Most of us treat it as a morning ritual or a way to get through a tough day. But can caffeine, the same stuff that perks us up after a cup of espresso, actually help fight cancer? A growing body of research suggests it might. A team of researchers from Wroclaw Medical University has presented a comprehensive review of the evidence linking caffeine to anticancer effects.
Not just a stimulant
Caffeine isn’t just an energy boost; it’s a biologically active compound that affects nerve, muscle, immune, and cancer cells. In the body, it acts as a blocker of adenosine receptors—a substance that inhibits cell excitability and has anti-inflammatory properties. By blocking this receptor, caffeine “disinhibits” a number of processes, including the release of adrenaline and cortisol, affecting immune function and metabolism.
It turns out that caffeine can also disrupt the life cycle of cancer cells, block DNA repair mechanisms, and increase sensitivity to chemotherapy. It can also have prooxidant effects—inducing oxidative stress, which can be dangerous for healthy cells but deadly for cancer cells.
“Caffeine can enhance the effects of chemotherapy and radiotherapy by inhibiting a key DNA repair pathway, which leads to the death of cancer cells,” says Dr. Nina Rembiałkowska from the Department of Molecular and Cellular Biology at the Wroclaw Medical University. “It also acts as an antagonist of the adenosine A2A receptor, which may support the immune system in fighting cancer. Additionally, caffeine has pro-oxidant properties in cancer cells, increasing their susceptibility to treatment.”
Caffeine as a therapy “booster”
As demonstrated by a review study by a team from Wrocław, caffeine may enhance the action of known anticancer drugs such as cisplatin, doxorubicin, and oxaliplatin. When combined with them, it increases the number of cancer cells that enter the path of irreversible damage and apoptosis, programmed cell death.
Interestingly, caffeine may also affect the immune system in the context of cancer. In tumor environments, the molecule adenosine often “slumbers” immune cells. By blocking its action, caffeine may restore the immune system’s ability to attack cancer cells. Studies in mice have shown that animals receiving caffeine developed fewer tumors and had a stronger immune response.
The dose makes the poison
Not everyone reacts to caffeine the same way. How quickly we metabolize it and how intensely it affects our nervous and immune systems depends, among other things, on variants of the CYP1A2 and ADORA2A genes. People with so-called slow caffeine metabolism have caffeine in their bloodstream longer, which may enhance its effects, both beneficial and potentially harmful.
“Two things surprised me while working on the review,” admits Dr. Rembiałkowska. “First, the effects of caffeine can vary dramatically depending on the dose: low doses have a protective, antioxidant effect, while high doses have a harmful, pro-oxidant effect on cancer cells.” “Second, a patient’s genetics can significantly influence the effectiveness and safety of caffeine. In some people, it may be more effective against cancer than in others.”
It’s important to remember: caffeine isn’t a miracle cure, and its effects depend on the context. In small doses, it can have a protective effect as an antioxidant. In large doses, it can, on the contrary, increase oxidative stress and cause side effects such as insomnia, hypertension, or heart rhythm disturbances.
“The effective caffeine doses in in vitro studies (100–500 µM) are significantly higher than those achieved after drinking coffee (around 10 µM after 200 mg of caffeine),” explains Dr. Rembiałkowska. “This means that the biologically active concentrations used in studies exceed what can be safely achieved by drinking coffee. Therefore, further research is needed to safely increase doses in clinical settings.”
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The Wrocław team’s publication doesn’t declare caffeine a cure for cancer. Instead, it points to its potential as a natural compound that supports treatment. If future research confirms these observations, it may turn out that what we drink out of habit today will become a part of therapy tomorrow, though likely not in the form of a pumpkin latte, but rather in a precisely dosed form.
Caffeine as a modulator in oncology: mechanisms of action and potential for adjuvant therapy
Rembiałkowska Nina, Demiy Alina, Dąbrowska Alicja, Mastalerz Jakub, Szlasa Wojciech
International Journal of Molecular Sciences, 2025, vol. 26, no. 13, p. art.6252 [24 p.]. DOI: 10.3390/ijms26136252
