‘Old’ cells could be the cause of cancer treatment-related side effects, according to new research.

The study, published in Nature, made the discovery when investigating a possible relationship between the number of senescent cells (cells that have stopped dividing) in mouse models and side effects incurred by four commonly used chemotherapy drugs.

Researchers found that those mice with higher numbers of senescent cells experienced more severe side effects.

The experiment was carried out by scientists from the University of Groningen in the Netherlands and the Buck Institute for Research on Aging in Novato, California who engineered mouse models in which senescent cells could be tracked, isolated and eliminated.

After exposing the mice to four commonly used chemotherapies, the team found that the drugs caused senescent cells to persist in non-cancerous tissue which in turn induced inflammation.

When these cells were eliminated post-treatment exposure, several side effects were reduced, alongside an improvement in bone marrow recovery, decreasing in heart dysfunction, and lowering of cancer relapse risk.

As many chemotherapy drugs interrupt cell division in both healthy and cancerous cells, the findings suggest that targeting senescent cells could make chemotherapy more effective and tolerable for patients.