Dying cancer cells release particles post-chemotherapy that can turn healthy cells cancerous: Study

Mumbai: A study by the Tata Memorial Centre (TMC) in Mumbai has suggested that dying cancer cells release cell-free chromatin particles after chemotherapy and radiotherapy that can turn healthy cells into cancerous ones.

The study by TMC's Advanced Centre for Treatment, Research and Education (ACTREC) also suggests that cancer treatment protocols may need to include drugs/agents that deactivate, destroy cell-free chromatin particles released by treated, dying cancer cells.

According to the study, dying cancer cells release cell-free chromatin particles (cfChPs, or fragments of chromosomes) which can turn healthy cells into cancerous ones. Some of the cfChPs may fuse with healthy chromosomes and cause new tumours.

The recent study examined whether chemotherapy, radiotherapy, or surgery, which generate dying cancer cells, could contribute to the cancer's metastatic spread.

Researchers led by Prof Indraneel Mittra from the Translational Research Laboratory, TMC, ACTREC, grafted human breast cancer cells in immune-deficient mice to generate tumours.

The mice then received treatment in the form of chemotherapy, radiotherapy or surgery; half of them also received agents that deactivate or destroy cfChPs.

The researchers not only found the presence of human DNA (cfChPs) and cancer proteins in the mice brains, but observed that these had increased markedly after treatment, especially after chemotherapy and radiotherapy.

However, the mice that received compounds to deactivate or destroy cfChPs had minimal human cfChPs or cancer proteins in their brains.

Based on these findings, the researchers speculated that cfChPs, which may contain cancer-causing genes, and which have the ability to migrate through the bloodstream to enter healthy cells in other organs, may cause the metastatic spread of cancer.

Most importantly, the administration of cfChP-deactivating/destroying agents prevented their invasion into healthy cells thereby potentially preventing metastatic spread.

The TMC said although many patients are cured of cancer, this study uncovered a potential risk involved in current treatment practices of the dreaded disease.

While chemotherapy and radiotherapy may kill the primary tumour cells, they lead to the release of cfChPs from the dying cells, which can then enter healthy cells elsewhere in the body via the bloodstream and cause cancer there, said the study.

"These findings have important implications for cancer treatment policies. First, clinicians need to consider cfChPs as a potential cause of metastatic cancer spread, rather than metastasis being caused by migrating cancer cells. Secondly, cancer treatment protocols may need to include drugs/agents that deactivate/destroy cfChPs," it noted.

Further, adding cfChP-deactivating/destroying regimens could mitigate this problem and improve outcomes for patients, the study said