Chronic stress can wreak havoc on many body systems, it can disturb the normal functioning of the female and male reproductive systems, suppress the immune system, and put the body in a vulnerable state against many infections.
But can chronic stress be the main culprit in developing a malignant tumor (cancer)?
The answer to this question is really complicated and involves good ethics, a process of analyzing data, and making sure the latter is credible.
Cancer definition
Cancer at the very basic level is the extremely fast, uncontrolled cellular growth. In other words, it’s simply when a type of your cells keeps multiplying and creating new cells without any check point in a completely anarchic way.
The only time when we witness a cellular growth at this rate is during fœtal development. But unlike tumor growth, this type of growth is appropriate and strictly regulated. There are genes that get activated during this period that allow different types of tissues to be made and once this process is over, these genes switch off.
However, when these genes are activated later in life, cancer happens and they’ll be called « oncogenes ».
Now that we have a basic idea about what cancer is, let’s take a look at what can cause it.
Causes of cancer
- Carcinogens which are chemical substances that may trigger the development of cancer
- Radiation
- Xenobiotic
- Various toxins
- Carcinogenic food
- Oncoviruses viruses that mess up the cell’s DNA (e.g. Human Papilloma Virus or HPV) or provoke the organ to keep proliferating due to cellular death (e.g. hepatitis B and C viruses)
Cancer biology
Now that tumor cells are growing at an enormous rate, the new challenge for the cancer is to figure out how to feed these cells. Mystery solved, it sends signals to nearby blood vessels that make them proliferate and reach the cancerous cells to supply them with the necessary nutrients. This is termed angiogenesis.
Based on our understanding of this angiogenesis process, a new field of cancer treatment is emerging that focuses on synthetizing new angiogenesis inhibitor drugs in order to starve the tumor and make its surgical resection easier.
How the body fights off cancer
In the first stages of cancer, the immune system plays a major role in destroying the newly produced tumor. One particular type of cells, called Natural Killer cells, is the most important line of defense at this stage. And if that name isn’t cool enough, I don’t know what is.
Once the cancer has grown enough to seek more nutrients via angiogenesis, other defense mechanisms will surround the tumor in an attempt to starve it to death.
How does chronic stress affect this system?
Stress and the immune system
Science has established that chronic stress suppresses the immune system making the immune cells less effective in fighting off infections. And as I just mentioned, Natural Killer cells are crucial in the first stage of cancer.
So, this seems very straight forward. Chronic stress suppresses the immune system which leads to the ineffectiveness of the first line defense which in turn leads to cancer growth. Right? Well, not quite.
The idea of chronic stress being a culprit in developing cancer is so wildly believed. Everyone knows and trusts that stress can cause cancer, stress can induce cancer, accelerate its growth if it already exists, and cause relapses. So, what’s going on? Can stress cause cancer?
Lab rats and cancer
Experiments were conducted on lab rats where they were put under a lot of stress and that caused the cancer to grow faster.
These experiments only confirmed the already believed theory of the relationship between stress, the immune system, and cancer.
The problem in these experiments is that researchers injected tumor cells from rats who had cancer into healthy rats and then they observed for two parameters
Cancer occurrence: how many rats develop full blown cancer from the injected tumor cells.
Cancer progression: how fast does that tumor grow.
And we all know that cancer in humans doesn’t occur because of injected tumor cells. So, right off the bat, the credibility of these lab results is gone.
Epidemiology of the chronic stress-cancer relationship
Retrospective studies
In the year 2001, a paper study was published by a journal called psycho-oncology where a group of women who were just diagnosed with breast cancer answered this simple question: what do you think caused your cancer?
The answers were really diverse including carcinogens, viral infections, toxins…etc.
However, one answer stood up and it was statistically the top result. That answer was stress.
The thing is, these studies are highly problematic simply because we are humans, and when something awful happens to us, our memory preferentially focuses on bad things. Hence the unreliability of retrospective data.
An example of this type of studies is:
Personality type and increased cancer risk
There has been a long standing point that certain types of personality (e.g. introverts, repressive) increase the risk of cancer.
There is no clear evidence that supports this theory and all the studies conducted lack credibility.
Prospective studies
This type of studies in considered the gold standard in such cases and they’re vastly more difficult to conduct.
Basically, you follow a group of healthy people throughout the years and then see if they develop cancer. Along with the data collected on their lifestyles and habits, you can come up with a relatively credible data on what caused their cancer.
Many prospective studies were conducted and the vast majority of them came up with the answer: yes, there is a clear relationship between chronic stress and cancer.
The westren electric plant study
A classic study of this type was conducted on a large number of workers in a western electric plant in buffalo, New York City.
In this study the stressor taken into consideration was major depression and it appeared to increase the risk of cancer by 2 folds.
This was considered the ultimate proof of the relationship between stress and cancer.
Years after, more digging was done to analyze this data, what they found smashed the credibility of this study to the wall. The people working in these plants were developing major depression because they had a horrible boss who made them work in an unsafe carcinogenic environment.
Prospective studies about stress, the immune system, and cancer
What about the immune function? Does the immune system’s efficiency decreases when a person is under a lot of stress? Is there any prospective study that supports this claim?
The answer is yes.
However, the noticed decrease was not enough to increase your risk of developing cancer. You could catch a cold, sure. But not cancer.
For the immune deficiency to be enough to increase you risk of cancer, it has to be a full blown immune deficiency. Your immune system function has to be flat as in the case of AIDS, which indeed is known to increase the risk of having certain types of cancer.
Now, that we concluded that there is no reliable scientific evidence connecting chronic stress to higher risk of cancer occurrence. Let’s take a look at whether stress has anything to do with the rate in which an already existing cancer progresses.
Chronic stress and cancer progression
This is a wildly controversial topic, and the way to go about it is to intervene with cancer progression. In other words, grab a bunch of people who already have cancer, then do something to reduce their stress, and finally see if the progression of the tumor slowed down.
The David Spiegel study
The most popular study that supports this theory was conducted in the late 1980s by David Spiegel.
Here’s how it went.
Spiegel’s study included a group women who were diagnosed with breast cancer. He divided them into two groups.
The first group had standard medical treatment.
The second group had standard medical treatment plus the fact that they joined cancer support groups and attended the sessions regularly.
The results of the study
The results were staggering. The group of women who attended those group support had an average increase of 18 months survival rate compared to the other group.
To top this off, the underlying biology was also consistent with these findings. Support groups make the individual less stressed which leads to an enhanced immune system functioning. And as a result, cancer progression slows down.
Unfortunately, there was a loophole in this study. You see, patients who did not attend the support groups weren’t entirely complaint with the treatment regiment.
On the contrary, people who were consistently going to those sessions had support from other cancer patients and kept taking their medication regularly.
You might be asking yourself right now, why in the world would people stop taking their medication if it’s their only chance of survival?
The answer is simple. Chemotherapy medications have some serious side effects that will make you feel worse than the cancer itself.
So as far as we know, there is no clear relationship between stress and cancer progression.
Conclusion
In the end and based on the scientific research and data available to us, there is no concrete evidence that supports the existence of a relationship between chronic stress and a higher risk of cancer occurrence nor is there any evidence of decreased cancer progression if stress is removed from the equation.
So, the answer to the original question of this article: can stress cause cancer? Is no.
What saddens me is that there are some people out there, or should I say some predators that take advantage of these erroneous claims to their personal benefits. And sometimes, they can even be accredited physicians and celebrities.
What they try to do is sell you their stress management plan that will slow down the progression of your cancer or even heal it once and for all.
It’s simply bad information, bad medicine, bad ethics, and will ultimately lead you to have false hope and to drift away from the conventional therapy. So, shame on anyone who’d profit from people’s suffering.