Title: Life Expectancy and Cancer Risk

Key words: Mortality trends, death rates, cancer deaths, adenocarcinomas

Date: Aug 1999

Category: 13. Specific Conditions

Type: Article

Author: Dr van Rhijn

 

Life Expectancy and Cancer Risk

Introduction

Life expectancy has been extended in most populations in the world (73 years for men and 78.5 years for women in the UK1), and this has caused an increase in the elderly population. Individuals over 65 in the USA now comprise 12% of the population and this is expected to rise to 20% by the year 20302. As a consequence, the number of deaths attributed to cancer has steadily increased, especially in industrialised countries and among women3. Specific patterns of cancer vary considerably throughout the world and gradually changing trends in mortality from cancer at different sites are apparent4.

Trends

Female death rates from cancer show a slight increase over the last 20 years, largely restricted to older age groups, but the number of female deaths fell by about 1%. There has been a dramatic rise in deaths from lung cancer and a more gradual increase in ovarian and breast cancer. However there was a 3% decrease in breast cancer over 1987 – 1990, reversing the trend of the previous 5 years5. However, breast cancer is now responsible for 20% deaths in the UK6, and lung cancer for 16.5%, of which 80% are associated with smoking7. Deaths from colorectal, cervix and stomach cancer have declined8. Yet the age-adjusted incidence-rate estimate increased from 57.8 to 66.3 (15 percent) per 100,000 person-years for situ and invasive cervical cancer (1990-92). The greatest increase in the incidence-rate estimate occurred for women aged 65 to 69 years, from 40.1 to 63.2 (58 percent) per 100,000 person-years. The lifetime risk of developing cervical cancer increased from 4.6 (1 in 22) to 5.5 (1 in 18) percent9.

Although the overall death rates from cancer among British men have remained fairly constant since the 1970’s, there is a tendency towards a gradual increase according to the mortality statistics for 1987 – 1990. There is an increase in deaths from prostate, oesophagus, and pancreas cancer. Death rates from stomach, rectum, lung, trachea and bronchus have declined.

 

The proportion of cancer deaths (1965 – 1991 in USA) has risen from 16.3% to 23.7%, with a lifetime risk of developing cancer of 44.8% (men) and 39.3% (women) and the risk of dying of lung cancer is higher than for any other cancer10. The mean age at lung cancer diagnosis was 71 years (nearly 50 percent were adenocarcinomas)11. Cancers of the brain and other parts of the central nervous system, kidney, melanoma and non-Hodgkin lymphoma have all increased in people aged 55 and over. Cancers of the colon and rectum are the second most common cancers in the UK, as in all western societies, affecting up to 6% of men and women by age 75. Gallbladder cancer is more common in the older subjects12.

 

Conclusion

Cancer is a multifactorial and multi-stage disease13. Although the various studies (in different countries & at different time periods) present somewhat conflicting results, the trend is that an increase in life expectancy is associated with an increase in cancer risk.

References

  1. OPCS. Office of Population Censuses and Surveys. Population Trends. No. 68. London. HMSO. 1992c
  2. Garry, P.J. & Vellas, B.J. Aging and Nutrition. In: Ziegler E. & Filer L. Present knowledge in Nutrition. Seventh Edition. ILSI Press. Washington. 1996; Chapter 40 pp 414 - 419.
  3. Nutrition and Cancer. File No 12:; National Dairy Council. London 1995
  4. Davies, D.L et al. International trends in cancer mortality in France, West Germany, Italy, Japan, England and Wales and the USA. Lancet 1990; 336, 474 – 481.
  5. OPCS. Office of Population Censuses and Surveys. Mortality Statistics: cause 1990. Series DH2. No.17. London. HMSO. 1991a
  6. WHO, World Health Organisation. World Health Statistics Annual. Geneva: 1994
  7. Nutrition and Women’s Health: Fact File No 13:; National Dairy Council. London. 1996
  8. OPCS. Office of Population Censuses and Surveys. Mortality Statistics. Series Tables 1841 – 1990. Series DH1. No. 25. London. HMSO. 1993
  9. Merrill, R.M. & Feuer, E.J. Risk-adjusted cancer-incidence rates (United States). Cancer Causes Control. 1996; 7:5, 544 – 552.
  10. Garfinkel, L. 1995. Probability of developing or dying of cancer United States, 1991. Stat. Bull. Metrop. Insur. Co. 76:4, 31 – 37.
  11. Alavanja, M,C,. Attributable risk of lung cancer in lifetime nonsmokers and long-term ex-smokers (Missouri, United States). Cancer Causes Control. 1995; 6:3, 209 – 216.
  12. Zatonski, W.A. Epidemiologic aspects of gallbladder cancer: a case-control study of the SEARCH Program of the International Agency for Research on Cancer. J. Natl. Cancer Inst. 1997; 89:15, 1132 – 1138.
  13. Boyle, P. Nutritional factors and cancer. In: Garrow, J.S & James, W.P. Human nutrition and Dietetics. Ninth Edition. Churchill Livingstone. 1996; Ch. 54. pp. 701 - 713.