Effects of Cytotoxic Chemotherapy and Endocrine Therapy on Hemodynamics and Oxygen Uptake During Handgrip Exercise in Patients Treated for Breast Cancer

Breast cancer therapies can alter skeletal muscle blood flow during exercise and decrease mitochondrial content and function. However, the impact of different therapies on the variables determining oxygen transport and utilization during submaximal exercise remain unknown. We tested the hypothesis that both chemotherapy and endocrine therapy would decrease blood flow and increase deoxygenated [hemoglobin+myoglobin] (HHb) with an unchanged oxygen uptake (VȮ2) during exercise compared to healthy controls. Participants were healthy females (CTRL; n = 5; age: 58 ± 8 years; body mass index: 25 ± 4 kg/m2) or female patients diagnosed with stage I-III breast cancer comprising three groups: 1) two to five weeks post completion of cytotoxic chemotherapy (CHEMO; n = 5; age: 55 ± 8 years; body mass index, BMI: 30 ± 4 kg/m2); 2) currently on endocrine therapy ≥5 months (ENDO; n = 9; age: 59 ± 7 years; BMI: 27 ± 6 kg/m2); and 3) completed cytotoxic chemotherapy and currently on endocrine therapy ≥5 months (CHEMO+ENDO; n = 8; age: 58 ± 6 years; BMI: 26 ± 5 kg/m2). Forearm blood flow, HHb, and estimated VȮ2 were measured during the final minute of a 3-minute intermittent isometric handgrip exercise at 3 and 6 kg. There were no group or group x intensity effects (all p<0.18) for forearm blood flow (CTRL: 260 ± 33 ml/min; CHEMO: 407 ± 96 ml/min; ENDO: 309 ± 140 ml/min; CHEMO+ENDO: 313 ± 86 ml/min), HHb (CTRL: 134 ± 58 μM; CHEMO: 73 ± 36 μM; ENDO: 118 ± 67 μM; CHEMO+ENDO: 101 ± 25 μM), or estimated VȮ2 (CTRL: 59 ± 28 ml/min; CHEMO: 48 ± 21 ml/min; ENDO: 54 ± 28 ml/min; CHEMO+ENDO: 53 ± 21 ml/min). These findings indicate that chemotherapy and endocrine therapy do not affect muscle hemodynamics and oxidative metabolism during submaximal handgrip exercise. This study was funded, in part, by the Veterans Affairs Clinical Science Research and Career Development Award (IK2 CX002114). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.