As you’ve probably gathered by now, my approach to fighting against cancer is to make every waking moment a gesture of defiance against this goddamn illness. I’m pleased to say that this general approach parallels that of many survivors I know. To date, I have considered my rehabilitation efforts (physical and cognitive) to be supplemental to these efforts. That is, these activities are not anti-cancer per se, but rather an effort to get back to my baseline and back to doing creative productive work. Brisk activity and a sense of purpose being valuable by themselves, while simultaneously fending off the depression and listlessness that often plagues patients with cancer. As an aside, I’ll mention that for my particular brand of tumor, depression decreases median survival by about 66%. So, one must not discount the importance of staying active and positive. Fortunately, I haven’t had to take either radiation or chemo, so it’s been relatively easy for me to be productive and optimistic.
“Enriched environment reduces glioma growth through immune and non-immune mechanisms in mice” Nature Communications (2015). Garofalo S1, D’Alessandro G1, Chece G1, Brau F2, Maggi L1, Rosa A3, Porzia A4, Mainiero F5, Esposito V6, Lauro C1, Benigni G4, Bernardini G4, Santoni A7, Limatola C8.
This morning I stumbled on the paper linked above. The authors have previously shown that mice housed in enriched environments — larger cages with running wheels, other mice (for more social interactions), toys, etc. — have better outcomes in various models of peripheral cancers. Then they tested the same hypothesis for glioma. They housed mice in either enriched environments (EE) or standard environments (SE), and seeded their brains with glioma cells.
The results were striking. Nearby, I’ve re-posted Figure 1, where the authors show that total tumor volume is dramatically lower in enriched environments. As expected, reduction in tumor volume correlated with improved survival (Figure 1D). So, what’s the mechanism by which enriched environments improve cancer outcomes? It’s at least partly immunological: Natural Killer cells infiltrate the tumor more readily in the enriched mice. It’s also partially cell-intrinsic: glioma cells in the enriched environments are less likely to thrive and invade nearby tissues. Both of these outcomes are unquestionably desirable to me.
These effects are mediated in part by IL-15, a pro-inflammatory cytokine related to IL-2, and BDNF, a neurotrophin activated by novel experiences. Notably, exogenous application of either IL-15 or BDNF mimics the effects of an enriched environment, and blocking Natural Killer cell activity severely damps the anti-tumor effects of enriched environments.
The bottom line:
Enriched environments for mice offer many advantages over standard housing, notably opportunities for exercise, social interactions, and play. Exercise in particular has been shown to have a dramatic, positive effect on Natural Killer cell activity and anti-tumor immunity. Naturally, I have a vigorous exercise regimen in place already. Enriched environments may also be intrinsically less stressful for the wee mice, and therefore provide conditions in which their immune systems can perform their duty with more vigor. Naturally, I have a vigorous anti-stress campaign in place as well.
The thing I find so cool about this paper is the suggestion that learning and novel experiences may directly impact the immune system, and thereby increase the weight and potency of the anti-tumor immune response. When I asked my neuropsychiatrist for recommendations for a cognitive rehabilitation program, he replied: “anything, as long as it’s novel, and you enjoy doing it. If you happen to be a Civil War buff, I don’t want to catch you reading your hundredth book about Gettysburg.” This may be one of the cases where he was more right than he knew. Learning and novel experiences as a means to directly fight cancer cells – it’s a special moment when you discover you’ve been doing the right things from the very beginning.