Medical care is nowadays increasingly recognising the fact that we are all different individuals living in different environments, eat different foods, exercise to different extents and have different genes.
Indeed, evidence acquired over many years shows that these variations impact on our general health, susceptibility to various illnesses as well as our ability to respond to treatment when we fall ill. Whilst not much can be done about our genetics, improving our lifestyle is something that we can all work on.
Cancer is one example where risk of getting the disease and responding to therapy are associated with lifestyle choices. For example, the link between obesity and developing cancer is something that we are all beginning to appreciate and this goes for many indications including breast and pancreatic cancers.
The science behind this is still being studied but links have been made to the ability of tissue fat to cause a state of chronic inflammation thereby promoting a change in tissue cell type composition and biology that over many years encourages cancer growth.
Cancer immunotherapy is a breakthrough in patient care and it appears that treatment outcome, which depends on several factors, may also be influenced by our lifestyle choices.
- Diet
Our dietary choices are not only linked to obesity but they also impact the makeup of microbes in our gut. These creatures have their own way of processing nutrients and in doing so provide important metabolic intermediates that our bodies need to regulate important processes, such as food digestion, body weight and immune system activity.
Significant evidence shows that microbes in our guts have a say when it comes to our risk of developing cancer and to our responsiveness to cancer treatment including immunotherapy.
In general, a more diverse set of microbes rich in some beneficial bacteria predicts for a favourable outcome while a less diverse set of microbes containing harmful bacteria predicts for a less favourable response to a type of immunotherapy known as PD-1 inhibitors (these are drugs that boost immune cells’ ability to kill cancer cells).
The detailed science behind these fascinating differences are being unraveled but metabolism of nutrients through the microbes and production of key metabolic intermediates in our gut that may block or promote cancer growth is one way that is believed to be implicated here (with some metabolites themselves being linked to cancer progression and evolution over time). Microbes also impact overall immune system function and this is also likely to be implicated here.
One can imagine that eating various (healthy) types of foods to cater for the diverse types of gut bacteria for example, or rationing the use of antibiotics, may be one way to promote gut microbe diversity and this is what many researchers are looking at now.
2. Exercise
Not much needs to be said about the benefits of exercise on our general wellbeing in terms of keeping a healthy mind, cardiovascular and immune system. Exercise
is also beneficial in reducing cancer risk and preventing disease coming back. This could be due to some extent to the value of exercise in potentially reducing the level of some cancer-causing hormones.
Recent evidence in laboratory mice shows that exercise may aid tumour control through its ability to increase body adrenaline levels which in turn stimulate the recruitment of two important cancer-killing immune cell types known as T cells and natural killer cells to the tumour site, helping to reduce tumour burden.
One could envisage a situation where exercise could potentially help enhance the activity of cancer immunotherapy by turning an immunologically cold tumour hot (that is increasing the number and activity of cancer-fighting immune cells within it).
Whether such effects could be reproduced in human tumours remains to be seen but clinical trials are underway to investigate the impact of exercise in patients with cancer, aside from its other known benefits to overall health.
Improving our lifestyle is an easy and straightforward way to reduce our risk of illness and probably also improve our chances of responding to treatment when necessary. Many factors come into this but the more we know the more likely we are to be able to do something about it. As Benjamin Franklin put it, “an ounce of prevention is worth a pound of cure”.
References:
Routy et al, Science 2018
Gapalakrishnan et al, Science 2018
Pedersen et al, Cell Metabolism 2016
