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Test, episode, and programme sensitivities of screening for colorectal cancer as a public health policy in Finland: experimental design

BMJ 2008; 337 doi: https://doi.org/10.1136/bmj.a2261 (Published 21 November 2008) Cite this as: BMJ 2008;337:a2261
  1. Nea Malila, director of Mass Screening Registry1,
  2. Tiina Oivanen, chief medical officer2,
  3. Outi Malminiemi, hospital chemist3,
  4. Matti Hakama, professor14
  1. 1Finnish Cancer Registry, Pieni Roobertinkatu 9, 00130 Helsinki, Finland
  2. 2Pirkanmaa Cancer Society, Tampere, Finland
  3. 3Centre for Laboratory Medicine, Pirkanmaa Hospital District, Tampere
  4. 4University of Tampere, Finland
  1. Correspondence to: N Malila nea.malila{at}cancer.fi
  • Accepted 9 September 2008

Abstract

Objectives To report the sensitivities of the faecal occult blood test, screening episode, and screening programme for colorectal cancer and the benefits of applying a randomised design at the implementation phase of a new public health policy.

Design Experimental design incorporated in public health evaluation using randomisation at individual level in the target population.

Setting 161 of the 431 Finnish municipalities in 2004-6.

Participants 106 000 adults randomised to screening or control arms. In total, 52 998 adults aged 60-64 in the screening arm received faecal occult blood test kits.

Main outcome measures Test, episode, and programme sensitivities estimated by the incidence method and corrected for selective attendance and overdiagnosis.

Results The response for screening was high overall (70.8%), and significantly better in women (78.1%) than in men (63.3%). The incidence of cancer in the controls was somewhat higher in men than in women (103 v 93 per 100 000 person years), which was not true for interval cancers (42 v 49 per 100 000 person years). The sensitivity of the faecal occult blood test was 54.6%. Only a few interval cancers were detected among those with positive test results, hence the episode sensitivity of 51.3% was close to the test sensitivity. At the population level the sensitivity of the programme was 37.5%.

Conclusions Although relatively low, the sensitivity of screening for colorectal cancer with the faecal occult blood test in Finland was adequate. An experimental design is a prerequisite for evaluation of such a screening programme because the effectiveness of preventing deaths is likely to be small and results may otherwise remain inconclusive. Thus, screening for colorectal cancer using any primary test modality should be launched in a public health programme with randomisation of the target population at the implementation phase.

Footnotes

  • We thank Minna Merikivi and Hilkka Laasanen from the Finnish cancer registry for coding and linking cases of colorectal cancer among the study population, the steering committee of the colorectal cancer screening programme at the Cancer Society of Finland, and the steering committee for screening of the Ministry of Social Affairs and Health, Finland for advice and administrative support in the planning of the programme.

  • Contributors: NM and MH designed the programme and analysed the data. TO and OM ran the screening centre. All authors critically reviewed the manuscript and approved the final version for publication. NM is guarantor.

  • Funding: The Finnish Cancer Foundation established a scientific post at the Mass Screening Registry The screening programme was funded by municipalities within the standard primary healthcare budget. The evaluation and analysis was done at the Finnish Cancer Registry.

  • Competing interests: None declared.

  • Ethical approval: The Ministry of Social Affairs and Health gave permission for implementation of the programme and registration of data in December 2003.

  • Provenance and peer review: Not commissioned; externally peer reviewed.

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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