Doctors say they're sceptical of an Australian study showing women living further south have nearly the double the risk of developing breast cancer.
The study found breast cancer rates are nearly twice as high among women who live below 30 degrees latitude, compared to those further north.
All of New Zealand is south of 30 degrees latitude, but a Otago University academic says people should be cautious about interpreting the new research by the Westmead Breast Cancer Institute.
The Australian researchers suggested higher breast cancer rates among southern women could be due to comparatively lower levels of vitamin D, which is absorbed from sunlight.
Epidemiologist Professor Tony Blakely says it's a big jump to link breast cancer to vitamin D and such a dramatic difference in breast cancer rates between north and south would have been picked up previously.