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CARG-BC score

Predicts risk of severe chemotherapy toxicity (grade 3-5) in patients aged over 65 with early stage breast cancer
Breast cancer stage
II or III 3 points
I 0 points
Planned use of anthracyclines
Yes 1 points
No 0 points
Planned treatment duration
>3 months 1 points
≤3 months 0 points
Haemoglobin
≤12 g/L (female) 3 points
≤13 g/L (male) 3 points
>12 g/L (female) 0 points
>13 g/L (male) 0 points
Liver function tests
Abnormal LFTs, outside reference range 3 points
Normal LFTs, within reference range 0 points
Number of falls in last 6 months
≥1 4 points
0 0 points
Does patient's health limit them walking more than 1 mile?
Yes 3 points
No 0 points
How often is someone available to give patient advice about a crisis
None, little, or some of the time 3 points
Most or all of the time 0 points
CARG-BC score:

CARG-BC score: Predicting chemotherapy toxicity risk in older adults with early breast cancer

Interpretation
Predicting toxicity risk to chemotherapy in older adults is challenging due to the heterogeneous nature of this population. The CARG-BC tool was developed to predict risk of severe (grade 3-5) chemotherapy toxicity in patients aged over 65 with early stage breast cancer (1).

The tool originates from the previously published CARG tool which looked at toxicity in multiple cancer subtypes, stages and treatment regimens. The CARG-BC tool has been specifically developed for patients with early-stage breast cancer and aims to provide more accurate risk estimation.

The score was developed using a population of 473 patients (283 in the development and 190 in the validation cohorts). Patients were aged ≥65 years, with stage I-III breast cancer and had received neoadjuvant or adjuvant chemotherapy. 8 independent predictor variables were identified and the risk of G3-5 chemotherapy toxicity was divided into one of 3 categories as detailed in the table below.

Risk category CARG-BC Score G3-5 toxicity risk (%)
Low 0-527
Medium 6-11 45
High >12 76

The model performance measured by receiver operator characteristic area under the curve (ROC-AUC) analysis, was 0.69 (95% CI, 0.62 to 0.77) in the validation cohort. The tool was found to outperform the original CARG tool and also Karnofsky performance status in patients with early stage breast cancer.

References:
  1. 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 Off J Am Soc Clin Oncol. 2021;39(6):608-618. doi:10.1200/JCO.20.02063