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. 2017 Jan 13:356:i6673.
doi: 10.1136/bmj.i6673.

Effectiveness of flexible sigmoidoscopy screening in men and women and different age groups: pooled analysis of randomised trials

Øyvind Holme  1   2 , Robert E Schoen  3 , Carlo Senore  4 , Nereo Segnan  4 , Geir Hoff  5   6 , Magnus Løberg  2   7 , Michael Bretthauer  1   2   8   7 , Hans-Olov Adami  2   8   9 , Mette Kalager  2   8   7
Affiliations

Effectiveness of flexible sigmoidoscopy screening in men and women and different age groups: pooled analysis of randomised trials

Øyvind Holme et al. BMJ. .

Abstract

Objective: To compare the effectiveness of flexible sigmoidoscopy in screening for colorectal cancer by patient sex and age.

Design: Pooled analysis of randomised trials (the US Prostate, Lung, Colorectal and Ovarian cancer screening trial (PLCO), the Italian Screening for Colon and Rectum trial (SCORE), and the Norwegian Colorectal Cancer Prevention trial (NORCCAP)).

Data sources: Aggregated data were pooled from each randomised trial on incidence of colorectal cancer and mortality stratified by sex, age at screening, and colon subsite (distal v proximal).

Eligibility criteria for selecting studies: Invited individuals aged 55-74 (PLCO), 55-64 (SCORE), and 50-64 (NORCCAP). Individuals were randomised to receive flexible sigmoidoscopy screening once only (SCORE and NORCCAP) or twice (PLCO), or receive usual care (no intervention).

Results: 287 928 individuals were included in the pooled analysis; 115 139 randomised to screening and 172 789 to usual care. Compliance rates were 58%, 63%, and 87% in SCORE, NORCCAP, and PLCO, respectively. Median follow-up was 10.5 to 12.1 years. Screening reduced the incidence of colorectal cancer in men (relative risk 0.76; 95% confidence interval 0.70 to 0.83) and women (0.83; 0.75 to 0.92). No difference in the effect of screening was seen between men younger than 60 and those older than 60. Screening reduced the incidence of colorectal cancer in women younger than 60 (relative risk 0.71; 95% confidence interval 0.59 to 0.84), but not significantly in those aged 60 or older (0.90; 0.80 to 1.02). Colorectal cancer mortality was significantly reduced in both younger and older men, and in women younger than 60. Screening reduced colorectal cancer incidence to a similar extent in the distal colon in men and women, but there was no effect of screening in the proximal colon in older women with a significant interaction between sex and age group (P=0.04).

Conclusion: Flexible sigmoidoscopy is an effective tool for colorectal cancer screening in men and younger women. The benefit is smaller and not statistically significant for women aged over 60; alternative screening methods that more effectively detect proximal tumours should be considered for these women.

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Conflict of interest statement

All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: support from South-Eastern Norway Regional Health Authorities and by Sorlandet Hospital Kristiansand for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

Figures

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Fig 1 Colorectal cancer incidence in the three trials comparing flexible sigmoidoscopy screening with usual care. Data from the NORCCAP trial are presented as two separate trials because the control: screening participants ratio was higher in the 50-54 year age group (5.4:1) than the 55-64 year age group (3:1). M-H=Mantel-Haenszel fixed effect model
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Fig 2 Colorectal cancer incidence in the distal colon (rectum and sigmoid colon) in men, based on data from the three trials comparing flexible sigmoidoscopy screening with usual care. M-H=Mantel-Haenszel fixed effect model
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Fig 3 Colorectal cancer incidence in the distal colon (rectum and sigmoid colon) in women, based on data from the three trials comparing flexible sigmoidoscopy screening with usual care. M-H=Mantel-Haenszel fixed effect model
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Fig 4 Colorectal cancer incidence in the colon proximal to the sigmoid colon in men, based on data from the three trials comparing flexible sigmoidoscopy screening with usual care. M-H=Mantel-Haenszel fixed effect model
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Fig 5 Colorectal cancer incidence in the colon proximal to the sigmoid colon in women, based on data from the three trials comparing flexible sigmoidoscopy screening with usual care. M-H=Mantel-Haenszel fixed effect model
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Fig 6 Cumulative proportion of individuals diagnosed with distal (rectosigmoid) and proximal (oral to the descending sigmoid junction) colorectal cancer in PLCO, SCORE, and NORCCAP trials comparing flexible sigmoidoscopy screening with usual care
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Fig 7 Proportion of colorectal cancer (CRC) cases among men and women in the distal (rectosigmoid) and proximal colon (oral to the descending sigmoid junction) in the usual care groups in PLCO, SCORE, and NORCCAP trials. The age group indicates age at screening, and the distal/proximal ratio is calculated for the entire follow-up (median 10.5-11.9 years)
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References

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