Factors associated with screen-detected breast cancer across five Canadian provinces: a CanIMPACT study

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Mary McBride
Marcy Winget
Patti Groome
Kathleen Decker
Cynthia Kendell
Alyson Mahar
Eva Grunfeld
Published online: Aug 20, 2018


Introduction
Breast cancer screening is intended to identify cancer in early stages when prognosis is better and treatments less invasive.


Objectives and Approach
We describe Canadian inter- and intra-provincial variation in the percentage of screen-detected cases and identify factors related to having a screen-detected versus a non-screen detected breast cancer.


Breast cancers diagnosed from 2004/7 to 2010/11/12 in 5 Canadian provinces were included. Standard provincial datasets were created using screening program and claims data. A common algorithm (Alberta, Ontario) or variable from the screening dataset (British Columbia, Manitoba, Nova Scotia) was used to identify the mode of diagnosis (screening versus not). Relationship between screen-detected cancer and several demographic, clinical and healthcare utilization factors were explored.


Results
The percentage of screen-detected breast cancers varied from 25 to 40 percent across provinces; it ranged 43 to 51 percent for those aged 50-69. Within provinces, the percentage of screen-detected cancers varied across regional health authorities by a low of 1\% to a high of 33\%. Urban residence was positively associated with screen-detection in some provinces and negatively in others. Women in the lowest neighborhood income quintile had the smallest proportion of screen-detected cancers; the absolute difference from those in the highest quintiles ranged from 3.3-11.5\% across provinces. High continuity of care with a usual primary care provider was positively associated with having a screen-detected cancer compared to those with no usual care provider.


Conclusion/Implications
The proportion of screen-detected breast cancers varied significantly across and within provinces suggesting geographic variability in access to screening services. Variation across provinces in terms of factors associated with screen-detected breast cancer also likely reflect access issues. The positive association of high continuity of care with screen-detection in all provinces suggests that regular care with a primary care physician is an important factor in improving screening rates and detection.


Introduction

Breast cancer screening is intended to identify cancer in early stages when prognosis is better and treatments less invasive.

Objectives and Approach

We describe Canadian inter- and intra-provincial variation in the percentage of screen-detected cases and identify factors related to having a screen-detected versus a non-screen detected breast cancer. Breast cancers diagnosed from 2004/7 to 2010/11/12 in 5 Canadian provinces were included. Standard provincial datasets were created using screening program and claims data. A common algorithm (Alberta, Ontario) or variable from the screening dataset (British Columbia, Manitoba, Nova Scotia) was used to identify the mode of diagnosis (screening versus not). Relationship between screen-detected cancer and several demographic, clinical and healthcare utilization factors were explored.

Results

The percentage of screen-detected breast cancers varied from 25 to 40 percent across provinces; it ranged 43 to 51 percent for those aged 50-69. Within provinces, the percentage of screen-detected cancers varied across regional health authorities by a low of 1% to a high of 33%. Urban residence was positively associated with screen-detection in some provinces and negatively in others. Women in the lowest neighborhood income quintile had the smallest proportion of screen-detected cancers; the absolute difference from those in the highest quintiles ranged from 3.3-11.5% across provinces. High continuity of care with a usual primary care provider was positively associated with having a screen-detected cancer compared to those with no usual care provider.

Conclusion/Implications

The proportion of screen-detected breast cancers varied significantly across and within provinces suggesting geographic variability in access to screening services. Variation across provinces in terms of factors associated with screen-detected breast cancer also likely reflect access issues. The positive association of high continuity of care with screen-detection in all provinces suggests that regular care with a primary care physician is an important factor in improving screening rates and detection.

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