254 Young Onset Rectal Cancer: A Growing National Concern?

Abstract

INTRODUCTION: The incidence of rectal cancer in the United States is increasing at an alarming rate among patients under the age of 45 years. The objective of this study was to investigate the incidence, demographics, tumor characteristics, treatment, and survival of rectal cancer in patients under 45 years of age. METHODS: Data on young-onset rectal cancer between 2000 and 2016 was extracted from the Surveillance, Epidemiology and End Results Registry. The clinical epidemiology of these tumors was analyzed using SEER*Stat. Only malignant cases were included. American Joint Committee on Cancer (AJCC) staging was used. IBM SPSS Statistics was used for Cox proportional hazard regression modeling to determine predictors of survival. Survival was calculated for primary rectal cancer only. Cases in which survival duration was unknown were excluded. RESULTS: A total of 10,375 patients with young-set rectal cancer were identified where 54.7% were male. Median age at diagnosis was 40 ± 5.7 years. The overall age-adjusted incidence of rectal cancer between 2000 and 2016 was 1.24 per 100,000 per year. Incidence increased with age, with the highest incidence occurring in the 40–44 year age group. Over the 16-year study period, the annual incidence of rectal cancer increased by 3.0% in a given year. Most tumors on presentation were moderately differentiated (48.3%) while the most common stage at presentation localized disease (40.7%). Moreover, 78.4% of these tumors were surgically resected while 50.9% received radiation, and 60.6% received chemotherapy. One- and 5-year cause-specific survival for rectal cancer was 92.7% and 70.8% respectively. On Cox proportional hazard regression analysis, worse outcomes were noted with Asians or Pacific Islanders [HR] 1.12, 95% confidence interval [CI] 1.03–1.21, P = 0.011), and increasing N stage (N1 HR 1.18, 95% CI 1.10–1.28, P = 0.000). Surgical intervention reduced mortality by 30% (HR 0.70, 95% CI 0.65–0.76, P = 0.000), while radiation therapy reduced mortality by 15% (HR 0.85, 95% CI 0.78–0.94, P = 0.001). Chemotherapy did not significantly affect survival outcomes (HR 1.04, 95% CI 0.94–1.15, P = 0.452). CONCLUSION: Our study highlights an increasing incidence of rectal cancer in the younger population under the age of 45 years. Further research is needed in understanding factors contributing to this alarming rise, and inform screening guidelines aimed at decreasing the incidence and mortality of this potentially curable disease in this population.