Trends in the Characteristics, Treatment, and Outcomes of Rectal Adenocarcinoma in the US From 2004 to 2019

Abstract

Rectal cancer management has significantly evolved over the last 2 decades. This study aimed to evaluate trends in the characteristics, treatment, and outcomes of rectal adenocarcinoma across 16 years. This retrospective, observational case series study used data from the National Cancer Database (NCDB) to evaluate patients diagnosed with rectal adenocarcinoma from 2004 through 2019. Data analysis was performed from March to May 2022. Trends in the treatment and outcomes of rectal adenocarcinoma in the US between 2004 and 2019 were explored. This period was subdivided into 4 equal periods: 2004-2007, 2008-2011, 2012-2015, and 2016-2019. Patient and tumor characteristics, treatments, short-term outcomes, and overall survival. A total of 318 548 patients diagnosed with rectal adenocarcinoma were included in the analysis, 191 369 (60.1%) of whom were males and 127 179 (39.9%%) were females. The mean (SD) age of the patients was 63.5 (13.4) years, and 46 824 patients (14.8%) were younger than 50 years. Among the patients, 10 859 (3.4%) were of Asian race and ethnicity, 28 464 (8.9%) were Black, and 271 236 (85.1%) were White. The percentage of patients younger than 50 years who were diagnosed with rectal cancer increased by 1.5%, from 13.9% in period 1 to 15.4% in period 4. Patients in the last period (2016-2019) presented more often with stages III (36.2% vs 30.2% vs 25.0% vs 23.4%; P < .001) and IV (21.5% vs 19.3% vs 18.1% vs 18.6%; P < .001) disease compared with those in the remaining 3 periods. The use of chemotherapy (36.8% vs 48.1% vs 49.1% vs 47.0%; P < .001) and immunotherapy (0.4% vs 0.2% vs 3.5% vs 6.5%; P < .001) significantly increased across the 4 periods. Although neoadjuvant radiotherapy was used more often across the periods studied (28.6% in period 1 to 34.3% in period 4), the use of adjuvant radiotherapy was reduced by half (12.9% to 6.0%). The median (IQR) time from diagnosis to definitive surgery increased from 95 (15-126) days in period 1 to 128 (47-158) days in period 4. The rate of use of open surgery decreased by half (60.1% in period 2 to 30.1% in period 4), and the use of robotic surgery significantly increased (5.2% in period 2 to 28.4% in period 4). The conversion rate was significantly reduced (11.2% in period 2 to 7.3% in period 4) and the median (IQR) hospital stay decreased by 2 days, from 6 (3-9) days to 4 (2-7) days. The median (IQR) overall survival significantly increased across the periods (from 83.1 months [95% CI, 81.8-84.6 months] in period 1 to 92.1 months [95% CI, 90.2-93.6 months] in period 3; P < .001). The findings of this case series study suggest a treatment trend of increased use of chemotherapy, immunotherapy, sphincter-saving surgery, and minimally invasive surgery. In addition, the time between diagnosis and definitive surgery increased by a median of 33 days. This treatment trend was associated with a significant improvement in the overall survival, reduction in the conversion rate by 3.9%, and a 2-day shorter hospital stay. These findings have major clinical relevance to the management of rectal cancer. The improvements seen in short-term outcomes and survival of patients diagnosed with rectal cancer can probably be attributed to the treatment trends observed. Continued improvement in outcomes warrant further updates in treatments.