Skin cancer researchers in the US say they have got evidence that exposure to the sun may not be the sole cause of melanoma for people with red hair.
It has long been known that people with red hair are at higher risk of developing skin cancer than the rest of the population.
Now a group of US scientists say a study has found mice with red colouring developed melanoma without being exposed to ultraviolet (UV) radiation.
The researchers say that could mean skin pigmentation itself is a cause of melanoma, not just exposure to the sun.
Australian experts say the study is merely interesting and staying out of the sun is still the best and only way to protect against skin cancer.
Massachusetts General Hospital dermatology department chairman David Fisher led the team of researchers and says they were keen to study the fundamental causes of melanoma.
"We decided to model in animals what is considered one of the most common risk factors, which is having red hair and fair skin," he said.
"And so we did this by imitating the exact gene, the same gene that is linked to the red hair, fair skin in people using mice.
"What we discovered is that when we introduced this red hair gene, in the context of a mouse that had a predisposition to getting moles, but not really melanomas, that the red hair, fair skin background dramatically increased the risk of these moles instead becoming invasive melanomas.
"And the surprise was that this did not require ultraviolet radiation. We were seeing this in a circumstance without any UV exposure."
Dr Fisher says they were shocked that the mice were developing melanoma tumours before they were even exposed to the UV rays.
"We had to go into the laboratory with a little UV meter to be sure that the lights weren't, you know, inexplicably emitting UV radiation," he said.
"There appears to be a mechanism independent of UV through which the red pigment is actually causing the melanomas to form."
The study, which ran for three years, is now published in the recent edition of the scientific journal Nature.
Australia has one of the highest rates of skin cancer incidence in the world.
Dr Phillip Artemi, the secretary of the Australasian College of Dermatologists, says 80 per cent of skin cancers are directly attributable to sun exposure.
While he says the new study is interesting, but it has not been backed up yet, peer reviewed and cannot be considered conclusive.
"We don't know if this can be repeated, and so we're really a long way from being able to say there's something else as well as sun exposure that could be triggering melanomas," Dr Artemi said.
"Myself, as a dermatologist, I've not seen spontaneous development of melanomas.
"I've not seen these melanomas on protected skin such as that of the buttock, and it's always correlating, in the majority if not all the patients, with excessive sun exposure."
Dr Fisher says while the results do indicate the sun is not the entire cause of melanoma, he stresses it in no way means that people should stop protecting themselves from the sun's harmful rays.
"This is in no way refuting the importance of protecting oneself from sun exposure and from ultraviolet radiation," he said.
"In fact, we would suspect that ultraviolet radiation may even worsen this same mechanism. It may amplify this mechanism."
It is a sentiment that is echoed by the Cancer Council of Australia.
Terry Slevin is the chair of the National Skin Cancer Committee, and he wants to see further development of the study.
"If anything the research highlights the importance of those folks taking the measures that they can control to reduce their skin cancer risk," he said.
"What it does do is also add another scientific piece to the puzzle, which I'm sure they and subsequent researchers will follow up, to try and identify exactly what that is and then potentially.
"We'd hope something that can be done about that to help further assist those people reduce their risk of skin cancer."
He says sun protection is still the best way to prevent skin cancer.
"We know that the Australian summer is coming up... we're getting into the period of time where the UV radiation reaches extreme levels in the middle of the day," he said.
"Avoiding that UV exposure, particularly in that high UV time of the day, is an important strategy for all Australians to think about, and our red-headed friends particularly so."