Pollution could have contributed to a dramatic rise in the number of testicular cancer cases in England and Wales, according to the Cancer Research Campaign (CRC).

In a report published on Monday, the charity says the number of men developing the disease increased by more than 80% between the early 1970's and early 1990's - from around 1,700 to 1,300 new cases annually.

Scientists are now investigating the role of oestrogen as a trigger for testicular cancer and fear rising levels of chemicals in the environment that mimic this hormone may be to blame.

Doctors also think the genes that predispose men to testicular cancer may be far more widespread than previously thought.

Trigger factor

Testicular cancer expert, Dr Robert Huddart of the Institute of Cancer Research, Surrey, suggests: "Some studies show that cancer susceptibility genes, which have not been discovered, could be involved in up to 20-30% of cases.

"This latent risk factor could then be increased by another factor - such as exposure to oestrogenic compounds."

There is concern about oestrogen because research in the last two years shows a slightly higher risk of testicular cancer in first born sons and non-identical twins.

Experts already know that these children are exposed to higher oestrogen levels in the womb than older babies.

Controversial theory

However, the link between oestrogen-like chemicals in the environment and ill health is a highly controversial one. Some scientists believe that many ordinary chemicals used by industry and in the home have been slowly building up in the environment contaminating our water supplies.

Residues in the supply from the female contraceptive pill could also be involved.

The chemicals, in themselves or in combination, can mimic the effects of the female hormone oestrogen. They have been blamed for existence of male fish that have developed female genitalia and may even be behind the apparent fall worldwide of male sperm counts.

But although animal studies continue to raise concerns, no clear evidence has yet emerged to prove the link.

New research

At the moment, the only established risk factor for testicular cancer is having undescended testis.

But this accounts for only about 10% of patients, which is why the CRC is keen to identify other causes.

"Thankfully, research advances mean that more than 90% of men with testicular cancer can now be cured," says Professor Gordon McVie, the CRC's director general.

"But prevention is better than cure so it is very important that we find out why the number of sufferers is increasing so dramatically and, at the moment, we can only make informed guesses."

Family search

A research programme is now underway to find families with a history of testicular cancer.

Genetic factors have been confirmed in only 2% of testicular cancer cases so far, but the charity thinks the risks are much higher.

"There is evidence that these susceptibility genes are recessive and so a lot of people could carry them without realising it," says Dr Huddart.

Families with more than one member with testicular cancer and who wish to help the study can contact Dr Huddart at the Institute of Cancer Research on 0181 642 6011 Ext 3529.