164P Adjuvant radiation therapy amongst immigrant and Canadian-born/long-term resident women with breast cancer

Appropriate adjuvant radiation therapy (RT) after breast cancer surgery is an important quality of care metric. Cancer treatment experience for immigrant women may differ due to challenges in navigating the health care system. This study compares the proportion of immigrant and Canadian born/long-term resident women receiving adjuvant RT and time to RT. A population-level retrospective cohort-study using linked provincial administrative databases was conducted including women >=18 years of age with Stage I-III breast cancer diagnosed between 2010-2016 in Ontario, Canada. Women were classified as immigrants using the federal database if they arrived in Canada in or after 1985, and as Canadian-born/long-term residents if they were born in Canada or arrived prior to 1985. Dependent variables (age, co-morbidity, socioeconomic factors, stage, and treatments) were collected. Data on proportion of women undergoing RT and time from surgery to RT was collected. Multivariable analysis was performed adjusting for dependent variables. Out of 54,090 patients, 46,930 (86.8%) were Canadian-born/long-term residents and 7,160 (13.2%) were immigrants. Immigrants were younger at diagnosis (54.3 vs. 63.0 years) and more often had Stage III disease (16.8% vs. 13.9%). Odds of receiving RT after breast conserving surgery (BCS) was 0.86 (95% CI 0.78-0.95), and 0.98 (95% CI 0.86-1.12) after mastectomy. Mean time from any surgery to RT was longer for immigrants (126.9 days vs. 117.1 days, p<0.001). Using a multivariable piecewise Cox regression model, excluding patients who received adjuvant chemotherapy before radiation, the hazard ratio for receipt of RT within 90 days for immigrants compared to Canadian long-term residents was 0.87 (95% CI; 0.83-0.92). Amongst immigrants, women from Latin America and the Caribbean had the longest wait times. There were no differences based on length of stay in Canada or immigration class. Our study demonstrates a lower proportion of immigrant women receiving RT after BCS compared to Canadian-born/long-term resident women in Ontario, and a longer wait time for adjuvant RT. Further research is needed to explore system, provider, and patient factors that may be driving this difference.