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Breast Cancer Screening Follow-Up Methodology

Breast Cancer Screening (Mammogram) Diagnostic Interval
Short description of Indicator Percentage of Ontario screen-eligible women with an abnormal OBSP screening mammogram who were diagnosed (benign or cancer) with a tissue biopsy within seven weeks of abnormal screen date
Rationale for measurement

While most women with an abnormal mammogram do not have breast cancer, additional assessment is required for definitive diagnosis.[1] 

Providing timely, well-coordinated follow-up with the appropriate interventions minimizes the fear and anxiety associated with abnormal results.[2] [3] [4]

Evidence/references for rationale
  1. Cancer Care Ontario. Ontario Breast Screening Program 2011 report. Toronto, Ontario: Cancer Care Ontario; 2013.
  2. Canadian Partnership Against Cancer. Breast Cancer Screening in Canada: Monitoring and Evaluation of Quality Indicators - Results Report, December 2009–January 2010. Toronto (ON): Canadian Partnership Against Cancer; 2015.
  3. Canadian Partnership Against Cancer (2015). The 2015 Cancer System Performance Report. Toronto: Canadian Partnership Against Cancer; 2015 June.
  4. Canadian Partnership Against Cancer. Report from the Evaluation Indicators Working Group: Guidelines for Monitoring Breast Cancer Screening Program Performance (3rd Edition). Toronto: Canadian Partnership Against Cancer; February, 2013.
Calculations for the indicator (Total number of Ontario screen-eligible women with an abnormal OBSP screening mammogram result, 50-74 years old, who were diagnosed within 7 weeks of the abnormal screen date if with a tissue biopsy/ Total number of Ontario screen-eligible women, 50-74 years old, with an abnormal OBSP screening mammogram and who needed a tissue biopsy for a definitive diagnosis) X 100
Standardized Rate Calculation N/A
Unit Percentage (%)
Data sources
  • ICMS (Integrated Client Management System) - OBSP mammograms and demographics, assessments
  • OHIP CHDB (Claims History Database) - Mastectomy claims
  • OCR (Ontario Cancer Registry) - Invasive and in-situ breast cancers
  • RPDB (Registered Persons Database) – Demographics
  • PCCF+ - Residence and socio-demographic information
Time Frame 2014 - 2017
Geographic Scale Provincial (Ontario)
Denominator description Total number of Ontario screen-eligible women, 50 to 74 years old, with an abnormal OBSP screening mammogram in the reporting period, who required a tissue biopsy (core or surgical) for a definitive diagnosis.
  • Average risk women, ages 50 to 74, who had an abnormal OBSP mammogram in ICMS
  • Mammograms were identified by OBSP mammogram records in ICMS for screening purposes
  • Women with abnormal program screening mammograms were identified as those referred for further testing by the screening radiologist in ICMS
  • All mammograms in ICMS were counted, including those with partial views

Exclusions:

  • Women with a final result of “unknown/lost to follow-up”
  • Women with a missing or invalid HIN, date of birth, postal code or LHIN
  • Women with a prior diagnosis of invasive or in-situ breast cancer before the index date; prior diagnosis of breast cancer was defined as: ICD-O-3 codes: C50, a morphology indicative of ductal carcinoma in-situ or invasive breast cancer, microscopically confirmed with a path report
  • Women with a mastectomy before the index date; mastectomy was defined in OHIP by fee codes E546, R108, R109, E505, E506 and R117
Numerator description Total number of Ontario screen-eligible women with an abnormal OBSP screening mammogram in a given calendar year who were diagnosed (benign or breast cancer) within 7 weeks of the abnormal mammogram date and required a tissue biopsy (core or surgical) for a definitive diagnosis
  • Date of diagnosis for benign cases was defined as date of last biopsy or procedure with benign finding
  • Date of diagnosis for breast cancer cases was defined as date of first FNA or tissue (core or open) biopsy procedure for breast cancer
Considerations  This indicator does not include OHIP billings for women screened outside of the OBSP since the OHIP database does not contain information about the results of the screening test or the results of the follow-up diagnostic work-up and final definitive diagnosis
Data availability & limitations
  • This indicator includes OBSP mammograms only.
  • There is an 8-month reporting lag for this indicator, as the sites have 8 months to close off assessment cases and enter the information in ICMS.
CSQI Year 2019