EP174 - Do Socioeconomic Factors Influence the Likelihood of Presenting with Advanced Rectal Cancer at Diagnosis?

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Purpose/Background: Previous studies have demonstrated an association between socioeconomic (SE) deprivation and poor survival in rectal cancer (RC). Patients experiencing SE deprivation may not benefit from CRC screening initiatives either because of limited access or lack of awareness. This study aimed to assess the association between SE determinants and advanced RC at the time of diagnosis.

Methods/Interventions: The National Cancer Database was used to identify patients diagnosed with RC between 2010-2021. All available SE determinants (income, insurance status, rurality and distance travelled to access care) were identified as exposures. Stage III and stage IV RC were the outcomes used to define advanced RC at diagnosis. Patients with missing TNM stage at diagnosis were excluded. Relevant patient, clinical and disease characteristics were included. Univariable tests of association were conducted between these exposures and advanced RC. Variables significantly associated with metastatic disease at the time of RC diagnosis were included in a multivariable logistic regression analysis, to assess the association between SE factors and advanced RC at the time of diagnosis, accounting for other important predictor variables.

Results/Outcomes: 40,460 of 193,782 patients (61.4% male, mean age 62.4 years; 20.9%) had stage IV RC at diagnosis and 64,798 patients (33.4%) had stage III RC at diagnosis. On adjusted analysis, private Insurance (OR 0.93, p=0.805), low income (OR 0.70, p=0.050), rural residence (OR 1.21, p=0.592), and distance traveled for care (OR 1.0, p=0.386) were not associated with presentation with metastatic RC at diagnosis. There were significant associations among presenting with metastatic RC and adverse tumor characteristics such as nodal involvement (N1: OR 1.68, p< 0.0001, lymphovascular invasion (OR 1.51, p< 0.0001), perineural invasion (OR 1.41, p< 0.0001) and KRAS mutation (OR 1.58, p< 0.0001). On adjusted analysis, private Insurance (OR 1.13, p=0.673), low income (OR 0.96, p=0.798), rural residence (OR 1.03, p=0.947), and distance traveled for care (OR 1.0, p=0.761) were not associated with presentation with stage III RC at diagnosis. There were significant associations between presenting with stage III RC and adverse tumor characteristics such as high tumor grade (OR 1.42, p=0.038), perineural invasion (OR 1.38, p=0.021) and tumor size (OR 1.01, p< 0.001).

Conclusion/Discussion: This study, conducted using a large, representative cohort from a national cancer database, found that income, insurance status, rurality and distance travelled to seek care were not associated with either stage III or stage IV RC at diagnosis. Instead, adverse tumor factors were the strongest predictors of advanced RC at time of diagnosis. This study is limited by the availability of data for marital status, patient education level, occupation, and other SE determinants. SE deprivation is associated with lower RC survival, but this study indicates that this finding is not solely due to presentation with advanced disease. Further studies are needed to explore discrepancies in treatment strategies among patients of different SE strata.