Cancer is hard on the body. As it develops, affecting various systems, the entire body may have to work harder to operate, resulting in a much faster heart rate. Fevers can cause elevated heart rates, as can dehydration and thyroid issues.
The cancer may also be contributing to tiredness and fatigue, meaning even simple actions may get the heart pumping faster than usual. Some experts even believe that these heart rate changes could predict mortality in cancer cases.

This site offers information designed for educational purposes only. You should not rely on any information on this site as a substitute for professional medical advice, diagnosis, treatment, or as a substitute for, professional counseling care, advice, diagnosis, or treatment. If you have any concerns or questions about your health, you should always consult with a physician or other healthcare professional.