Long-Term Breast Cancer SurvivalLong-Term Breast Cancer Survival

Comparisons of Low-Income Urban Neighborhoods in Ontario and

California, 1988 to 2006

Co-InvestigatorsCo-Investigators

Investigator Expertise ______

Kevin Gorey Social epidemiology

Karen Fung Biostatistics

Isaac Luginaah Medical geography

Caroline Hamm Medical oncology

Eric Holowaty Cancer registration/surveillance

Presenter DisclosuresPresenter Disclosures

No relationships to disclose

Funding sources:Canadian Institutes of Health ResearchAssumption University (Research Chair)

Manuscript statusThe Breast Journal (in press)

Why study breast cancer? It’s a Why study breast cancer? It’s a sentinelsentinel health care quality indicator. health care quality indicator.Relatively common over the life course

Effective screens and treatments exist

Timely diagnosis and treatment matter

Excellent prognoses can be expected

Node Negative Breast Cancer Treatment advances proliferated

Substantial 15-yr outcome variability

Political ContextPolitical Context

CanadaAnecdotes about health care failures

• Long waits & scare resources

Prevalent advocacy for private solutions

United StatesPrevalent under- & uninsured populations

Public options being considered

Scientific Context: Ontario-California Breast Scientific Context: Ontario-California Breast Cancer Care & Survival in Low-Income Cancer Care & Survival in Low-Income AreasAreas

Significant Ontario advantages, 1998-2006• Shorter wait-times & greater access to

radiation therapy• Better 5-yr survival (node +ve disease)

15-yr node +ve survival null, 1988-2006

No previous Canada-US study of long term node –ve breast cancer survival

Research Question: Hypotheses Research Question: Hypotheses

Have breast cancer care advances that proliferated during the past generation been enjoyed equitably by low-income Canadian and American women with the most treatable type of breast cancer?

Hypotheses:1. Significantly more such women in Ontario

survived 15 years after their diagnosis.

2. They enjoyed significantly better treatment access than their counterparts in California.

MethodsMethods

Comparison of Historical Cohorts:Urban Places in Ontario and California, Women Diagnosed Between 1988-1990

Followed Until 2006 (15 Years)

SamplesSamples

Enhanced Ontario and California Cancer Registries• Comprehensive (98%), reliable, validity• 95+% valid data for all study variables

Random samples stratified by large-small places • Toronto-San Francisco & Windsor-Modesto

Restricted to node –ve disease diagnosed 1988-90:• Analytic sample of 800 women

Comparable places defined by Census Bureaus• Census tract (CT) low-income prevalence

AnalysesAnalyses

Cohorts followed for all-cause 15-year survival (yes/no) until 2006

Age-adjusted, income-survival rate ratios observed within- and between-country income deciles

Confidence intervals based on the Mantel-Haenszel χ 2 test

ResultsResults

Within-CountryWithin-Country15-Yr Survival Rate Ratios (95% CIs)15-Yr Survival Rate Ratios (95% CIs)IncomeIncome Ontario Ontario California California High 1.00 … 1.00 …

0.88 (0.54,1.42) 1.00 (0.96,1.04)1.01 (0.88,1.16) 0.85 (0.56,1.30)1.10 (0.78,1.55) 1.01 (0.65,1.56)0.91 (0.54,1.52) 0.91 (0.65,1.28)1.05 (0.78,1.42) 0.56 (0.34,0.92)0.94 (0.55,1.62) 0.69 (0.48,0.99)

1.02 (0.65,1.61) 0.84 (0.53,1.33)1.09 (0.77,1.54) 0.84 (0.54,1.31)

Low 0.96 (0.60,1.54) 0.60 (0.37,0.97)

Between-Country Findings:Between-Country Findings:All Indicative of Ontario AdvantageAll Indicative of Ontario Advantage

Lowest income decile (N = 80): • 15-yr survival RR 1.66 (1.00, 2.76)

Vulnerable places (lowest 6th, 7th & 10Th income deciles, N = 240): • 15-yr survival RR 1.35 (1.01, 1.81)• Lumpectomy RR 1.86 (1.37, 2.52)• Adjuvant RT RR 1.75 (1.21, 2.53)

DiscussionDiscussion

SummarySummary

Low-income women with node –ve breast cancer in Ontario were advantaged on care and 15-year survival as compared to women in California.

In an era of treatment innovations, relatively poor women in Ontario gained access to them much more readily than did their counterparts in California.

Such access mattered in terms of their long-term survival chances.

LimitationsLimitations

1. Race/Ethnicity Alternative Explanation

Findings replicated among non-Hispanic white women in California vs. entire diverse Ontario sample

2. All-Cause vs. Cancer-Specific Survival

Findings replicated among women younger than 50 at diagnosis

Conclusion Conclusion

More inclusive health insurance coverage in Canada versus the United States seems the most plausible explanation for the large observed Canadian advantages on treatment access and survival.