That chemotherapy and radiation therapy can, in rare cases, trigger new cancers is not a secret of alternative medicine, but a long-known medical phenomenon. Professional organizations such as the American Cancer Society refer to these as treatment-related secondary cancers . Nevertheless, according to Canadian nephrologist and author Dr. Jason Fung, this risk is often not discussed openly enough with patients.
In a recent interview, Fung explains his view on cancer and its treatment. His central thesis: The drugs and radiation used to fight cancer can, through their cell-damaging effects, themselves promote cancer in the long term.
Cancer as a consequence of chronic cell damage
Dr. Fung, known for his book *The Cancer Code*, argues that cancer is not solely caused by genetic factors. In his view, cancer arises primarily as a reaction to long-term cell damage that puts healthy cells into a biological survival mode.
This perspective also has implications for cancer therapy. Both chemotherapy and radiation therapy work by selectively damaging cells. Cancer cells are usually more sensitive to this than healthy tissue – nevertheless, according to Fung, the treatment remains an intervention that also puts a strain on healthy cells.
The second cancer diagnosis years after therapy
Fung describes a scenario that is well known in oncology: patients successfully survive their first cancer, but develop a completely different type of cancer years later.
According to him, sufficiently intensive chemotherapy or radiation therapy can itself cause a new cancer about ten years later. The reason is the same mechanism that is at work with other known carcinogens – namely, the permanent damage to cells.
The comparison with asbestos
To illustrate this, Fung refers to asbestos.
It has been known for decades that asbestos can cause mesotheliomas, an aggressive form of pleural cancer, through chronic cell damage.
According to Fung, chemotherapy and radiation therapy are based on the same biological principle: both cause cell damage. The difference lies in the fact that this damage is deliberately accepted because the therapeutic benefit can outweigh the risk.
That is precisely why, Fung argues, patients must be openly informed that these treatments themselves can be considered carcinogenic.
The immune system often keeps cancer at bay for years.
In the interview, Fung also describes cancer as a process that constantly takes place in the human body.
In his estimation, hundreds or even thousands of potential cancer cells are created every day. The immune system recognizes and eliminates most of them.
As an example, he cites a patient whose melanoma was successfully removed. Decades later, the patient dies in an accident, his lung is transplanted – and the recipient develops another melanoma shortly afterward. For Fung, this is an indication that the immune system can keep cancer cells under control for many years.
From this he derives the question of what effect a therapy such as chemotherapy has on this natural immune surveillance.
A known but rarely discussed risk
Fung points out that the American Cancer Society explicitly recognizes therapy-related secondary cancers. Nevertheless, in his opinion, patients are often only given a brief or general explanation of this risk.
His criticism is not directed against chemotherapy or radiation therapy in principle. Rather, he calls for a more open approach to the risks.
In his view, these are effective medical weapons against cancer – however, their side effects and long-term consequences must be communicated fully and transparently.
A different perspective on cancer
At the heart of Fung’s model is the thesis that cancer is less a purely genetic defect than a biological adaptation reaction of damaged cells.
Chronic exposures such as smoking, asbestos, ionizing radiation – but also chemotherapy – could, in his view, trigger this process.
From this perspective, new questions arise not only regarding treatment but also prevention. At the same time, Fung poses the provocative question of whether alternative views on cancer are sufficiently discussed within the established healthcare system – or whether economic interests are partially hindering open debate.
