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26-02-2021 | Breast cancer | News

Risk tool predicts chemotherapy toxicity in older breast cancer patients

Author: Hannah Kitt

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medwireNews: US researchers have developed the Cancer and Aging Research Group–Breast Cancer (CARG–BC) score to help predict grade 3–5 chemotherapy-related toxicities in older patients with early-stage breast cancer.

“These findings may be useful to clinicians for predicting individual probability of chemotherapy toxicity and directing therapy in older adults with early-stage breast cancer,” say Allison Magnuson (University of Rochester, New York) and team.

“Intensifying supportive care and developing modified treatment regimens may be appropriate for subgroups identified as being vulnerable to greater toxicity,” they add.

The researchers stress, however, that “this score should not be used as the only factor in deciding whether to administer and/or alter the dose or schedule of chemotherapy,” but believe that it “can be used to facilitate this complex decision-making process, along with clinical judgment and patient preferences.”

All 473 patients in the study were aged 65 years or older (median 70 years), had stage I–III breast cancer, and were scheduled to receive neoadjuvant or adjuvant chemotherapy at one of 16 US institutions. In all, 27.7% had HER2-positive disease and 23.7% had triple-negative disease.

Using data from the 283 patients who comprised the development cohort, the investigators identified the following eight clinical and geriatric factors that independently predicted grade 3–5 chemotherapy toxicity, and assigned them weighted points to form the CARG–BC score:

  • Planned treatment duration greater than 3 months (4 points); 
  • Falls in past 6 months (4 points);
  • Stage II–III disease (3 points); 
  • Abnormal liver function (3 points);
  • Low hemoglobin (≤12 g/dL in women, ≤13 g/dL in men; 3 points);
  • Limited ability to walk (3 points); 
  • Lack of social support (3 points); and
  • Planned use of anthracyclines (1 point).

As described in the Journal of Clinical Oncology, the median score for patients in the development group was 7 points, and each 1-point increase was associated with a significant 28% increased risk for grade 3–5 toxicities. The CARG–BC model showed “good discrimination,” say the authors, identifying individuals likely to experience such toxicity with an accuracy of 75%.

When patients were stratified into low-, intermediate-, and high-risk groups based on scores of 0–5, 6–11, and 12–24 points, respectively, the rates of grade 3–5 toxicities were 19%, 54%, and 87%, respectively. And patients in the intermediate- and high-risk groups were a significant 4.91 and 28.13 times more likely to develop toxicity than those in the low-risk group.

The model was validated in a cohort of 190 patients, among whom the rates of grade 3 or worse toxicity were 27%, 45%, and 76%, in the low-, intermediate-, and high-risk groups, respectively, while the accuracy of the model was 69%.

And further analysis showed the CARG–BC to “outperform” the existing tools used to predict grade 3–5 chemotherapy toxicities, namely the general CARG toxicity tool and the physician-rated Karnofsky performance status, in this older patient population, say the researchers.

Of note, the CARG–BC score “was also strongly associated with dose reductions, dose delays, reduced dose intensity, and hospitalizations,” highlight Magnuson and colleagues.

“These findings may be useful to clinicians for predicting individual probability of chemotherapy toxicity and directing therapy, to researchers for designing and interpreting clinical trials, and to policymakers for allocating future resources for new strategies to mitigate the risk of chemotherapy toxicity,” they write.

The researchers caution, however, that “although the CARG-BC was validated in a separate cohort of patients, these patients were accrued from the same institutions as the development cohort.”

They add: “While this is an established method for validation, further validation in a more diverse population should be considered in the future.”

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2021 Springer Healthcare Ltd, part of the Springer Nature Group

J Clin Oncol 2021; doi:10.1200/JCO.20.02063

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