Evaluation of early subclinical cardiotoxicity of chemotherapy in breast cancer.

Objective: Cardiac effects of chemotherapy are usually recognized after clinical symptom or sign occurrence in patients with breast cancer. In this study, we aimed to determine the potential subclinical cardiotoxic effects of chemotherapy that were given lower dosage than well known cardiac safety dosage limits in patients with breast cancer during early period.

Methods: Fifty-one patients consecutively enrolled to this prospective cohort study. All patients were diagnosed as breast cancer at oncology hospital in University of Gaziantep. Before chemotherapy, all of the patients underwent to detailed ECG and echocardiography (ECHO) examinations. After 6 months, detailed ECG and ECHO examinations were repeated and compared with baseline values. Statistical analysis was performed using Shapiro-Wilk tests, Student t-test and Spearman correlation test.

Results: The average age of patients was 51 and one was male. Statistically significant decrease in ejection fraction was found after treatment (62.3%±3.3 and 59.9%±5.9, p=0.002). Evaluation of diastolic parameters; significant increase in the transmitral A flow velocity and significant decrease of E/A ratio were observed on Doppler ECHO analysis (77.4±19.1 cm/sec versus 86±18 cm/sec, p<0.001; 1.01±0.3 versus 0.9±0.2, p=0.03, respectively). On tissue Doppler analysis we observed that significant reduction in the value of E' and significantly increase E/E' ratio were present (12.5±3.6 cm/sec versus 10.7±2.9 cm/sec, p=0.001; 6.6±2.9 versus 7.7±3.3, p=0.04, respectively).

Conclusion: Chemotherapy has detrimental subclinical effect on both of systolic and diastolic function in early six months period despite the prescription of lower dosage of chemotherapy than well-known cardiac safety dosage limits. Tissue Doppler imaging may be more sensitive than ECG, conventional ECHO and Doppler for determining the subclinical cardiac damage.