Fei, Naomi

Abstract Introduction: Colorectal cancer (CRC) is the second leading cause of cancer death in the United States (US). Primary care physicians (PCP) are critical towards a successful CRC screening program. However, the impact of availability of PCP on CRC-related mortality is not well studied. Materials and Methods: We extracted data on crude incidence and mortality rates of CRC among all 50 states and District of Columbia (D.C.) from the Center for Disease Control (CDC) WONDER database for the year 2019. Data on number of actively practicing PCPs in all 50 states and D.C. for the year 2020 were obtained from Association of American Medical Colleges (AAMC) State Physician Workforce Data Report. The correlation between the ratio of number of PCPs per CRC case with age-adjusted mortality rate (AAMR) for CRC was studied by state and within White and African American (AA) populations from 2017-2019. Pearson’s co-efficient was used to study correlations and T-test was used for comparing independent samples. Statistical analysis was performed using VassarStats. Results: The median AAMR for CRC from 2017-2019 in the US was 13.2 (IQR 11,15.4) per 100,000 population. AAMR for CRC was significantly higher among AA versus White populations (t=5.79, p<0.001). The national median PCP per CRC case ratio was 2.14 (IQR 1.46, 2.82). Higher state-wide PCP per CRC case ratio correlated with lower state CRC-related mortality (r=-0.36, p=0.011). PCP per CRC case ratio was significantly lower among AA as compared to White populations (t=-15.95, p<0.0001). Higher PCP per CRC case ratio correlated with lower CRC-related mortality among both White (r=-0.64, p<0.0001) and AA (r=-0.57, p=0.0002) populations. Using Fisher r-to-z transformation, we found no significant difference between the correlation of PCP per CRC case ratio with CRC-related mortality in White versus AA populations (z=-0.51, p=0.61). Conclusion: Results of this study suggest that greater availability of primary care physicians correlates with lower CRC-related mortality. AA have a significantly higher AAMR for CRC with a lower PCP per CRC case ratio. This may indicate a lower access to primary care among AA populations with CRC. Our results underscore the need to expand access to primary care among AA populations with the goal of minimizing disparities in CRC-related mortality. Citation Format: Udhayvir S. Grewal, Shiva J. Gaddam, Manik Aggarwal, Subhash C. Garikipati, Prabhat Kumar, Naomi Fei. Correlation of availability of primary care physicians and colorectal cancer-related mortality in the United States: Do racial disparities exist. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6488.

80 Background: Incidence of colorectal cancer (CRC) among adolescents and young adults (AYA) is increasing. A significant proportion of adolescents and young adults (AYA) with colorectal cancer (CRC) lack traceable genetic risk factors. We sought to study the impact of lifestyle-related risk factors on the incidence and mortality of CRC in these patients. Methods: We extracted data on crude incidence and mortality rates of CRC (reported per 100,000 population) for ages 15-39 years in all 50 U.S. states and District of Columbia from the Center for Disease Control (CDC) WONDER database (1999-2018). Data on risk factors such as obesity, physical activity, alcohol and tobacco abuse and nutrition were obtained from the Behavioral Risk Factor Surveillance System (BRFSS, 2020). Correlations were analyzed using Pearson’s co-efficient. p < 0.05 was considered statistically significant. Statistical analysis was performed using VassarStats. Results: Median crude incidence and mortality rates of CRC in AYA in the US from 1999-2018 were 3.8 (IQR 3.2, 4.4) and 0.7 (IQR 0.5,0.9) per 100,000 population respectively. States with higher age-adjusted prevalence of obesity per 100,000 had higher incidence (r = 0.36, p = 0.01) and mortality rates (r = 0.49, p = 0.0002) of CRC in AYA population. States with a higher age-adjusted prevalence of adherence to recommended weekly aerobic activity had lower incidence (r = -0.4515, p = 0.001) and mortality (r = -0.569, p < 0.0001) rates. While states with higher age-adjusted prevalence of tobacco abuse had higher incidence rate of CRC (r = 0.33, p = 0.02), there was no correlation with mortality rates (r = 0.24, p = 0.09). Higher prevalence of alcohol consumption was associated with decreased mortality rate (r = -0.44, p = 0.001), with no impact on incidence rate (r = -0.16, p = 0.26). States with lower daily consumption of fruits had higher incidence (r = 0.37, p = 0.01) and mortality rates (r = 0.59, p < 0.0001). No correlation of daily consumption of vegetables with incidence (r = -0.1516, p = 0.29) and mortality (r = 0.18, p = 0.22) rates was noted. Conclusions: In the current analysis, higher prevalence of obesity, lower rates of aerobic activity and lower daily consumption of fruits were strongly associated with increased incidence and mortality rates. The impact of tobacco abuse and alcohol consumption was more variable. Apart from improving access to genetic testing and counseling, efforts aimed at mitigating the rise of CRC incidence among AYA should also focus on traditional lifestyle-related risk factors.

Clinical trials reporting the robust antitumor activity of immune checkpoint inhibitors (ICIs) in microsatellite instability-high (MSI-H) solid tumors have used tissue-based testing to determine the MSI-H status. This study assessed if MSI-H detected by a plasma-based circulating tumor DNA liquid biopsy test predicts robust response to ICI in patients with pancreatic ductal adenocarcinoma (PDAC). Retrospective analysis of patients with PDAC and MSI-H identified on Guardant360 from October 2018 to April 2021 was performed; clinical outcomes were submitted by treating providers. From 52 patients with PDAC +MSI-H, outcomes were available for 10 (19%) with a median age of 68 years (range: 56–82 years); the majority were male (80%) and had metastatic disease (80%). Nine of 10 patients were treated with ICI. Eight out of nine patients received single-agent pembrolizumab (8/9), while one received ipilimumab plus nivolumab. The overall response rate by Response Evaluation Criteria in Solid Tumors was 77% (7/9). The median progression-free survival and overall survival were not reached in this cohort. The median duration of treatment with ICI was 8 months (range: 1–24), and six out of seven responders continued to show response at the time of data cut-off after a median follow-up of 21 months (range: 11–33). Tissue-based MSI results were concordant with plasma-based G360 results in five of six patients (83%) who had tissue-based test results available, with G360 identifying one more patient with MSI-H than tissue testing. These results suggest that detecting MSI-H by a well-validated liquid biopsy test could predict a robust response to ICI in patients with PDAC. The use of liquid biopsy may expand the identification of PDAC patients with MSI-H tumors and enable treatment with ICI resulting in improved outcomes.