Exercise has been part of my life for as long as I can remember. I was a competitive gymnast and ski racer as a kid and picked up running as a late teen to stay in shape. Exercise is like brushing teeth for me. If I don't do it, I don't feel right. Because of this, I knew that I needed to ensure that I could continue to stay active while going through my breast cancer treatment.
I think that the words cancer or chemotherapy typically bring up images of extreme sickness and debilitation for most people. I have taken care of enough patients through chemotherapy to know that this can be true. Most of my patients who had been working prior to their diagnosis, went on disability while on chemotherapy and had a significant shift in their normal activities. And I will also admit, that although I knew that staying active was a good idea in general for my patients and I gave generic advice to get outside and get some fresh air and go for a walk if possible, I did not spend significant time during their clinic visits to encourage intense exercise programs or give any specific exercise recommendations while going through treatment.
But now here I am, a cancer patient receiving chemotherapy and suddenly I am faced with trying to figure out how to continue to do all of the things that bring joy to my life while going through this intense treatment, and exercise is one of those joyful things. I also want to know if there is a level of exercise that is not safe. Is there a line that can be crossed where exercise goes from being helpful to being harmful? Admittedly, intense speed work at the track and 20 mile long runs don't feel like the right thing to do at the moment, but I want to know what should I be doing? The discussion with the oncology nurse and the NCCN guidelines regarding exercise certainly suggested a very cautious approach to exercise while on chemotheapy. My priority now is to maximize the benefit of my treatment in order to have the best chance for cure, and I certainly don't want to do harm, but my gut tells me that the very conservative approach that I have heard so far may not be the best advice for me. So I have started to dig deeper into research on cancer patients who exercise during and after treatment. I have discovered that exercise may do so much more than simply bring joy to my life. It may help me to live longer.
This paper is a systematic review of numerous studies that have examined the impact of exercise on cancer patients: Cormie, P et al. The Impact of Exercise on Cancer Mortality, Recurrence, and Treatment-Related Adverse Effects Epidemiol Rev 2017;39:71–92
After a careful selection process, they included 32 epidemiologic studies and 4 randomized controlled studies for their review to address the question of how exercise impacts cancer related mortality and recurrence. They also included 64 studies to review in order to address the question on how exercise impacts cancer treatment related side effects. The key take away from this review was that there was trend for reduced risk of cancer recurrence and cancer related mortality for the cancer patients who exercised. Note that the studies that showed these results are observational studies which means that they compared outcomes for cancer patients who exercised and those who did not or had minimal exercise, rather than randomizing the patients to an exercise group or no exercise group. Therefore factors other than exercise may explain the observed results. For example, it could be that the patients who had less advanced disease were more able to exercise and therefore the cancer specific outcomes have more to do with the underlying cancer than the exercise. However, there are potential exercise specific reasons to explain the outcomes as well. It is possible that the patients who exercised had fewer side effects from their chemotherapy and therefore did not require dose reductions or delays in treatment, both of which are known to be important in achieving optimal results from treatment. Additional potential biologic reasons for improved outcomes for cancer patients who exercise include improving the tumor microenvironment which may result in improved transport of chemotherapy to the tumor.
This paper was encouraging to read. I realize that it may not be proof that exercise will increase my chance for cure, but I feel much more confident that my instincts are correct. Continuing to exercise while receiving my chemotherapy is important not only for my overall happiness, but better yet, may help me live longer. I'll take it!