I have been very fortunate – its been nearly three years since my diagnosis and I am NED (no evidence of disease, or the solid tumor equivalent of remission which is more commonly used for liquid tumors). I have not lost much function – can still work a full day and have a rich and enjoyable family life. The only fly in my ointment are my cold feet.
This isn’t news – I developed cold feet pretty soon after starting chemo, and thank the taxol for them. The technical term is Peripheral Neuropathy Caused By Chemotherapy, or chemotherapy neuropathy for short. It is caused by damage to peripheral nerves – the ones all around your body which are responsible for feeling pain, pressure, heat and so on. The peripheral neurons which are the individual cells that make up the peripheral nerves are very vulnerable to some chemotherapies because they are both long and don’t replace themselves very well:
- Long thin neurons: Taxol is a drug that targets the microtubules, which provide structure and move things through the cell. Some peripheral neurons are many inches long, and very thin, and they rely on the microtubule network to move nutrients and waster products around, and also to bring proteins, which are made in the cell body, to the distant parts of the nerve. The machinery is very cool – as you can see on the diagram, there are motor proteins called dynein and kinesin that literally walk up and down the microtubules, dragging cargo. It is easy to appreciate that when you destroy the microtubules (which the cancer cells are using to multiply) you are going to make the life of a peripheral nerve difficult.
- Neurons don’t replace themselves very well: unlike skin, for example, which is in the business of taking a hit and fixing itself, neurons live longer, are supported extravagantly by the body with glial support cells and are not replaced rapidly. One reason is that the work of a neuron is to make connections – they are often connected to many dozens if not hundreds of cells, and it is not easy simply replace. Compared to skin, which has a simple architecture, the difference is that of replacing a tile in your bathroom, and replacing the electric wiring in your house.
What has surprised me a little in regard to my cold feet is how persistent and consistent they have been. It has not gotten better in the past two-and-a-half years, and the feeling is there all the time. While going through my work day I do sometimes not notice it for prolonged periods, as my attention is focused elsewhere. But in moments when there is little sensory input – when waking up in the morning for example, it is there. This past weekend I went to Galveston with my family for a day out, and when I got in the car I was impressed by the contrast between most of me experiencing the sweltering heat (99 fahrenheit on the car’s thermometer, and Gulf Coast humidity added on) and my feet which were telling me they were blocks of ice.
The Army of Women is a program of the Dr. Susan Love Research Foundation, and is a crowdsourcing mechanism for clinical trials. You enter the data of your cancer, and they send you announcements of trials that may be relevant. And yes, they do include men! In fact, what first caught my eye in this email was that it said “women and men”. Thank you! The obvious snag that it also said “in Northern California” did not put me off – I joined the trial!
What does the trial do? There are two parts. In the first part the goal is to see whether certain genetic factors make you more susceptible to chemotherapy neuropathy, which could lead to a way for a test that would predict it. Then perhaps additional measures could be taken to offset the damage, or perhaps the therapy could be skipped altogether. I derived little benefit from taxol, for example – my tumor continued to grow through it. This first part takes just a few hours, where some blood is taken for the genetic analysis and some functional tests and questionnaires are administered.
The second part is the intervention, and this uses light to stimulate the peripheral nerves. It is based on work diabetic neuropathy by Swislocki et al, which shows that this can work, at least for some people with some symptoms. It turns out that the biggest effect was seen not for pain per se, but for tingling and itchy sensations. The “cold” I feel in my feet is much closer to tingling than pain, so this gives me hope that the intervention might be effective.
Furthermore, in the original work Swislocki and colleagues used 4 treatments for the diabetic neuropathy, but are now using 8 treatments for the chemotherapy related study. They had concluded in the first paper that more therapy might give better results.
The trial is placebo controlled – that means that participants will be randomly selected to receive either the photon therapy or a sham treatment that seems like it. This is necessary of course, and I hope that I get lucky…
My thanks to Judy Mastick, RN, MN, who is making it all happen for this trial and who helped me apply and arrange the time. Come breast cancer awareness month, I will be heading to San Francisco. Not sure yet about the flowers in my hair…