Doctors baffled by 50% cancer rise since 1971

Cancer is rising faster than can be accounted for by the ageing of the population and is likely to strike one in three of the population within their lifetime.

Cancer is rising faster than can be accounted for by the ageing of the population and is likely to strike one in three of the population within their lifetime.

The growing burden imposed by the disease, up by half since 1971, is revealed in figures published yesterday by the Office for National Statistics (ONS). They show the number of new cancers diagnosed each year increased from 149,000 in 1971 to 221,000 in 1997, or a rise of 72,000 annual cases.

Reasons for the increase have baffled doctors, dismayed researchers and now threaten future generations despite the hundreds of millions of pounds spent looking for the causes of the disease. The rise threatensthe government target of reducing cancer deaths by 100,000 in people under 75 by 2010.

Part of the rise is because of the ageing of the population and to improved data collection. Cancer is mainly a disease of the old and their numbers have grown sharply since 1971. Only 6 per cent of cancers among men and 9 per cent among women are in people under 45.

However, when the effect of the ageing population is taken into account, the figures show a real rise in the incidence of cancer of 20 per cent among men and 30 per cent among women since 1971, which remains unexplained. Most of the increase has been in the elderly - there has been little change in incidence in men under 65 and women under 55.

Progress in treatment has also been limited. There are now one million people diagnosed with cancer. Although survival has improved greatly for some cancers, - such as breast and testicular - overall survival has improved little. While death rates from heart disease, stroke and infectious diseases have fallen heavily over the past 50 years, deaths from cancer have fallen only slightly.

As mortality from heart disease has dropped, cancer has overtaken it to become the country's biggest killer. The disease became the most common cause of death among women in 1969 and among men in 1995, according to the ONS.

Overall, the number of people dying from cancer rose from 116,000 a year in 1971 to 133,000 in 1999, a rise of 17,000. The death rate initially increased among women before falling slightly during the 1990s. Among men, the death rate has fallen slowly since the mid-1980s.

One of the fastest-rising cancers is breast cancer, up by 45 per cent in women aged 45 to 64, and by one-third in older women. However, the death rate from breast cancer has fallen by 20 per cent in the past decade, largely owing to increased use of the hormonal drug tamoxifen and partly due to breast screening.

Testicular cancer, which affects chiefly young men, has more than doubled but bettertreatment has dramatically cut the mortality rate to fewer than 100 deaths a year.

The ONS report, published in Health Statistics Quarterly, divides cancers by social class, and says there would be 20,000 fewer cases if the differences were eliminated. Of these 80 per cent are caused by smoking.

Cancers more common in the rich are breast, prostate, brain, blood (leukaemia), skin (melanoma), lymphatic system (non-Hodgkin's lymphoma) and testicle. Cancers of the poor include lung, larynx, lip, mouth, oesophagus - all caused by smoking - and cervix, bladder, kidney, pancreas and stomach.