Tumor blood flow at rest and during exercise in breast cancer patients
INTRODUCTION: It has been suggested and studied that cancer patients would exercise during their chemotherapy drug infusions. The reasoning for that is that pre-clinical studies have shown tumor blood flow (BF) to increase during exercise, which would enhance drug delivery into the tumor. However, this remains sparsely investigated in the clinical setting in cancer patients and was therefore the topic of the present investigation, also because basic physiological responses to physical exercise in the tumor are largely unknown in patients.
AIMS AND OBJECTIVES: The main aim of the present study was to elucidate tumor BF during exercise.
METHODS: Tumor BF was quantified in twenty breast cancer patients with [15O]-H2O positron emission tomography imaging at rest and during supine cycling in the scanner (individually chosen intensity by Borg scale, RPE 11-16). BF was also measured in non-cancerous, contralateral breast tissue. Paired t-test was used for statistical comparisons. The study was approved by the Ethical committee of Hospital District of South-West Finland and patients gave their written informed consent before their participation.
RESULTS: Tumor BF was at rest 12,7±8,5 ml/(dl/min) and during exercise 8,7±8,1 ml/(dl/min), p=0.004. Thus, tumor BF was significantly reduced from rest to during exercise condition. BF in the contralateral healthy breast tissue was much lower and was not significantly changed from rest to exercise (2,0±1,9 ml/(dl/min at rest and 1,6±1,7 ml/(dl/min) during exercise, p=ns).
CONCLUSIONS: To the best of our knowledge this is the first study to investigate tumor blood flow during exercise in breast cancer patients. We report that tumor blood flow is reduced during exercise from the resting baseline in these patients. These results do not support the reasoning that at least breast cancer patients should exercise during their chemotherapy infusions, but whether the responses differ between different cancer patient groups/tumors remains to be investigated. It also remains to be investigated whether tumor blood flow is returned back to baseline after exercise.