Scientists have discovered wild Tasmanian devils that have recovered from the facial cancer that has decimated the species over the past 20 years.

Four devils in a wild population in the state's north-west contracted the Devil Facial Tumour Disease (DFTD) before successfully fighting it off.

Another two from the same population beat the cancer only to be reinfected, according to a report published in Biology Letters yesterday.

Researchers have been monitoring the population for more than 10 years, capturing and taking blood samples every three months.

Dr Rodrigo Hamede from the University of Tasmania said he hoped this was the beginning of a much brighter future for the devils.

"To find this small proportion of devils that can actually fight back and recover from DFTD, it is excellent news," he said.

"It is rewarding and it also puts the future in a more, sort of encouraging scenario."

Professor Greg Woods from the Menzies Institute for Medical Research said it was an "incredibly exciting" discovery.

"At first, we didn't believe it. We thought, 'Oh no, it must have been a misdiagnosis', but the evidence is quite convincing that the tumours did disappear," he said.

"Up until now we've had no evidence that devils could respond on their own to the tumour."

There is now evidence the devils are adapting to DFTD, says Dr Rodrigo Hamede. ( Supplied: UTAS )

Questions remain as to how the devils kicked cancer

Researchers have been analysing the population for several years and the animals that recovered are believed to have died from natural causes.

Professor Woods said they were still trying to understand exactly how they beat the cancer.

"These few devils seem to be able to modify the tumour cells so the immune system can recognise it," he said.

"We suspect that they produced chemicals called cytokines and that's what we're sort of testing in our laboratory at the moment."

There is now more hope a vaccine for DFTD will be effective. ( Supplied: UTAS )

Professor Woods said the discovery was an encouraging sign that a vaccine could be effective.

"It's important to make sure that we can do something to protect that other 90 per cent that don't appear to be responding," he said.

While the development is encouraging, researchers warned there was still a long road ahead.

"This is a response that occurred in the wild, in a very fast timeframe," Dr Hamede said.

"These evolutionary changes in response usually take hundreds of thousands of years."

The study supported the findings of another research project that found the species was evolving at a genomic level to protect itself.

"So this is another piece of information that the devils are actually adapting to coexist with DFTD," Dr Hamede said.

"Hopefully we'll start seeing more and more devils managing to resist DFTD or survive longer with DFTD."