Recently I published a paper on the effect of cannabis, the variable that I analysed was cannabis use disorder. Patients with cancer, with colon cancer, who had cannabis use disorder were dramatically more likely to have death within five years than patients that did not have cancer use disorder. So that is an example of a recent paper that I published in the area of addiction and cancer; I have other work coming out. I have also looked at other kinds of addictions, particularly substance use disorder diagnoses in cancer patients, dealing with tobacco dependence, other kinds of nicotine dependence as well as opioid use disorder and I’ve started to look a little bit at stimulant abuse and I found that there were a lot of associations there that may have implications for cancer care which I am working on looking at as well.

So primarily a lot of the papers that I’ve looked at merging the two concepts of addition and cancer have been among patients rather than among the general population, although I have done some studies and these are still forthcoming, they’re in the process of being done, that are showing that there are associations between individuals who don’t have cancer and who have substance use disorders who eventually go on to develop cancer.

The book that I’ve written is broadening the concept of addiction to cover a set of behaviours and people for which we don’t have a lot of data. This particularly pertains to the general public and what you might consider to be subclinical addictions. So these are not rising to the level of problematic kinds of consequences in a person’s psychosocial functioning that would rise to the level of an abuse disorder diagnosis but are still, neuro-scientifically speaking, activating the same pathways as an addiction and having consequences that are downstream from those behaviours that are raising the risk of chronic diseases, especially cancer, in the long-term after repeated exposure. So I am broadening the concept of addiction for the purpose of the book that I’ve recently published.

Can you talk us through some of the addictions you’ve looked at?

In the book, as well as in my research, I am looking at some very common addictions. So alcohol is an example of one that I look at in both my research and that I’ve looked at through the book, alcoholism, alcohol use disorder. So that has clear implications when it comes to the development of cancer. I’ve also looked at tobacco and tobacco dependence as nicotine is a highly addictive chemical. I’ve looked at nicotine both in my research as the chemical that results in the addiction to tobacco and the consumption of tobacco being associated very clearly with cancer, but also I am tackling nicotine both in that context but also as itself a stimulant that absent tobacco may have implications that increase risk for cancer. Such that this constant stimulation from a chemical stimulant itself and constantly being exposed to it day in and day out, even with absent tobacco, will prevent your body from engaging in restorative behaviours that will result in protective mechanisms that can prevent cancer. So you are no longer engaging with those protective mechanisms as a result of constant nicotine exposure.

A lot of this is theoretical. I will say that the biochemical linkages have been elucidated in the literature and they are there but there is limited evidence thus far that we have which conclusively can tell us that nicotine exposure constantly in the long-term will increase risk for the development of cancer, despite the biochemical associations existing. Part of the reason for that is because a lot of the ways that people consume nicotine absent tobacco are relatively recent in the form of things like e-cigarettes. So we are still collecting data on long-term consequences of that kind of exposure.

And you’ve also looked at social media and smartphone use?

One chapter in my book is called Digital Dopamine and the reason for that is because I wanted to devote a chapter to this very common kind of addiction. We know, because these applications and social media platforms were designed to encourage repeated behaviour through things like doomscrolling and going through your newsfeed looking for… It’s essentially very much analogous to a gambling addiction and may not have quite the same consequence as for a lot of people with severe gambling addiction but neurochemically you’re activating the same pathways, the mesolimbic dopamine pathway, because you are seeking as you scroll something interesting and eventually you’ll see something interesting, your brain enjoys that and then you continue to scroll and this cycle repeats and repeats over and over.

One adverse consequence of that neurochemically is the increased levels of cortisol that we see in the body and, as a consequence of that, a decreased ability of your body to engage in restorative mechanisms such as immunological and hormonal mechanisms that would decrease risk of cancer through things like proapoptotic behaviour or cells that are damaged.

In addition to that, particularly, I will say that the scrolling behaviours and the screen exposure at night will decrease secretion of melatonin which itself has protective effects on its own but in addition will have protective effects due to the ability to help us get to sleep and have an adequate amount of sleep which has other protective effects. So there are a number of different mechanisms associated with this screen addiction that will, repeated over time, or at least there is a scientific basis to suspect that repeated over time they will result in increased risk for various different cancers.

Is anyone collecting data on that?

In time this will be possible but it’s very difficult. So it’s very difficult to have a very clean comparison group. There’s almost nobody that is going to be completely absent screen exposure so a clean comparison group isn’t possible. In epidemiological studies what we can do is we can look at the dose response gradient, such that we’re looking at people with lower levels and higher levels of screen exposure. But even then it’s not necessarily going to be true that the exposure is going to be linear. So it’s very hard to tell from a scientific perspective just whether or not the studies that we’re going to be able to do on this, just how much light we’re going to be able to shed on the development of cancer.

So I’m hoping that in time we will be able to get some more data on this. Right now, this book and a lot of the thinking around this is based very much on the biochemical associations that we have observed.

What can be done to reduce addiction risk and associated cancer risks?

From a clinical perspective I will say in primary care I think it will be beneficial not only to suggest that we engage in better behaviours but that we counsel patients on the kind of barriers that are preventing them from engaging in those behaviours and perhaps to recommend some sort of therapy or behavioural counselling for individuals that find it very difficult to break poor behaviours. So simply saying, ‘Hey, it’s important for you to stop eating processed meat because it will raise your risk of cancer,’ there are some patients that are going to be convinced by that but that is, generally speaking, I would say, insufficient because this is, again, a neurochemical addiction that patients will have. So simply recommending that is insufficient, we need to talk about the barriers, we need to talk about taking gradual steps towards weaning off these behaviours that are going to increase risk of cancer.

Outside of clinical care I will say one thing that we can do as a society is raise awareness of these behaviours as not only being bad for long-term health but being addictive. So raising awareness of the addictive nature of these behaviours will get people to take the stickiness of the behaviours more seriously such that they understand, ‘Well, this is very serious. I need to start to first recognise whether or not I am experiencing an addiction to these behaviours and, second, once I do recognise that to start gradually weaning myself off of this behaviour, recognise that I am drawn to this behaviour in an addictive fashion and, as a result, I take a couple of days off and then maybe build up to five days off, a week off.’ And so on and so forth until you feel that you have more control over your own decisions and are less drawn to those poor behaviours in an addictive fashion.

So I think that raising awareness is a major step that we can take to improving the health of society and that’s one of the reasons that I wrote this book. I wanted to make people more aware of the addictive nature of these behaviours.

Anything else you’d like to add?

I don’t want anyone listening to feel that this book or my research places any blame on individuals. Certainly there is a role for individual choice – we can choose to do things that make us healthier. We have power over our own health, I believe that. But I want to acknowledge that from a very young age people are living in a society that pushes us towards these kinds of subclinical addictions, these kinds of poor behaviours, towards adopting them, normalising them, thinking that they are OK to engage in on an everyday basis.

When we’re talking about companies that benefit from our repeated transactions associated with these behaviours that are set up in this manner, we’re talking about societies that normalise certain behaviours like constant alcohol consumption which is not healthy for you. We are talking about lots of behaviours that are integrated into our society and as a result of that we continue to engage on them every single day and raise our risk for long-term disease. So I’m very careful in this book not to say that, ‘Hey, you are engaging in these behaviours and…’ I don’t say, ‘It’s your fault that you’ve gotten cancer as a result of engaging in these behaviours,’ I completely sympathise with the notion that people who are engaged with these behaviours are doing so because that is what is considered normal by the society that they live in, by the work culture that they are in, by the corporate behaviours in society around us.

That being said, we do as a society need to make changes and as individuals we need to try to be resistant to the kinds of norms that we have been conditioned to believe are OK. So that’s one thing I wanted to emphasise and I hope that we can make strides towards collectively building a better and healthier society that will allow us to live happier and healthier lives with lower rates of noncommunicable diseases, especially, as I’ve focused in the book, on cancer.