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June 3, 2025
Christine Bürg
Molecular biologist Hanna Heikenwälder explains in the interview which preventive measures can protect against cancer and how AI assists in this.
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50 to 70% of all cancers could be prevented if the current state of research knowledge were properly implemented, writes Dr. Hanna Heikenwälder in her latest book "Cancer – The End of a Fear." And that's not all. The molecular biologist, who researches cancer and aging at the University of Tübingen, is convinced that everyone can protect themselves from disease: through prevention and their own lifestyle. In our interview, she talks about how we can live cancer-free in the future and what role AI and personalized medicine play in this.
Until now, cancer was considered an unconquerable disease. In your book, you give us all hope that in the future no one will have to die from it.
Exactly. It's about ensuring that no one has to die from it anymore. Eradicating cancer is impossible because mutations and thus DNA changes constantly occur in the body. The primary goal is to prevent people from suffering or dying from cancer.
For a long time, we couldn't cope with the incredible complexity of cancer, always lagging behind with our therapies while the tumors, especially the advanced ones, kept mutating. Through machine learning algorithms and AI, we can now handle this complexity. It's a matter of time how quickly we can implement this knowledge. And for that, we also need the help of politics and society as a whole.
Cancer is not a disease, but a process. What exactly do you mean by this statement?
I am aware that this statement is very provocative. Especially for people who are suffering from cancer. But it is important to prevent cancer. An illness always has an element of randomness. The word process describes it much better because cancer, like aging, occurs in every person and every living being. This includes fish and plants. Once you realize that cancer is a question of when and where rather than if, prevention measures gain a completely different value in our society.
© André Leisner
Cancer researcher Dr. Hanna Heikenwälder
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Only about 5 to 10% of all cancers are caused by hereditary genetic defects, while the remaining 90 to 95% are due to genetic changes we acquire throughout our lives. What triggers these changes?
To disable all the security and protection mechanisms of our body, it takes about five genetic changes in a cell for it to mutate into a malignant cancer cell. In most cases, we accumulate all these genetic changes throughout life, and carcinogens naturally play a role. Smoking, UV radiation, or alcohol, for example.
What many don't know is that there is a second type of cancer-causers, known as cancer promoters. These prevent genetically damaged cells from dying, as they normally would, or they promote the growth of these cells. And these cancer promoters are much harder to recognize. It can be lack of exercise because it harms the immune system, diet, or an altered sugar balance.
You can protect yourself from cancer promoters through prevention. For example, it takes decades of smoking to get lung cancer. It takes decades of sunbathing to develop skin cancer. But cancer promoters act permanently on all cells that have genetic damage, whether it is inherited, caused by my lifestyle or unhealthy habits, or, as in most cases, simply spontaneous and formed on its own.
This means that everyone carries precursors of cancer within them, but they do not necessarily mutate into cancer cells. What can each individual do to protect themselves from this?
Cancer diseases have an incredibly high number of unreported cases. Approximately 5% of men around 30 already have precursors of prostate cancer, and by the age of 69, it's almost 60%. In the intestine, these are polyps. Only a small proportion of these become malignant, about 11 to 15%. The fact is that cancer originates from normal body cells and every cancer has a stage where it is benign and well treatable. However, if you wait too long, it progresses to a malignant stage where it is extremely difficult or impossible to treat.
It is important that we distinguish the malignant from the benign precursor stages. In the future, AI will help us with this. For example, AI now recognizes skin cancer better than the dermatologist. I can feed mammography images into a database, along with other parameters like blood, etc., and see the progression.
If we were to implement this everywhere from now on, we could create incredibly informative algorithms with our technical capabilities in a very short time, which could tell us: this tumor will become malignant or this one is benign. These are patterns and information that AI recognizes and that we could not recognize with the human eye.
We have one of the largest research centers for AI in Europe in Tübingen. So we have the capabilities and don't have to wait for these innovations to come from other countries. We are responsible for generating them. We need to detect cancer and prevent painful therapies.
It is also interesting to note that aging is a protective mechanism against cancer. What does this mean?
When looking at the distribution of cancer diseases, it becomes clear that they go up over the course of life and reach their peak around 70, 80 years. One might think that cancer is a classic age-related disease. Which is true, but also the other way around. In fact, aging is a consequence of or an evolutionary protective mechanism against cancer.
The fact that our cells do not live forever and only have a limited division potential (they stop growing after about 50 divisions) is a brilliant mechanism of evolution. When the cell protective caps, the telomeres, are depleted, the DNA strand is exposed, which is a severe DNA damage. The affected cells do not die, but stop growing. These are called senescent cells.
When we are young, we still have a fourth immune system. It recognizes and eliminates these cells. So the immune system not only protects us from bacteria or viruses but also plays a very important role in the detection and elimination of cancer cells. The miracle of spontaneous healing, which we always hope for, actually happens thousands of times daily in our bodies, although we are not aware of it.
The problem in old age, however, is not only that we have accumulated many genetic changes but that one of the first organ systems to age is the immune system. And that is the fatal thing. The number of aged or damaged cells increases, while immune function declines.
To fight cancer, personalized medicine is needed. What exactly is meant by that?
In English, it is also called Precision Medicine, which means targeted. At the moment, cancer therapy is decided by tumor type, such as colon or breast cancer. Usually a standard therapy, although it is often known beforehand that it only works in 40% of patients. If it does not work, the next one is taken. With our current possibilities of gene sequencing and proteomics (the study of proteins), predictions could be made as to whether this therapy will work or not.
For this, we need AI because the amount of data is far too large for us to process. Cancer is a common disease, but each tumor carries different genetic changes, and each person brings different genetic predispositions, has a different immune system, reacts differently to medications, which also depends on the microbes in the gut.
We need to include all this knowledge in the therapy decision. This is what happens in a center for personalized medicine, whose core is the molecular tumor board made up of interdisciplinary experts – geneticists, bioinformaticians, pathologists, surgeons – who use data from machine learning algorithms to make the ideal therapy decision.
Not only can we treat patients more precisely, but we can also gather new knowledge, derive new drugs from it, and tailor an immunotherapy. What goes hand in hand with personalized medicine will exponentially accelerate our progress in cancer therapy because we can handle this complexity. We can anticipate resistances based on this data. Now it's really just a matter of implementation.
In your opinion, what is important and necessary to make your vision a reality where no one dies of cancer anymore?
Education is very important because we need society and politics for the implementation. I believe that prevention should start as early as possible, already in childhood. Schools are the ideal place because all children go to school. And it is also the ideal time to teach children routines that they can carry into their lives later – like brushing their teeth.
A daily exercise routine, for example, is not only good for cancer prevention but also helps reduce stress. It boosts mood and is good for the brain, improving concentration and performance. Exercise has so many benefits. It protects against more than 35 chronic diseases.
The WHO says school-age children should exercise for one hour a day. Why is this not happening in schools? I think there should be an incentive, an award for active schools, for sugar-free schools in the form of funding, for example. School nurses are also a great concept for me. They provide personalized prevention at a small scale.
Often you can already tell in childhood who will be the patients of the future or who needs more guidance. Also, a school subject on health where children learn what healthy food is, how the immune system works, what a vaccination is. But also: Where can I find help? Where do I go if I feel mentally unwell? Where to go if I feel physically unwell? We have already talked with the ministry in Baden-Württemberg about a weekly school subject on health.
Keyword: lifestyle measures that protect against cancer. Which are particularly important?
The lowest cancer risk and overall mortality is seen with a normal BMI. In terms of cancer risk, it should even be at the lower end. There are very large studies with 2 million never smokers, people who have never smoked. It clearly shows that being overweight increases the risk of cancer.
Only from the age of 80 does this effect level out. But that is not because being overweight suddenly protects, but because pathological processes increase with age and thus the effect of body weight becomes blurred.
So having a low body weight is important, as well as meal breaks, especially at night. The rule that one should eat breakfast like a king and less towards the evening is actually true. It's not just about the amount of calories. If you constantly snack, it leads to continuous insulin release.
Foods with a low glycemic index are indeed a good choice because they keep you full longer and ensure that carbohydrates are released into the blood more slowly. This has the advantage of avoiding high insulin peaks or excessive insulin release. And it reduces the risk of diabetes.
I often get asked if it's better to eat vegetarian. Yes, provided certain rules are followed. If you only eat pudding or sweets, it's obviously not healthier. But generally, plant proteins are more advantageous in terms of cancer risk compared to animal proteins. Red meat is considered probably carcinogenic by the WHO.
What role does sleep play?
A certain amount of sleep is important. The lowest cancer risk is observed with six and a half to seven hours of sleep, and the lowest overall mortality at about 7.5 to 8 hours. What many don't know: Too much sleep is also not healthy. With more than nine hours of sleep per night, overall mortality and cancer risk increase.
What preventive check-ups do you recommend?
In any case, the ones recommended by law or covered by insurance: colonoscopy, mammography, the prostate cancer early detection exam, and skin cancer screening. For women, the gynecological check-up is crucial, as well as breast self-examination, which is essential since a large number of breast tumors are detected by women themselves.
Also important: the Pap smear, which will be replaced by the HPV test in the future, as well as the HPV vaccination. The smear and the vaccination complement each other. It is important to vaccinate boys too because HPV doesn't only cause cervical cancer but also penile cancer and cancers of the mouth and throat. I recall Michael Douglas’s story, who fortunately made this known.
And what many don't know: Anal cancer is also very often HPV positive and most intestinal tumors develop in the last few centimeters of the intestine. This means that the HPV vaccination could likely reduce the death rates from tumors in the last section of the intestine. Unfortunately, so far, we have about 40% participation among girls, and much lower among boys, as far as I know, below 20%.
Frightening figures. Does this vaccination have side effects?
As with any other vaccination, there can be an autoimmune reaction.
50 to 70 percent of all cancers could be prevented if the current state of research was correctly implemented. Only 5 to 10 percent of all cancers are due to congenital genetic defects, while the remaining 90 to 95 percent are due to genetic changes that we acquire during our lifetime – and which we can influence through prevention.
The most important lifestyle factors for cancer prevention are:
The following preventive examinations are recommended:
Artificial intelligence is revolutionizing cancer detection with more precise diagnostics. AI systems can:
Through machine learning algorithms, personalized medicine becomes possible, tailoring therapies individually to each patient.
What are cancer promoters and how do they differ from carcinogens?
Promoters of cancer are factors that promote the growth of already damaged cells or prevent them from dying. Unlike carcinogens (such as smoking or UV radiation), which directly cause genetic damage, cancer promoters act on all cells with genetic changes. Typical cancer promoters are:
The advantage: Preventive lifestyle measures can protect against cancer promoters.
Question: What is meant by personalized medicine in cancer therapy?
Answer: Personalized medicine (also known as precision medicine) means that cancer therapies are tailored individually to each patient instead of being applied generally based on tumor type. Considerations include:
Using AI and molecular tumor boards from interdisciplinary experts, the ideal therapy for each individual patient is determined, significantly increasing the success rate.
Yes, cancer precursors are widespread and a normal part of the aging process. Examples:
This does not mean that all these precursors become cancer. Early detection and differentiation between benign and potentially dangerous precursors are crucial – in the future, AI will help here.
Aging and cancer are bidirectionally related:
Paradoxically, aging itself is a evolutionary protective mechanism against cancer, as cells cannot grow indefinitely. The problem: As the number of damaged cells increases, the immune system's ability to eliminate them simultaneously decreases.
The lowest cancer risk is observed at 6.5 to 7 hours of sleep per night. The lowest overall mortality is around 7.5 to 8 hours. Important: Too much sleep is also unfavorable – from 9 hours of sleep per night, both overall mortality and cancer risk increase again. So ensure a balanced sleep duration within the optimal range.
Yes, a vegetarian diet can reduce cancer risk, provided it is balanced. Important points:
A predominantly plant-based diet with whole grains, vegetables, fruits, and legumes is recommended.
