Research led by University of the Sunshine Coast Professor Michael Kimlin has found the incidence of a type of testicular cancer in Australian and American men is linked to how far they live away from the Equator.

Professor Kimlin, who is USC’s Foundation Chair in Cancer Prevention, was senior author of the collaborative paper published in the Journal of Photochemistry and Photobiology.

“Very little is known about what causes testicular cancer, but our work found consistent patterns between Australia and the United States showing that sunlight and where men live appear to be important factors,” he said.

Professor Kimlin is a world-leading researcher into the environmental factors that lead to cancer.

The paper, ‘Germ Cell Testicular Cancer Incidence (GCTC), Latitude and Sunlight Associations in the United States and Australia’, was co-authored by academics from QUT’s AusSun Research Laboratory and School of Public Health and Social Work, Cancer Council Queensland and Griffith University.

Professor Kimlin said a statistical evaluation of white and black male populations in the two countries between 2001 and 2010 found the incidence of the cancer rose by one percent for each degree of latitude the men lived away from the Equator.

“The epidemiology of GCTC is unusual,” he said. “Although infrequent, incidence peaks sharply to dominate cancer risk in males aged 15 to 30 – an age range when cancer incidence is otherwise low.

“Geographically, GCTC incidence is higher in northern/north-western than southern Europe and lowest in southeast Asia and Africa. There is a strong genetic association with a gene variant associated with lighter skin colour.

“Our study compared Australia and the US because both are economically well-developed countries with similar lifestyles and largely European-origin populations.

“We observed a statistical association between latitude exposure and GCTC incidence, but can only speculate on reasons. Further research can examine whether Vitamin D is involved, for example.”

Dr Robert Biggar, a co-author from QUT, said: “Testicular cancer is a disease of young men, peaking in the early 20s and rarely beyond 30 years of age, so things that affect a man’s chance of getting it seem to happen in childhood.

“We found that men living in places near the Equator, north for Australians and south for the United States, had lower testicular cancer incidence. While there could be other explanations, sunlight is certainly one.”

Cancer Council Queensland spokesperson Katie Clift said about 150 Queensland men were diagnosed with testicular cancer every year.

“There is currently no routine screening test for testicular cancer, and little evidence to show testicular self-examination detects cancer earlier or improves outcomes,” Ms Clift said.

“Family history can increase the risk of testicular cancer – Queensland men should discuss their individual risk of the disease with their GP.

“The most common symptom is a painless swelling or lump in the testicle. Other less common symptoms include a feeling of heaviness in the scrotum or change in the shape or size of the testicle.

“Any Queenslander with questions about testicular cancer should call Cancer Council’s 13 11 20 or visit their GP.”

— Julie Schomberg