Abstract LB-164: Characteristics associated with nonreceipt of post-treatment surveillance testing in stage II and III colon cancer survivors and the subsequent relationship with overall survival and the cumulative incidence of cancer death
Authors: Hines Robert B. , Jiban Md Jibanul Haque , Lee Eunkyung , Odahowski Cassie , Wallace Audrey , Adams Spencer J. E. , Rahman Saleh , Zhang Shunpu 
Published: September 2020

Background: Recent studies have reported no survival benefit associated with more intensive post-treatment surveillance testing in colon cancer survivors compared to less testing. However, few studies have evaluated characteristics of patients who fail to receive any surveillance testing and the relationship with survival and cancer-specific outcomes. The purpose of this study was to assess the association between sociodemographic and clinical characteristics of stage II and III colon cancer patients with nonreceipt of surveillance testing and the subsequent outcomes of overall survival and the cumulative incidence of cancer death.

Methods: This was a retrospective cohort study of the Surveillance, Epidemiology, and End Results database combined with Medicare claims. Stage II and III colon cancer patients diagnosed between 2002 to 2009 and between 66 to 84 years of age were eligible. A minimum of three years post-treatment follow-up was required for inclusion. Receipt of recommended surveillance testing–including carcinoembryonic antigen, computed tomography, and colonoscopy–was assessed for each year of the required three year follow-up. Patients were categorized as having received any surveillance testing (Any Testing) vs. none (No Testing). Modified Poisson regression was used to obtain risk ratios for the relative likelihood of not receiving any surveillance testing. Cox regression was used to obtain estimates of 5- and 10-year overall survival. Modified Cox regression was used to obtain 5- and 10-year estimates of the cumulative incidence of cancer-specific mortality. In addition, subdistribution hazard ratios (SHRs) with 95% confidence intervals (CIs) were obtained for the cumulative incidence of cancer-specific and noncancer death.

Results: There were 16,009 stage II and III colon cancer cases available for analysis, of whom 8.6% (n = 1,382) received No Testing. Compared to patients who received Any Testing, colon cancer survivors who received No Testing were more likely to be older, black race, separated/divorced, diagnosed later (2007-2009), have state buy-in coverage, urban, reside in the West/Pacific regions, have stage III disease, not have received chemotherapy, and to have zero or ≥ 4 comorbid conditions. Within disease stage, patients who received No Testing were more likely to experience death to any cause and cancer death than survivors who received surveillance testing. Accounting for competing causes of death, No Testing patients also experienced an increased rate of 10-year cancer death that was greater for stage III patients (SHR = 1.84, 95% CI, 1.48-2.29) than stage II patients (SHR = 1.44, 95% CI, 1.15.-1.78).

Conclusions: This study identified characteristics of colon cancer survivors that were associated with failure to receive post-treatment surveillance testing. The No Testing group also experienced an increased risk of overall and cancer-specific death that was higher for stage III patients. Future studies are warranted to confirm these findings.

Citation Format: Robert B. Hines, Md Jibanul Haque Jiban, Eunkyung Lee, Cassie Odahowski, Audrey Wallace, Spencer J. E. Adams, Saleh Rahman, Shunpu Zhang. Characteristics associated with nonreceipt of post-treatment surveillance testing in stage II and III colon cancer survivors and the subsequent relationship with overall survival and the cumulative incidence of cancer death [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-164.