A new prediction score for grade 3-5 chemotherapy toxicity in patients with breast cancer was developed during a multicenter, prospective cohort study. The findings were published in the Journal of Clinical Oncology.

Existing tools for predicting the risk of chemotherapy toxicity in patients older than 65 with early-stage breast cancer are not reliable because they were developed and validated using younger patients, and heterogeneous populations with various cancer subtypes, stages, and chemotherapy regimens. Therefore, a team of researchers sought to develop a tool that is specific to disease and treatment variables relevant to older patients with early-stage breast cancer.

A total of 501 patients with breast cancer aged 70.5±4.4 years were recruited from 16 centers in the United States between 2011 and 2017. Potential risk factors were assessed prior to adjuvant or neoadjuvant chemotherapy and patients were assessed for toxicity or adverse events. The Cancer and Aging Research Group-Breast Cancer (CARG-BC) score was developed and validated using final cohorts of 283 and 190 patients, respectively. Seventeen patients in the development cohort and 11 in the validation cohort were excluded because they were treated with nonstandard regimens.

Patients had stage I (36.2%), II (42.9%), or III (20.9%) cancer, 27.7% had HER2-positive disease and 23.7% had triple-negative disease. Nearly half (48.7%) developed grade 3-5 chemotherapy toxicity (hematologic: 26.9%; nonhematologic: 38.5%).


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The CARG-BC score comprises 8 predictors: cancer stage (II or III), anthracycline-based regimen, more than 3 months of chemotherapy, abnormal liver function, presence of anemia, limited mobility, 1 or more falls during the previous 6 months, and having a poor support network.

No predictors had significant interactions and the adjusted area under the receiving operator characteristic curve (AUC) was 0.73 for predicting toxicity.

Scores ranged from 0 to 24 (low: 0 to 5; intermediate: 6 to 11; and high: 12 or higher). Every 1-point increase in CARG-BC score was associated with elevated risk for toxicity (odds ratio [OR], 1.28; 95% CI, 1.19-1.38; P <.001).

These results may not be generalizable because of bias in the study population (99.4% women, 72.7% college educated).

The validated risk score effectively stratified older patients at risk for chemotherapy toxicity by incorporating treatment details with geriatric assessment.

Reference

Magnuson A, Sedrak MS, Gross CP, et al. Development and validation of a risk tool for predicting severe toxicity in older adults receiving chemotherapy for early-stage breast cancer. J Clin Oncol. Published online January 14, 2021. doi:10.1200/JCO.20.02063