Abstract 36: Treatment patterns in stage I-III colorectal cancer patients over 65 years of age
Authors: Hardikar Sheetal , Weil Christopher R. , Lloyd Shane , Cohan Jessica N. , Supiano Mark A. , Ose Jennifer , Peoples Anita R. , Gupta Sumati V. , Pelletier Kaitlyn , Extermann Martine , Siegel Erin M. , Shibata David , Ulrich Cornelia M. 
Published: June 2022

Abstract
Background: Older patients (&gt;65 years) are frequently under-represented in clinical trials that determine cancer treatment guidelines. We sought to characterize treatment patterns among older patients and identify factors for receipt of non-standard of care (SOC) treatment.
Methods: The National Cancer Database (NCDB) was queried to describe treatment patterns in stage I-III colorectal cancer patients (2004-2017) over 65 years of age. Patients with metastatic disease and non-adenocarcinoma histology were excluded. SOC therapy was defined as any recommended treatment option listed within site- and stage-specific National Comprehensive Cancer Network guidelines. Clinicodemographic characteristics and treatment patterns were compared between colon and rectal cancer patients by ten-year age-groups. Multivariable logistic regression analysis was used to determine factors associated with receipt of treatment, by tumor site and stage.
Results: Of the 498,285 patients who met inclusion criteria, 47% were 65-75 years while 15% were &gt;85 years old (median age: 76 years). The majority were non-Hispanic White (88%), female (52%), Medicare insured (86%), colon cancer patients (76%) with a Charlson comorbidity index (CCI) of 0 (63%). Significant differences in treatment patterns by age were observed; for e.g., 11% of stage I colon cancer patients &gt;85 years of age did not receive SOC surgical treatment but rather received radiation-only treatment compared to only 2% patients 65-75 years of age who received radiation-only treatment. In logistic regression analyses adjusted for diagnosis year, sex, race/ethnicity, CCI, insurance, income, education, hospital type, treatment facility, rurality, and geographic region, older patients were more likely to receive non-SOC treatments for colon cancer stage I [OR(95% CI) for 76-85 years 1.31(1.23,1.40); &gt;85 years 3.41(3.17,3.66)], stage II-III [OR(95% CI) for 76-85 years 1.96(1.92,2.01); &gt;85 years 3.50(3.40,3.60)], rectal cancer stage I [OR(95% CI) for 76-85 years 2.06(1.89,2.24); &gt;85 years 6.36(5.77,7.02)], and stage II-III [OR(95% CI) for 76-85 years 2.14(2.07,2.22); &gt;85 years 9.02(8.33,9.77)] compared to 65-75 year old patients. Other predictors of receiving non-SOC treatments for both colon and rectal cancers included Black race (p&lt;0.001), CCI &gt;3 (p&lt;0.001), lack of insurance (p&lt;0.001), and treatment at a community cancer clinic (p&lt;0.001).
Discussion: Compared to 65-75 year-old stage I-III colorectal cancer patients, older patients at all disease stages are more likely to not receive SOC treatment. Other predictors for receiving non-SOC treatment are Black race, presence of comorbidities, lack of insurance, and treatment at a community cancer clinic. Future observational and randomized studies are needed to define the optimal treatment paradigms in older colorectal cancer patients, identify and address disparities, and better support these patients.
Citation Format: Sheetal Hardikar, Christopher R. Weil, Shane Lloyd, Jessica N. Cohan, Mark A. Supiano, Jennifer Ose, Anita R. Peoples, Sumati V. Gupta, Kaitlyn Pelletier, Martine Extermann, Erin M. Siegel, David Shibata, Cornelia M. Ulrich. Treatment patterns in stage I-III colorectal cancer patients over 65 years of age [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 36.