Breast cancer cells.
A new study in mice has found that chemotherapy can cause some of the healthy cells surrounding a tumour to produce proteins that encourage the hardiest tumour cells to start growing more aggressively after treatment.
When the researchers, based at Taipei Medical University, National Institute of Cancer Research in Taiwan and the University of California, changed the way chemotherapy was given to a longer and lower dose regimen, they didn’t see this effect on the healthy cells.
Dr Erik Sahai, an expert in cancer cell biology from the Francis Crick Institute, said: “This adds to the growing evidence that cancer drugs can affect normal cells that are found within and around tumours. And these effects can make treatments less effective in the long run.”
Chemotherapy is usually given to cancer patients every few weeks at the “maximum tolerated” dose to kill as many cancer cells as possible.
And while this helps get rid of most of the cancer cells, one of the biggest problems is that a few hardy ones usually survive. These hardy cancer cells can help new tumours to form, which are often more aggressive and spread more rapidly to other tissues.
This finding could be an important clue into how chemotherapy also affects the cells in and around tumours, and how this may support the survival and growth of hard-to-kill cancer cells.
Giving the mice a longer, lower-dose regimen of chemotherapy improved the length of time the mice survived by stopping the healthy cells driving cancer’s re-growth.
Sahai added, “This early research in mice suggests developing treatments that shut down the signals made by cells surrounding tumours during chemotherapy, or even exploring the dose of chemotherapy itself, could reduce the likelihood of cancer recurring.”
The study is published The Journal of Experimental Medicine.
Chan, T. et al. 2016. Metronomic chemotherapy prevents therapy-induced stromal activation and induction of tumour-initiating cells. J Ex Med. doi: 10.1084/jem.20151665