The importance of age in screening for cancer

Objective-To derive a rational method of selecting the age range over which screening tests for cancer should be offered (that is, over which they wou ld be most effective in saving life). Main outcome measure-The number of person-years of life that are lost throu gh deaths occurring at each year of age from each of six cancers. Results-For each cancer the number of years of life lost to age 80, plotted against age at death, showed a rise followed by a fall. The peak indicates the age at which deaths from the cancer result in most years of life lost. Special screening tests, such as mammography for breast cancer, will be mo st effective in saving life shortly before that age. The peak (as a five ye ar age span) occurs at age 55-59 for breast cancer (189 years of life lost per 10 000 women per year), 70-74 for prostate cancer (114), 65-69 for colo rectal cancer (96), 55-59 for ovarian cancer (61), 50-54 for cervical cance r (47), and 45-50 for melanoma (8). The precise interval by which special s creening tests should precede the peak age is not critical; five years woul d be appropriate. Given current evidence on the efficacy of cancer screenin g, if it were stipulated that screening could only be performed when at lea st 50 years of life were to be gained per 10 000 persons screened, only mam mography for breast cancer would be conducted, between the ages of 50 and 5 9. if the stipulation was 25 or more years of life gained mammography would be offered to women aged 40-69 and cervical smears to women aged 35-59. Wi th only 10 or more years of life gained (unlikely to be worthwhile) mammogr aphy would be extended to women aged 30-74, cervical smears to 25-69, and f aecal occult blood testing for colorectal cancer offered to those aged 45-7 4. Extending cervical cancer screening to age 69 would save more years of l ife than the present policy of screening women aged 20-29. Extending breast cancer screening to the age of 74 would be more effective than cervical sc reening at any age. Conclusions-Determining the number of years of life lost through deaths fro m a particular cancer at each age is useful in public health screening poli cy, both in selecting the age range over which special screening tests of p roven efficacy should be offered and in quantitatively comparing the value of screening for different cancers.