The occurrence of testicular cancer in New Zealand appears to be different to other parts of the developed world, particularly in relation to ethnicity and socio-economic status, according to a study undertaken by Wellington public health researcher Dr Diana Sarfati.
Her research shows that Māori men have much higher rates of testicular cancer than non-Māori and that men from lower-socioeconomic groups in New Zealand also have higher rates of the disease.
“This is the opposite to what is seen in the rest of the developed world where white men from upper socio-economic groups tend to have the highest rates of this cancer,” says Sarfati. “However, in New Zealand, Māori men have 50 per cent more testicular cancer than European New Zealanders, while Asian and Pacific males have 50 per cent less than Europeans. So there are big differentials according to ethnic groups.
“Whilst we shouldn’t expect rates by ethnicity in New Zealand to mirror image those of other countries, the fact that Māori rates are higher than European New Zealanders is curious in light of international data,” she says.
Sarfati’s study did not look at the reasons behind these differences; however, testicular cancer rates are increasing in all developed countries. It is unclear why this is so and why some groups have higher rates than others. It has been speculated that these trends relate to hormonal exposures in prenatal or early life, but so far the aetiology of testicular cancer is largely unknown.
The study is based on all 2,000 cases of testicular cancer taken from the New Zealand Cancer Registry among men aged 15 to 44 years between 1981 and 2004, linked to census data. It is part of a larger study investigating ethnic and socio-economic trends in cancer incidence in New Zealand, CancerTrends.
Testicular cancer is mainly a disease of young men, says Sarfati, but has excellent survival rates because it responds well to surgery and chemotherapy.
“Nevertheless, for young men and teenagers, in particular, this is a traumatic disease which takes quite a toll on their confidence and needs to be carefully managed.
“We need to carry out further investigation into why New Zealand is so different from the rest of the developed world in terms of patterns of testicular cancer following these intriguing results.”
Health Research Council