Abstract P6-11-04: Trends and variations in female breast cancer along the Texas-Mexico border trends and variations in breast cancer along the Texas-Mexico border
Authors: Diaz Fernando Cristobal , Osuna-Salazar Elva Nora , Robledo Candace , Machiorlatti Michael , Sarhill Nabeel , Kwang Henry 
Published: March 2020

Background: Breast cancer is the leading cause of cancer death in Hispanic women. Compared to non-Hispanic Whites, Hispanic women are more likely to be diagnosed at later stages, with larger tumors and more likely to die from their cancer. The health disparities seen in the Hispanic population have been partially attributed to inadequate health insurance coverage and greater shortage of physicians, resulting in limited access to quality health care, lower cancer screening rates, and delays in treatment. The counties along Texas-Mexico border region, which occupy 1,254-miles of shared border and consist predominantly of a Hispanic population, share the worst health disparity statistics in the U.S. In this study, we investigate incidence and survival of breast cancer and explore whether these findings corroborate the trends seen in state and national surveillance reports.

Methods: We used publicly available female breast cancer cases in Texas between 1995-2015 made available from the Texas Cancer Registry. Chi-square tests examined the association between each categorical variable and border county status. Crude and age-adjusted incidence rates overall, invasive, and noninvasive were created for the state overall and by border status. To assess survival, unadjusted and adjusted median OS (95% CI) was calculated for overall and invasive/non-invasive female breast cancer by border status using Kaplan Meier survival analysis. Cox proportional hazards multi-variables models were also used to identify risk-factors that are associated with the difference in cancer survival rates overall and by border status.

Results: Adjusting for age, a decrease in the incidence ratio (IR) of overall and invasive female breast cancer is observed from 2000 to 2004 in border versus non-border counties followed by relative stability in the IR from 2005 to 2010. Without adjustment, relative to nonborder counties, border counties have a 7-month reduction in median overall survival (OS) for invasive cancer and 13-month reduction in median OS overall. After adjustment for age group, race, poverty level, grade and stage, Cox proportional hazard analysis revealed a lower hazard of death favoring border counties, 14% and 12%, respectively, for both invasive and noninvasive breast cancer (Table 1). Further stratification by neighborhood poverty level reveals no difference in the hazard of death amongst those within counties with poverty from 0-9.99%. However, for those belonging in lower poverty tracts, 10-19.9% and 20-100%, there is a 10% reduction in the hazard of death for both overall and invasive cancers that is statistically significant (Table 2).

Conclusion: Prior studies have demonstrated later diagnosis and worse outcomes in Hispanic women with breast cancer. Disparities notwithstanding, our results indicate that women of all races in a low poverty level (&gt;10%) and those living in the border counties have a significantly lower hazard of death. Further studies will examine the unexpected positive outcomes to identify potentially protective factors.

Table 1Cancer TypeUnadjustedAdjustedHRp-valueHRp-valueOverall1.08&lt; 0.00010.86&lt;0.0001Invasive1.0450.00040.86&lt; 0.0001Noninvasive1.080.09200.880.0158*adjusted for age group, race, poverty group, grade, stage, and year of diagnosis.

Table 2Cancer TypePoverty Level0-4.9%5-9.9%10-19.9%20-100%HRp-valueHRp-valueHRp-valueHRp-valueOverall1.110.27961.040.48610.900.00090.90&lt;.0001Invasive Cancer 1.110.32551.040.51960.900.0020.90&lt;.0001

Citation Format: Fernando Cristobal Diaz, Elva Nora Osuna-Salazar, Candace Robledo, Michael Machiorlatti, Nabeel Sarhill, Henry Kwang. Trends and variations in female breast cancer along the Texas-Mexico border trends and variations in breast cancer along the Texas-Mexico border [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-11-04.