Rectal cancer in young patients: incidence and outcome disparities

Abstract

Background: There is an alarming rise in incidence among young patients with rectal cancer. The National Cancer Database (NCDB) and Surveillance, Epidemiology, and End Results Analysis (SEER) databases may help identify population level disparities in incidence and cancer-related outcomes.

Methods: A total of 197,178 patients within the SEER 18 registry and 221,886 patients from the NCDB database with rectal cancer were evaluated in this retrospective cohort study. The analyzed cohort consisted of young (<50), white or African American patients. Indication bias was mitigated by conducting inverse probability of treatment weighted analysis using binary logistic regression modeling to determine propensity score for being white or African American.

Results: A total of 6,144 young patients were identified from the SEER 18 registry and a total of 17,819 young patients were identified from the NCDB. From 1990 to 2016, there was a significant change in rectal cancer incidence, with a steadily increasing APC of 3.06 (P<0.05). The was no overall change in age-adjusted APC among young African American patients (APC 0.00, P=1); however, there was a significant increase among young white patients (APC 2.97, P<0.05). There was an increased incidence for both stage III and IV among young rectal cancer patients, with an age-adjusted APC of 5.35 and 3.83, respectively (P<0.05). After propensity score matching and inverse probability of treatment weighting, young African Americans had worse overall survival in both the NCDB and SEER (HR 1.1-1.3, P<0.05) databases. This disparity was also seen for cancer-specific survival (HR 1.5, P=0.002).

Conclusions: The current study adds to the growing body of literature demonstrating an alarming increase in incidence of rectal cancer among young patients. Moreover, the incidence appears to be increasing particularly among young white patients and driven by stage III disease.

Keywords: Rectal neoplasms; adjuvant; chemoradiotherapy; chemotherapy; cohort studies; propensity score.

Figure 1

CONSORT diagram demonstrating the inclusion and exclusion criteria used to select young rectal cancer patients using SEER 18 (A) and NCDB (B).

Figure 2

Age-adjusted annual percent change of incidence among young (<50) rectal cancer patients using the SEER 9 (A) and SEER 18 (B) registries. Age-adjusted annual percent change of incidence among young rectal cancer patients using the SEER 18 registry, stratified by race (C) and stage at diagnosis (D).

Figure 3

Overall survival for young rectal cancer patients, stratified by stage, in NCDB (A,C,E,G) and SEER 18 (B,D,F,H), after propensity score matching with inverse probability of treatment weighting.

Figure S1

Age-adjusted annual percent change of incidence in young rectal cancer using the SEER 18 registry for white (A) and African American (B) patients, stratified by stage at diagnosis.

Figure S2

Cancer-specific survival for young rectal cancer patients in SEER 18, stratified by stage I (A), II (B), III (C), and IV (D) after propensity score matching with inverse probability of treatment weighting.