The Edinburgh randomised trial of screening for breast cancer: Description of method

Abstract

Summary Edinburgh was selected as one of the centres in the UK Seven-year Trial of Breast Screening of women aged 45-65 which began in 1979. Subsequently, our study was extended to a randomised trial with its own control population within the city. Half the practices were randomly allocated for screening, giving a cluster sampling of women. The total number in the trial is 65,000. Women with previously diagnosed breast cancer are excluded. Women allocated for screening are invited to the clinic and screened according to the procedures specified in the U.K. protocol, having clinical examination every year and mammography on alternate years. The two modalities of screening are assessed independently and the role of nurses is being evaluated. Breast cancer incidence is monitored by pathology register and the local cancer registry office and deaths from the General Register office. Long-term follow-up will be obtained through flagging at NHS Central Register. To determine the value of screening, standard statistical methods will be used to compare breast cancer mortality rates in the whole of the screening population with that of the controls. This trial has a power of 83% of detecting a reduction in mortality of 35% after 7 years of follow-up and a power of 95% of detecting a similar reduction at 10 years (oa=0.05, one-sided test).

Mammography screening in African American women

“…2,3,10 However, limited attention has been given to whether these results apply to African American women. To our knowledge, among the eight randomized clinical trials that have evaluated screening mammography, [11][12][13][14][15][16][17][18][19][20] only the Health Insurance Plan of Greater New York (HIP) Study 11 included a substantial proportion (approximately 20%) of black participants and provided race-specific results. 21,22 In a single report of race-specific survival rates, Shapiro et al showed that substantially more white than black women in the control group survived breast cancer five years from diagnosis (60.9 % versus 47.1 %).…”

The Edinburgh randomised trial of breast cancer screening: results after 10 years of follow-up

“…The tria popukuion Detailed methods have been described previously (Roberts et al, 1984 Alexander. Randomisation and screening The 87 practices were randomised to study or control status, which provided cluster randomisation for individual women who derived their status within the trial from that of their practice at entry. Women in the study group were offered screening, and those who attended (61.3%) underwent twoview mammography and clinical examination at their initial visit (prevalen screen).…”

“…Apart from the collection of medical information and screening histories at the screening clinic, follow-up of women in the two arms of the trial has been identical (Roberts et al, 1984(Roberts et al, , 1990. For the field-work period of the trial (1978-88) local follow-up for both breast cancer incidence and total mortality were used as independent data sources alongside flagging.…”

“…Following the trial protocol (Roberts et al, 1984), the main analysis has been of breast cancer mortality in the whole of the initial cohort for 10 years from survey entry. We also report the results of two subsidiary analyses focused on possible differential effects of screening women over and under 50 years of age.…”

Jones BA, Patterson EA, Calvocoressi L. Mammography screening in African American women: evaluating the research. Cancer. (2003) 97(1 Suppl):258–272.

“…3,10 However, limited attention has been given to whether these results apply to African American women. To our knowledge, among the eight randomized clinical trials that have evaluated screening mammography, [11][12][13][14][15][16][17][18][19][20] only the Health Insurance Plan of Greater New York (HIP) Study 11 included a substantial proportion (approximately 20%) of black participants and provided race-specific results. 21,22 In a single report of race-specific survival rates, Shapiro et al showed that substantially more white than black women in the control group survived breast cancer five years from diagnosis (60.9 % versus 47.1 %).…”