Evaluation of exercise tolerance in women receiving surgery and chemotherapy as treatment for stage II breast cancer

Worldwide, breast cancer is the second-most-common cause of cancer deaths in women (Harvey and Beattie, 1996). It is estimated that by the year 2000, one million women a year will receive a diagnosis of breast cancer, while in Canada alone, the disease develops in 18,400 women every year (National Cancer Institute of Canada, 1997). The development and improvement of new treatment modalities for breast cancer have resulted in increasing cure rates and longer disease-free survival making the outcome of cancer therapy increasingly important. Damaging effects of cancer therapies can occur in the heart and lungs and therefore are thought to impede the patient's functional capacity and ability to exercise. The purpose of this study was to characterize the early changes in functional capacity that occur in women diagnosed with stage II breast cancer, whose treatment involves a schedule of mastectomy and adjuvant chemotherapy. Nine female patients performed the treatment protocol at three different sessions: 1) after diagnosis of breast cancer but before surgery, 2) following surgery but before beginning chemotherapy, and 3) following chemotherapy. Testing sessions involved two protocols and the subjects served as their own controls throughout the three tests. Firstly, resting pulmonary function was assessed using the Spirometry software package on the Medical Graphics CPX-D Metabolic Cart. Forced Vital Capacity (FVC), forced expiratory volume in one second (FEV1), the ratio of the two (FEV1/FVC), and maximal voluntary ventilation (MVV) were measured. The second protocol was a V0₂max test on an electronically-braked cycle ergometer (Lode BV Excalibur V2.0) using a Medical Graphics CPX-D Exercise Testing System. Measurements included maximal heart rate (HRmax), minute ventilation (VE), maximal oxygen consumption (V02max), and peak power output (PPO). While cycling, percent arterial oxygen saturation (%Sa02) was monitored with a pulse oximeter (Ohmeda Box 3740). Anthropometric measures including height, weight and sum of skinfolds (SOS) were recorded before each test. Data was analyzed using a one-way repeated measures A N O V A design on SPSS and subsequent Tukey HSD post-hoc analyses were performed by hand. A probability value of < 0.05 was considered to provide significance. V 0 2 m a x values, measured both in L/min and ml/kg/min decreased significantly from baseline to the end of chemotherapy (1.70 ± 0.31 to 1.47 ± 0.31 L/min; and 28.3 ± 5.54 to 24.52 ± 6 . 1 3 ml/kg/min, respectively). FEV1/FVC and M V V did not change significantly throughout the treatment. PPO, HRm a x , Sa02 , and V E also remained unchanged after chemotherapy treatment. Although respiratory function was not affected, the data suggests that breast cancer patients treated with chemotherapy experience a decrease in cardiorespiratory fitness and associated loss of functional capacity.

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