Effect of mammographic service screening on stage at presentation of breast cancers in Sweden

Authors

  • Swedish Organised Service Screening Evaluation Group

    Corresponding author
    • American Cancer Society, Cancer Control Department, 1599 Clifton Rd. NE, Atlanta, GA 30329
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    • Authorship: Drafting Committee

      Stephen W. Duffy, Cancer Research UK and Queen Mary University of London. László Tabár, Central Hospital, Falun and University of Uppsala, Sweden. Tony H.H. Chen, National Taiwan University. Robert A. Smith, American Cancer Society. Lars Holmberg (Chair of management committee), Regional Oncology Center, Uppsala, Sweden. Håkan Jonsson and Per Lenner, Department of Radiation Sciences, University of Umeå, Sweden. Lennarth Nyström, Department of Public Health and Clinical Medicine, University of Umeå, Sweden. Sven Törnberg, Oncologic Center, Karolinska University Hospital, Stockholm, Sweden. Jan Frisell, Karolinska University Hospital, Stockholm, Sweden.

      Statistical Analysis

      Amy M.F. Yen, National Taiwan University. Li-Sheng Chen, National Taiwan University. Yueh-Hsiah Chiu, National Taiwan University. Chia-Yuan Wu, National Taiwan University. Hui-Min Wu, National Taiwan University. Chih-Chung Huang, National Taiwan University Jane Warwick, Queen Mary University of London. Levent Kemetli, Karolinska University Hospital, Stockholm. Patrick Chou, Queen Mary University of London.

      Project Leaders of the Screening Programs

      Stockholm Region

      Gunilla Svane and Edward Azavedo, Karolinska University Hospital. Helen Grundström and Per Sundén, Danderyd Hospital. Karin Leifland, St. Göran Hospital. Kerstin Moberg, Södersjukhuset. Tor Sahlstedt, Skärholmen.

      Umeå Region

      Pal Bordás, Norrbotten. Leena Starck, Västernorrland. Stina Carlson, Västerbotten. Håkan Laaksonen, Jämtland.

      Uppsala Region

      Shahin Abdsaleh and Erik Thurfjell, Uppsala. Birgitta Epstein and Maria Tholin, Örebro. Ewa Frodis, Västmanland. Ann Sundbom, Värmland. László Tabár, Dalarna. Mika Wiege, Sörmland. Anders Åkerlund and Bengt Lundgren (deceased), Gävleborg.

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Abstract

BACKGROUND

Previous results have shown a reduction in mortality with service screening in Sweden on the order of 40%. If the rate of tumors at a later stage were similarly reduced, this would give further support to the mortality findings.

METHODS

The rates of lymph node-positive cancers, of tumors >2 cm in pathological size, and of tumors of TNM stage II or worse before and after the introduction of screening were compared in 13 areas in Sweden, adjusted for changes in overall incidence during the period of study and stratified by age (40–49 and 50–69 years).

RESULTS

Data were obtained on a total of 23,092 cancers and 10,177,113 person-years of observation. In women exposed to screening in the screening epoch, there was a significant 45% reduction in tumors of size >2 cm compared with the prescreening (relative risk [RR] = 0.55, 95% confidence interval [CI]: 0.46–0.66) in the 40–49 age group, and a 33% reduction in the 50–69 group (RR = 0.67, 95% CI: 0.62–0.72). For lymph node-positive and stage II+ disease, there were smaller but still significant reductions. No reduction in incidence in later-stage disease was observed in the unexposed women in the screening epoch.

CONCLUSIONS

Screening has significantly and substantially reduced the rates of larger tumors and lymph node-positive breast cancer in Sweden, and the magnitude of the reduction is consistent with the reduction in breast cancer mortality. Cancer 2007. © 2007 American Cancer Society.

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