Rural-urban disparities in breast cancer survival in the context of the national breast cancer screening program for rural women in China

Background: Breast cancer is the most diagnosed cancer and is the second leading cause of cancer death among women in China. To improve early detection and treatment intake, China initiated a national breast and cervical cancer screening program targeting rural women aged 35 to 64 years, with an investment exceeding $220 million by 2018. This study aims to compare the survival risks between urban and rural women with breast cancer following the implementation of the screening program for informing valuable evidence and insights to future policy efforts. Methods: Data were extracted from the hospital and mortality records in Cheeloo Lifespan Electronic Health Research Data Library (Cheeloo LEAD), and it includes comprehensive medical information on patients across Shandong province. With an over 101 million population, Shandong accounts for about 7% of the national population, ranking as the second populous province in China. This study focused on eligible women aged≥18 years who have the breast cancer diagnosis in their hospitalization records between January 1, 2016, and June 30, 2020, and these records were linked to their mortality data. The final sample size included 99988 patients diagnosed with breast cancer. Urban-rural residency was determined based on patients ‘addresses, and age subgroup was categorized into 18∼34, 35∼64, ≥65 years aligned with the screening program. The Kaplan-Meier curves and Cox proportional hazards models were conducted to examine the associations between rural-urban residency and survival outcomes in the total sample and age subgroups. Age group, marital status, cancer stage, and surgical status were controlled as covariates. Findings: In the total sample of breast cancer patients, 64.69% lived in urban areas, and 35.31% lived in rural areas. Compared to urban patients, rural patients had higher proportions of being aged 35 to 64 (77.0% vs. 75.6%, P<0.001), being single (3.9% vs. 1.5%, P<0.001), having regional stage cancers (10.30% vs. 6.70%, P<0.001), and receiving surgical treatment (90.90% vs. 88.70%, P<0.001). Cox proportional hazards model found that there was no significant difference in breast cancer-specific survival between urban and rural patients (adjusted hazard rate [aHR] = 1.02, 95% CI = 0.95, 1.10). In the subgroup of patients aged 35-64 years, there was no significant difference in breast cancer-specific survival between rural-urban residence (aHR = 0.98, 95% CI = 0.92, 1.04). However, among older patients aged≥65 years, rural patients were associated with an elevated risk of breast cancer-specific death than urban patients (aHR = 1.11, 95% CI = 1.04, 1.18); among younger patients aged 18-34 years, rural patients were associated with increased hazard for breast cancer-specific death before adjusting covariates (aHR = 1.34, 95% CI = 1.24, 1.56), but the increased hazard was no longer statistically significant after adjusting covariates (aHR = 1.18, 95%CI = 0.96, 1.39). Interpretation: Our findings suggest that rural women aged 35-64 years, who are the targeting population of the screening program, did not exhibit a significant difference in survival when compared to their urban counterparts. It underscores the need to expand the screening prevention program, particularly for older rural women.