for all demographic and clinical characteristics, older patients (odds ratio [OR] = 0.57 for age 76–80 years and 0.40 for >80 years vs 66–70 years; P < .001) and those with higher Charlson comorbidity scores (OR = 0.82 for 1 and 0.65 for ≥ 2; P = .03) were significantly less likely to complete trastuzumab therapy. Completion of trastuzumab was significantly more likely in patients receiving anthracycline-based treatment (OR = 1.57) and those receiving taxane-based treatment (OR = 1.98) compared with those receiving anthracycline- and taxane-based therapy (P < .001) and was borderline more likely in patients receiving lumpectomy vs mastectomy (OR = 1.24, P = .05).
Cardiac Events
During treatment through 30 days after the last trastuzumab claim, 73 patients (3.6%) had 84 hospital admissions for cardiac events, including 2.6% of those who completed trastuzumab vs 8.1% of those who did not (P < .001). Patients who completed treatment were significantly less likely to have a cardiac event requiring admission during treatment (OR = 0.32, 95% confidence interval = 0.21–0.49).
Among women hospitalized for cardiac events, median time to admission was significantly shorter in those who did not complete treatment (65 days vs 217 days, P < .001). Patients who had a history of cardiac disease (9.6% vs 2.7%, P < .001) and those with prior heart failure (10.3% vs 3.4%, P = .002) had a higher likelihood of requiring cardiac admission during treatment than those without.
Overall, 56% of the cardiac admissions were followed by another trastuzumab claim, including 25% of the cardiac admissions for patients who did not complete trastuzumab therapy. During the year after the last adjuvant trastuzumab claim, 4.0% of patients had 101 hospital admissions for cardiac events, including 2.3% of those who completed trastuzumab therapy vs 11.6% of those who did not (P < .001). Heart failure/cardiomyopathy admission was significantly more likely in patients who did not complete trastuzumab therapy (6.7% vs 1.5%, P < .001). The rate of hospital admission during the year after stopping trastuzumab was higher in women with prior hospitalizations (50.7% vs 2.3%, P < .001).
The investigators concluded, “Most older patients who initiated adjuvant trastuzumab completed therapy. Age and comorbidity were among factors that were associated with treatment completion, and rates of significant cardiac events were higher in those who did not complete therapy. Further exploration of toxicities and optimal treatments for older women with human epidermal growth factor receptor 2-positive breast cancer are warranted.”
Rachel A. Freedman, MD, MPH, of the Dana-Farber Cancer Institute, is the corresponding author for the Journal of Clinical Oncology article.
For full disclosures of the study authors, visit jco.ascopubs.org.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
