Much longer life and much more cancer predicted

Top life expectancy — currently a hardy 85 years for Japanese women — has yet to approach its limit and could reach 100 well before the end of the century, according to demographers Jim Oeppen of Cambridge University and James Vaupel of the Max Planck Institute for Demographic Research in Rostock, Germany, in a recent paper (Science 2002; 296:1029-1031).

But all is not rosy, as scientists evaluating cancer trends in the United States forecast that despite advances in prevention and early detection, the absolute number of cancers occurring in people aged 65 years or older will double within the next 30 years. The two forecasts together have profound social, economic and political implications. Life expectancy estimates play a key role in determining future pension and health care needs as well as other social programmes. Increases in average longevity of just a few years can produce large changes in the numbers of old and very old people needing such services. Oeppen and Vaupel argue that current government forecasts underestimate how long the average citizen will live. They say that official forecasters cling to the idea that the limit of the human life span has almost reached its limit, but that history suggests otherwise.

To reach their conclusion, Oeppen and Vaupel analysed life expectancies in countries around the world from 1840 to 2000. When the demographers plotted the top life expectancy of each year, they found that record life expectancy increased at the "extraordinarily linear" rate of 2.5 years per decade. And the steady rise shows no sign of levelling off in the coming decades. "There is no evidence that countries like Japan and France, which have the highest life expectancies, are slowing down," says Vaupel. "In fact, France and Japan have some of the most rapid improvements in survival of the very elderly."

If the trend continues, about six decades from now babies born in the country with the highest life expectancy may live to be 100. That surpasses all currently published projections of maximum average longevity including the highest, a United Nations estimate of 92.5 years.

At the same time, however, age is an important risk factor for a host of maladies including heart disease, diabetes, and cancer. In the annual US cancer report (Cancer 2002; 94(10): 2766-2792), the authors note that the future ageing of the population in the US will "dramatically" increase the number of cancers and the age of most cancer patients, creating "a growing demand" for more medical and supportive services. Similar scenarios are expected in other countries and with other age-related diseases, says Alexandre Kalache, director of WHO's Ageing and Life Course programme.

The non-industrialized world will be particularly hard hit. "In spite of all the poverty, prevailing problems, lack of access to services, malnutrition and infectious disease, the chances of reaching old age are increasing by the year, by the day even, in developing countries," Kalache says. "In 2050, 80% of the world's two billion old people will live in developing countries."

Governments are becoming more aware of the looming problems that greying populations pose. And some, such as Canada, Finland, Costa Rica and Botswana, are working towards solutions. According to Kalache, providing basic information and support mechanisms so that people can better look after themselves, family members and friends "makes a huge difference", since most health care occurs outside health facilities. Also key will be the continued improvement of the health and education of children and adults throughout life, so they will be more fit when entering old age. Says Kalache, "We must remember that the two billion elderly of 2050 are today's children and young adults."&nbsp

Charlene Crabb, Paris

World Health Organization Genebra - Genebra - Switzerland