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Cancer Survival in First Nations People in Ontario Methodology

Cancer Survival in First Nations People in Ontario
Short description of Indicator Five-year observed survival : Age-standardized percentage of First Nations people alive 5 years after their diagnosis.
Rationale for measurement Observed survival helps crudely measuring the difference in survival among First Nations and other people in Ontario. Survival is important to understand several aspects of cancer control, including monitoring progress in treatment and early detection (i.e., screening).
Evidence/references for rationale

This is a well-established cancer burden indicator, described and reported on by numerous provincial, national and international organizations, including:

Additional evidence supporting the utility of this measure is described in:

  • Dickman PW, Adami HO. Interpreting trends in cancer patient survival. J Intern Med. 2006; 260(2):103–17.
  • Mariotto AB, Noone AM, Howlader N, Cho H, Keel GE, Garshell J, et al. Cancer survival: an overview of measures, uses, and interpretation. J Natl Cancer Inst Monogr. 2014; 2014(49):145-86.
Calculations for the indicator

Five-year survival (age-standardized):

  • Percentage of people alive at least 5 years after diagnosis
  • Age-standardized to the International Cancer Survival Standards (ages 15 to 74)
  • Survival was only analyzed among people 15 to 74 years of age. Data quality was poor outside of that age range.
Standardized Rate Calculation Percent survival was age-standardized to the International Cancer Survival Standard (ages 15 to 74).
Unit

N/A

Data sources
  • Ontario Cancer Registry (Ontario Health [Cancer Care Ontario])
  • Population data: Registered Persons Database (RPDB) and Indian Registration System (IRS) from Institute for Clinical Evaluative Sciences
  • The IRS was linked to the RPDB to identify First Nations people in Ontario. This linked file was then linked to OCR to identify First Nations people in Ontario with a cancer diagnosis between 1991 and 2010.
Time Frame Cancers diagnosed between 1991 and 2010
Geographic Scale Provincial
Denominator description N/A
Numerator description N/A
Considerations 
  • On October 29, 2014, the Ontario Cancer Registry Information System (OCRIS) was formally decommissioned and replaced with the new Ontario Cancer Registry (OCR). This change brings the registry in line with current Canadian and U.S. standards for tracking cancer incidence. The OCR now conforms to specific standards as set out by the National Cancer Institute’s Surveillance, Epidemiology and End Results (NCI SEER) program for counting multiple primary cancer sites, which most Canadian provinces and U.S. states now use. The adoption of specific NCI SEER standards with the new OCR has resulted in an increase in the incidence number of certain types of cancer reported in Ontario. To mitigate the impact of this change on survival estimates, relative survival estimates are based on 1 cancer case per SEER recode site group, per person as noted in the calculations section above.
  • Cancers were defined using U.S. Surveillance, Epidemiology and End Results (SEER) Recode definitions. Cancer definitions using SEER Recode may differ from definitions in other published analyses of survival, especially for cancers of the colon and rectum, and lung cancer.
  • For most cancer types, the full site grouping name outlined by the SEER site recode variable definitions was used. Short titles for the following cancers, however, were used for graphing purposes:
    • Lung and bronchus (ICD-O-3 code C34.0–C34.9): short title “Lung"
    • Colon and rectum (ICD-O-3 code C18.0–C18.9, C19.9, C20.9, C26.0): short title “Colorectal"
  • Age-standardizing 5-year observed survival allows for comparison across time and jurisdictions by adjusting for differences in the age-distributions of the populations of interest.
  • The Ontario Cancer Registry does not actively follow cases, so deaths may be missed. This, and the exclusion of individuals whose date of diagnosis is their date of death, may lead to overestimates of survival.
Data availability & limitations While relative survival is a stronger measure of survival experience, not all the information required for a relative survival ratio was available.