A group of researchers in Japan says it has determined how colorectal cancer recurs in patients who have undergone chemotherapy.

The study, reported in the journal Nature, is raising hopes that new therapies will be able to prevent the recurrence of one of the most common types of cancer.

Keio University Professor Sato Toshiro and his colleagues artificially produced a small cluster of colorectal cancer cells using tissue from patients.

The researchers implanted the clusters in mice. Then, they monitored the cancer stem cells that were dyed with fluorescent markers.

The results showed that, when the mice were injected with chemotherapy drugs, some of the cancer stem cells evaded the medication by attaching themselves to the membrane that lines the colon and becoming dormant.

Once the chemotherapy was over, the group found that the dormant stem cells began multiplying again. It says a molecule named YAP served as the trigger that prompted the stem cells to exit the dormant state.

The researchers believe inhibiting the YAP molecule could prevent the return of colorectal cancer in post-chemo patients.

Professor Sato says a similar mechanism could explain how other types of cancer recur. He said his group will continue to engage in research, so that new medicines can be developed.