Abstract 273P
Background
Muscle loss has been identified as a negative prognostic factor in various types of cancer, including breast cancer. In particular, muscle loss is a significant prognostic factor in patients with metastatic cancer. While chemotherapy is a crucial treatment for breast cancer that can improve survival rates, it also has significant side effects, such as severe infections due to reduced white blood cells, bone marrow failure, fluid retention, and heart toxicity. However, muscle loss as a result of chemotherapy in breast cancer patients has not been widely recognized. Recent studies on cancer treatment and prognosis have highlighted muscle loss as an important concern, and this study aims to determine the extent of muscle loss in breast cancer patients after undergoing chemotherapy.
Methods
This retrospective study analyzed patients who underwent surgery for early breast cancer between 2015 and 2019. Demographic data and clinicopathological features were analyzed, and the lumbar skeletal muscle index (psoas muscle) in computed tomography (CT) was used as a marker of muscle mass. Muscle index was compared in abdominal CT taken before surgery and abdominal CT taken 1 year later.
Results
Of the 408 patients included in the study, 228 received adjuvant chemotherapy, and 180 patients did not receive adjuvant chemotherapy. The muscle index of patients who did not receive chemotherapy decreased by 0.4cm2/m2, while that of patients who received chemotherapy decreased by 1.2cm2/m2 (p = 0.028). In multivariate analysis, chemotherapy and age over 50 were identified as the main risk factors for muscle mass reduction (p = 0.02, 0.03, respectively). Table: 273P
Clinicopathologic features of 408 patients
| Variables | Chemotherapy Pts (N=228) | Non-chemotherapy Pts (N = 180) | P values |
| Age | 54.8 ± 10.4 (28-67) | 56.1 ± 9.6 (30-69) | 0.445 |
| Stage | 0.001 | ||
| I | 40 (17.5 %) | 116 (64.4%) | |
| II | 160 (70.2%) | 61 (33.9%) | |
| III | 28 (12.3%) | 3 (1.7%) | |
| Hormone receptor | |||
| Positive | 155 (68%) | 158 (88%) | 0.001 |
| Negative | 73 (32%) | 22 (12%) | |
| HER2 receptor | |||
| Positive | 70 (31%) | 20 (11%) | 0.048 |
| Negative | 158 (69%) | 160 (86%) | |
| BMI | 24.7 | 24.1 | 0.78 |
| Muscle mass index (MI) | 46.6 cm2/m2 | 46.9 cm2/m2 | 0.66 |
| MI reduction | -1.2 cm2/m2 | -0.4 cm2/m2 | 0.028 |
Conclusions
This study demonstrates that significant muscle loss occurs in patients who receive chemotherapy after surgery for early breast cancer. In particular, patients aged 50 or older who have received chemotherapy need to pay attention to muscle reduction.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.