Effect of NHS breast screening programme on mortality from breast cancer in England and Wales, 1990-8: comparison of observed with predicted mortality.
OBJECTIVE
To assess the impact of the NHS breast screening programme on mortality from breast cancer in women aged 55-69 years over the period 1990-8.


METHODS
Age cohort model with data for 1971-89 used to predict mortality for 1990-8 with assumption of no major effect from screening or improvements in treatment until after 1989. Effect of screening and other factors on mortality estimated by comparing three year moving averages of observed mortality with those predicted (by five year age groups from 50-54 to 75-79), the effect of screening being restricted to certain age groups.


METHODS
England and Wales.


METHODS
Women aged 40 to 79 years.


RESULTS
Compared with predicted mortality in the absence of screening or other effects the total reduction in mortality from breast cancer in 1998 in women aged 55-69 was estimated as 21.3%. Direct effect of screening was estimated as 6.4% (range of estimates from 5.4-11.8%). Effect of all other factors (improved treatment with tamoxifen and chemotherapy, and earlier presentation outside the screening programme) was estimated as 14.9% (range 12.2-14.9%).


CONCLUSIONS
By 1998 both screening and other factors, including improvements in treatment, had resulted in substantial reductions in mortality from breast cancer. Many deaths in the 1990s will be of women diagnosed in the 1980s and early 1990s, before invitation to screening. Further major effects from screening and treatment are expected, which together with cohort effects should result in further substantial reductions in mortality from breast cancer, particularly for women aged 55-69, over the next 10 years.
Blanks
R G
RG
Cancer Screening Evaluation Unit, Institute of Cancer Research, Section of Epidemiology, Sutton, Surrey SM2 5NG, UK.
Moss
S M
SM
McGahan
C E
CE
Quinn
M J
MJ
Babb
P J
PJ
D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000175:diagnosis / Q000188:drug therapy / Q000401:mortality*; D004739:England / Q000453:epidemiology; D004965:Estrogen Antagonists / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000706:statistics & numerical data*; D008875:Middle Aged; D016012:Poisson Distribution; D016032:Randomized Controlled Trials as Topic; D012680:Sensitivity and Specificity; D013629:Tamoxifen / Q000627:therapeutic use; D014852:Wales / Q000453:epidemiology
D004965:Estrogen Antagonists; D013629:Tamoxifen