Big Races / False Alarms

tl:dr don’t get CT scans or bloods analysed the week following a big race!!

Two new posts are coming up before 2023 is over. This one is about how some side effects from long-distance running can be mistaken both for possible symptoms of cancer progression and adverse effects of immunotherapy. Both these things have happened to me in the past year, which as you might imagine, has been somewhat unsettling. The second post will be about my coming to the end of my immunotherapy treatment, and what might the near future hold, in terms of disease management.

You all know that I run. A lot! 😬 I’ve been running every day now since January 1st 2020, and at the time of writing this blog post that means I’ve ran over 12,600 km. Since being diagnosed with stage 4 cancer in 2021 I took up running ultra-marathons, and the 100+-miler is fast becoming my favourite distance. I’ve blogged previously about the benefits of exercise, including running, on fighting cancer, and the growing field of exercise oncology. Exercise plays an important role in preventing cancer, in reducing tumour size, in helping cancer treatments work better, and lessening the impact of long-term side effects of the treatments. At the most basic level, exercise alters the body’s immune system, especially T-cells, and it seems that the more intense the exercise, the greater the anti-cancer effect. For example, physical activity increases anti-cancer immunity through increased regulation of T-cells in the tumour microenvironment. A major reason for my running every day is to boost my immune system, because I have no doubt that if my immune system is healthy, then I’m proactively helping the immunotherapy treatment attack the cancer cells.

However, what I wanted to go into in this post are the short-term effects of running ultramarathons, and how some of these effects appear, superficially at least, similar to signs of cancer (evidenced via CT scans) or potential liver damage from immunotherapy drugs (evidenced from blood biomarker analyses). As you might imagine, running ultramarathons leads to immense physiological stresses on the body, especially on muscles that connect to the skeleton, on the heart, liver, kidneys, and on the hormone, immune and respiratory systems; these have all been comprehensively reviewed by Knechtle & Nikolaidis (2018).

Unlike most people, having stage 4 cancer means that I undergo two CT scans approximately every 3 months: one for the head & neck, and the other for the chest. I also undergo analyses on my blood every three months to make sure that I’m healthy enough to receive my next infusion of Pembro, my immunotherapy drug. While blood cell types are measured (including those involved in your immune system), biomarkers are also measured, which act as an indicator of e.g. liver and kidney function.

The first false alarm came from a CT scan that I had shortly after running the Arc of Attrition last January, a 100 mile race around the coast of Cornwall (I blogged about that here). The scan showed two new areas of concern that had appeared on my lung, and it wasn’t clear from the scan if these were inflammation nodules or new tumours. Then it was a waiting game – if at the next scan three months later the nodules had increased in size, then they were most certainly new tumours. If however they had shrunk or disappeared (which was what actually happened) then they were just linked to inflammation. The same thing happened after I ran my first mountain ultramarathon up and around Snowdonia in May a few months later, leading to the second false alarm. I had a scan shortly after that race, and again a new bright spot was apparent in one of my lungs that was quite large. But when I had my next scan, this nodule had again disappeared.

More recently, I undertook an altogether different type of ultramarathon, this time seeing how many laps you can do round a 400m running track in Battersea – the Sri Chinmoy Self Transcendence 24 Hour Track Race London. I loved this race – I met such a wonderful bunch of people doing it, and unlike point-to-point races where you never see the best runners as they are so out in front, here you get to see how all other people run, the inevitable pain that everyone goes through, but their resilience as well.

I wasn’t due for a scan after this race, but I was due for my immunotherapy treatment the following week. Blood samples were analysed on the Tuesday after the race, and on Friday I had the Pembro infusion. But I also got a phone call the following week asking me to have my bloods redone as the previous samples contained high concentrations of the biomarker alanine aminotransferase (ALT). ALT is an enzyme that, when it increases in the blood, is indicative of liver damage. And for people on immunotherapy drugs, a rare adverse reaction can cause liver serious damage. So again, there was a bit of an agonising wait – if my body was finally having an adverse reaction to Pembro, then I would I have almost certainly have been taken off immunotherapy treatment.

However, ALT can also be produced by muscle damage. There have been many studies which have shown increased ALT concentrations in runners after ultramarathons. Recent research has suggested that elevated ALT concentrations in runners after an ultramarathon is more likely due to muscle damage caused by intense running than problems with the liver. And with recovery, said concentrations of ALT return to normal with little clinical consequence. And again, this was the case for my own blood test biomarkers, so that was the third and most recent false alarm.

So, I think the take home message for me from all of this is, not to get CT scans soon after a major race, as they are likely to give a false positive. Also, not to get bloods tested soon after a major race, as they may give a false positive for the body having a bad reaction to immunotherapy. Regardless, the last bit of advice is now just academic, as I receive my final ever infusion of immunotherapy next week, as my two years of licensed treatment are up. But more on this in the next blog post.