Cases of the disease, which mainly affects men aged between 20 and 50, have risen by 80 per cent since the Seventies but the latest figures show a levelling off, suggesting the cancer may have peaked. Doctors are baffled by the scale of the increase, from about 700 to 1,300 cases a year, but say changes in the diet and exposure to chemicals in the environment could be responsible.
A richer diet increases the amount of oestrogen made naturally in the body and the growth in obesity has paralleled the rise in testicular cancer. In addition, new industrial and agricultural processes have increased environmental exposure to xeno-oestrogens - chemicals that mimic the effect of oestrogen in the body. Denmark, one of the heaviest users of agrochemicals in Europe, also has one of the highest rates of testicular cancer, twice that in the UK.
Oestrogen plays a key role in the sexual development of both male and female foetuses but too much of it at the wrong time can hinder their development. It is known that the cancer is higher in first-born children and non-identical twins, which are naturally exposed to more oestrogen in the womb.
One theory has linked the rise with the introduction of the contraceptive Pill in the Sixties. This suggests that when the oestrogens in the Pill are excreted they enter the water supply, increasing the quantity of oestrogens to which pregnant women and new-born boys are exposed. However, studies have failed to confirm it.
The rise in testicular cancer is part of a worldwide increase in male sexual disorders including falling sperm counts and abnormalities such as undescended testicles and malformed genitals. A fact sheet on testicular cancer published yesterday by the Cancer Research Campaign shows wide variation in the incidence of the disease from less than three cases per 100,000 population in Finland to more than nine in Switzerland.
Professor Gordon McVie, director-general of the campaign, said the disease was more common in northern Europe than in the Mediterranean countries. It was also more frequent among whites than blacks, indicating a genetic factor. "Thankfully research advances mean that more than 90 per cent of men with testicular cancer can now be cured. But prevention is better than cure so it is important we find out why the number of sufferers is increasing so dramatically."
Dr Robert Huddart of the Institute of Cancer Research said that up to 30 per cent of men with testicular cancer may have a genetic predisposition, which makes them more susceptible, but that has been confirmed in only 2 per cent because researchers have been unable to trace families with a history of the disease. A search for the genes responsible is under way and the institute appealed for more families where at least two male relatives are affected to make contact.
A free leaflet about testicular cancer is available from the Cancer Research Campaign, 10 Cambridge Terrace, London NW1 4JL. Affected families willing to take part in research can contact Dr Huddart at the Institute of Cancer Research, 0181 643 8901 ext 3457.Reuse content