Researchers at the German University of Ulm claim that the opioid methadone may be key in treating cancerous tumors, Deutsche Welle reports.

The controversial idea has been discussed in the research department of the university hospital for several months. This news means that scientists have received the adequate backing and funding to investigate more clearly the possible effects of the drug.

"Our hypothesis is that methadone can make tumors more sensitive to chemotherapy," Professor Thomas Seufferlein told the Südwest Presse local daily in Ulm.

Seufferlin, the medical director of the university hospital, believes that methadone may be especially effective in combating intestinal cancer.

Read more: Fighting cancer with methadone - making chemotherapy more powerful

Methadone is an opioid which is often used to treat people with heroin addiction.

The therapy study will see whether methadone is effective in removing cancerous tumors. The German Cancer Aid organization is funding the project with €1.6 million.

The scientists are expected to announce the results of their research project in 2020.