Cancer cells that survive treatment can remain in a latent state for several years before coming back in force in the form of metastases. According to a recent study, this awakening is caused by the presence of inflammatory conditions. They modify the environment of dormant tumors and provide them with the conditions necessary for their growth.
One of the most formidable aspects of cancer is its ability to survive therapeutic interventions, whether chemotherapy, radiotherapy or more targeted therapies. These treatments usually manage to eliminate almost all cancer cells. But the tiny proportion that manages to resist them can spread through the body, remaining in a dormant and undetectable form, much like a hunted enemy who slowly recovers his energies after a fight and plans his revenge.
The presence of these dormant residual tumor cells is very dangerous, because in addition to having preserved the characteristics which had allowed the initial tumor to invade a region of the body, these cells can form metastases which are now resistant to anti-cancer treatments.
The majority of cancer patients do not die from the initial tumor, but rather from metastases that develop in vital organs like the lungs, liver or brain. To avoid cancer recurrences, and at the same time reduce the mortality linked to this disease, it is absolutely necessary to prevent these residual metastatic cells from reactivating and expressing their destructive potential.
Inflammation awakens the sleeping enemy
The problem posed by residual cancer cells is particularly striking in the case of breast cancers that have estrogen receptors (ER+). Patients who have been treated for this type of cancer can be in remission for a very long time (sometimes more than 12 years), which suggests complete recovery, only to see the tumor suddenly reappear and threaten their life.
Several observations suggest an important role for chronic inflammation among the factors responsible for this awakening of dormant cancer cells. In breast cancer survivors, for example, elevated levels of C-reactive protein (a marker for the presence of inflammatory conditions) are associated with a significant reduction in survival. Additionally, certain conditions known to trigger inflammation, such as smoking, are also associated with an increased risk of recurrence and mortality in these patients.
The results of a study recently published in the very prestigious journal Science provide a better understanding of this link between inflammation and the development of dormant metastases. Using models of mice with breast metastases in the lungs, the scientists observed that the creation of inflammatory conditions using a bacterial molecule caused the massive arrival in the lungs of a class of white blood cells. (neutrophils) specialized in the elimination of pathogens.
Under normal conditions, the secretion of various enzymes by these neutrophils makes it possible to coat and digest the microorganisms rapidly. On the other hand, the researchers observed that when these phenomena occur near dormant tumours, they profoundly modify the environment in which the cancer cells are found. They cause, through a cascade of complex biochemical events, a “cellular awakening” leading to a rapid proliferation of metastases.
Anti-inflammatory lifestyle habits
The contribution of inflammation to cancer recurrence underscores how important it is for cancer survivors to adopt lifestyle habits that prevent the development of chronic inflammatory conditions.
In addition to quitting smoking, which considerably increases the risk of recurrence of several cancers, diet and physical activity are the main pillars of an anti-inflammatory lifestyle.
For food, it is particularly important to limit to a minimum the consumption of processed industrial foods, toxic aggressors
which generate a strong inflammatory response. Replacing these ultra-processed foods with foods of plant origin, rich in phytoprotective compounds, is therefore an essential prerequisite for reducing the risk of recurrence and maintaining good health in general.
The same is true for physical activity: a very large number of studies show that cancer survivors who are the most physically active are less at risk of recurrence, a protective effect that is particularly well documented for cancer. breast.
One should therefore not be fatalistic following a diagnosis of cancer and think that nothing can be done to prevent a recurrence. Eating plenty of plants, being physically active and maintaining a normal body weight can all reduce the risk of recurrence while improving quality of life.
Albrengues J et al. Neutrophil extracellular traps produced during inflammation awaken dormant cancer cells in mice. Science 361:pii:eaao4227.