Trend of anal cancer prevalence, risk factors, treatment, and mortality in different age groups based on National Inpatient Sample Data from 2016 to 2020.
Authors: Oh Youjin , Gajjar Rohan , Vallejo Alejandro , James George Lina , Turk Ekrem , Olafimihan Ayobami Gbenga , Sueldo Alexandra , Deenadayalan Vaishali , Vinod Solipuram , Gupta Shweta 
Published: June 2024

e15504 Background: Anal cancer is on the rise, yet the precise contributors to this trend remain unclear. This study aims to elucidate the evolving epidemiological landscape of anal cancer, focusing on risk factors, treatment modalities, and mortality trends across distinct age groups. Methods: We analyzed the Nationwide Inpatient Sample (NIS) database between 2016 and 2020 to identify adult hospitalizations with a diagnosis of anal cancer and to highlight epidemiological trends. Inpatient mortality, mean length of stay (LOS), mean total hospital charge (THC), type of insurance, and rates of treatments were estimated. Age groups were defined as young (18-45 years), middle (46-60 years), and elder ( > 60 years). Results: From 2016 to 2020, a total of 18,425 admissions were recorded for anal cancer. The data indicate a significant increase in the rates of hospitalizations with an average rise of 38 cases per year (p = 0.022). The lowest number of cases occurred in 2017 (2,700), while the peak was observed in 2019 (4,635). Specifically, the elderly age group showed an increased trend in anal cancer hospitalizations, and the middle-aged group showed a decreased trend. Mean age increased from 61.6 years in 2016 to 63.6 years in 2020 (p = 0.008). Female and white predominance remained constant over 5 years (58.1% and 70.4%, respectively). Inpatient mortality ranged from 1.5% in 2016 compared to 2.7% in 2020, with no statistically significant difference, however a trend towards increased mortality was observed in the young age group (p = 0.076). No significant changes in the prevalence of sexually transmitted diseases (7.7%) and inflammatory bowel disease (6.5%) were noted, including ulcerative colitis and Crohn’s disease. There was an increase in mean THC (p = 0.000) and LOS (p = 0.069) over 5 years. HIV diagnosis increased over time among young and middle-aged groups. The middle-aged group had a raising prevalence of hemorrhoids, perianal venous thrombosis, and substance abuse. While overall, we noted a decline in the usage of chemotherapy, radiation therapy, and anal excision, there was increasing trend for radiation therapy (P = 0.091) utilization in the elderly group. Conclusions: Anal cancer hospitalizations increased from 2016 to 2020, predominantly in the elderly age group with increasing utilization of radiation treatment in elderly. Increased rates of HIV infection could correlate with increased mortality noted in the younger patients. Despite mortality not significantly changing for overall population, there was a significantly higher THC and LOS over time. In light of the escalating admissions of anal cancer and the concurrent rise in asymptomatic HIV cases, further research is warranted to elucidate the underlying factors causing increased healthcare utilization despite stable mortality.