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10 Ontario Breast Cancer Screening (OBSP) Data

Ontario Breast Cancer Screening (OBSP) Data

Original source: Cancer Care Ontario
Distributed by:
1. Cancer Care Ontario
Suggested citation (see Data Citation Notes):
Ontario Breast Screening Program [years], Cancer Care Ontario

Data Notes

  • The OBSP is a province-wide organized breast screening program that ensures Ontario women aged 50 and over receive the benefits of regular mammography screening.  The program, in operation since 1990, is designed to increase the number of women who have regular breast screening so that cancers are diagnosed early when treatment is often easier and more successful.
  • The goal of the program is to achieve a 70% participation rate in Ontario women aged 50-69 by the year 2010 and 90% by 2020. 
  • The Program offers high quality mammograms and (at some locations) physical breast examination, plus:
    • accessibility (women can book their own appointments)
    • reminders to return to screening
    • close monitoring for follow-up of abnormal screening results 
  • Once a woman visits the OBSP she is very likely to return.  Over 80% of clients return for their recommended two-year re-screen.
  • The OBSP target age group is women aged 50-69, although screening is also provided to women aged 70-74 years. 
  • Women are not eligible for OBSP screening if they have had breast cancer or breast augmentation, or if they currently have symptoms of breast disease requiring diagnostic work-up.
  • Breast screening is provided through dedicated centres, affiliate sites in hospitals and independent radiology facilities, as well as a mobile breast screening coach in the Northwest.
  • Since 1990, more than 2.6 million screens have been performed for over 900,000 women and over 13,000 cancers have been detected, the majority in early cancer stages.
  • Biennial screening is adequate for most patients.  However OBSP provides annual screening for women at high risk of breast cancer.  The OBSP automatically invites women to be screened annually who have:
    • Documented pathology of atypical ductal or lobular hyperplasia or lobular carcinoma in situ 
    • A personal history of ovarian cancer
    • Two or more first degree female relatives with breast cancer at any age
    • One first degree female relative with breast cancer under age 50
    • One first degree relative with ovarian cancer at any age
    • One first degree male relative with breast cancer at any age
    • Breast density greater than 75% as seen on the mammogram
  • The OBSP does not currently screen women under the age of 50. There is evidence that there may be a benefit to screening women in their forties (17% reduction in mortality is estimated) however it is not as great as for women aged 50-69 (35% reduction in mortality is estimated for regular attenders). Women under 50 can be referred by their primary care provider to mammography facilities (local diagnostic sites) on a case by case basis.  These referrals are not included in the OBSP program or data tracking.
  • The OBSP carefully monitors quality standards.  Technologists undergo annual film reviews, while radiologists receive reports on their recall, positive predictive value, cancer detection, and interval cancer rates.  OBSP physics consultants monitor the mammography and film processing equipment.  Nurse examiners receive initial training in conducting clinical breast examinations and participate in ongoing education.  Province-wide data allow staff and facilities to see how they compare, identify areas for enhancement, and set goals for improvement.
  • In addition, all affiliate sites meet the accreditation requirements of the Canadian Association of Radiologists Mammography Accreditation Program (CAR-MAP).  This program sets the standards for mammography equipment, image quality, and staff skill level.  This accreditation program evaluates equipment and personnel once every three years.

References and Resources

  1. Cancer Care Ontario. Information for Primary Care Providers on the Ontario Breast Screening Program (OBSP), 2008. URL:
  2. Ontario Breast Screening Program. OBSP 2005-2006 Annual Report.
  3. Cancer Care Ontario. Insight on Breast Cancer. Volume 6, October 2007.
This page last updated: December 1, 2009
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