Urban vs. rural: colorectal cancer survival and prognostic disparities from 2000 to 2019

Abstract

This study aimed to analyze the differences in colorectal cancer (CRC) survival between urban and rural areas over the past 20 years, as well as investigate potential prognostic factors for CRC survival in both populations. Using registry data from Surveillance, Epidemiology, and End Results (SEER) from 2000 to 2019, 463,827 CRC cases were identified, with 85.8% in urban and 14.2% in rural areas. The mortality of CRC surpassed its survival rate by the sixth year after diagnosis in urban areas and the fifth year in rural areas. Furthermore, the 5-year overall survival (OS) of CRC increased by 2.9-4.3 percentage points in urban and 0.6-1.5 percentage points in rural areas over the past two decades. Multivariable Cox regression models identified independent prognostic factors for OS and disease-specific survival (DSS) of CRC in urban and rural areas, including age over 40, Black ethnicity, and tumor size greater than 5 cm. In addition, household income below $75,000 was found to be an independent prognostic factor for OS and DSS of CRC in urban areas, while income below $55,000 was a significant factor for rural areas. In conclusion, this study found a notable difference in CRC survival between rural and urban areas. Independent prognostic factors shared among both rural and urban areas include age, tumor size, and race, while household income seem to be area-specific predictive variables. Collaboration between healthcare providers, patients, and communities to improve awareness and early detection of CRC may help to further advance survival rates.

Keywords: colorectal cancer; end results; epidemiology; prognostic; surveillance; survival; urban-rural.

Figure 1

Comparative OS of CRC: age, sex, race, and household income factors in urban and rural areas. (A,B) In urban and rural areas, CRC patients under the age of 40 have the worst OS. (C,D) The OS of male CRC patients in urban areas is worse than that of female patients, while there is no significant difference OS between male and female patients in rural areas. (E,F) Black CRC patients have the lowest OS in urban and rural areas. (G,H) CRC patients with incomes exceeding $75,000 in urban and rural households have the highest OS, while CRC patients with incomes below $35,000 have the lowest OS.

Figure 2

Comparative DSS of CRC: age, gender, ethnicity, and income factors in urban and rural areas. (A,B) Urban and rural CRC patients over 65 years old have the worst DSS. (C,D) The DSS of CRC women in urban and rural areas is lower than that of men. (E,F) The DSS of black people in urban and rural areas is the lowest. (G,H) CRC patients with households incomes below $35,000 in urban and rural have the lowest DSS.

Figure 3

Comparative OS of CRC: primary site, stage, tumor size, urban–rural and year of diagnosis. (A,B) The OS of CRC patients with primary site Rectum and Cecum and Appendix was the worst in urban, it is not significantly different compared the primary site in rural. (C,D) Whether in urban or rural, the OS of CRC patients in Stage IV and Stage Unknown were significantly reduced. (E,F) No matter in urban or rural, the OS of CRC patients with tumors over 5 cm was significantly reduced. (G) The OS of urban CRC patients is slightly lower than that of rural patients. (H) Comparison of OS in CRC patients diagnosed in urban and rural areas from 2000 to 2019.

Figure 4

Comparative DSS of CRC: Primary Site, Stage, Tumor Size, Urban–Rural and year of diagnosis. (A,B) The DSS of CRC patients with primary site Right colon and Cecum and Appendix was the worst in urban and rural. (C,D) No matter in urban or rural, the DSS of CRC patients in Stage IV and Stage Unknown were significantly reduced. (E,F) The DSS of CRC patients with tumors over 5 cm was significantly reduced. (G) There was no significant difference in DSS between urban and rural CRC patients. (H) Comparison of DSS in CRC patients diagnosed in urban and rural areas from 2000 to 2019.

Figure 5

Changes of CRC cases, survival and mortality in urban and rural areas in 20 years. (A) Number of CRC per year from 2000 to 2019, shows that the number of cancer diagnoses in rural and urban areas remained relatively stable from 2000 to 2017, and the number of cancer diagnoses increased significantly from 2018 to 2019. (B) The tumor mortality rate (49.7%) and survival rate (50.3%) reached a balance in the sixth year in urban. (C) The tumor mortality rate (49.6%) and survival rate (50.4%) reached a balance in the fifth year in rural. (D) Survival of CRC changes in 20 years at urban and rural areas. (E) Mortality of CRC changes in 20 years at urban and rural areas.

Figure 6

Comparison of 1-year, 3-year, 5-year, 10-year, 15-year, and 20-year OS of CRC between urban and rural in 20 years. (A) The change of CRC’s 1-year OS in metropolitan, medium city, small city, adjacent to a metropolitan and countryside, Compared with 20 years ago, the 1-year OS of CRC in urban and rural has significantly improved. (B) Compared with 15 years ago, the 3-year OS of CRC in urban and rural increased by 0.9–3.2 percentage points. (C) Compared with 15 years ago, the 5-year OS of CRC in urban and rural increased by 0.6–4.3 percentage points. (D) Compared with 2000, the 10-year OS of CRC in urban increased by 2.3–3.0 percentage points in 2010,in the adjacent to a metropolitan area, it increased by 5.4 percentage points, in the not adjacent to a metropolis area, it decreased by 1.9 percentage points. (E) Compared with 2000, the 15-year OS of CRC in urban and rural increased by 1.8–3.0 percentage points in 2005. (F) Comparison of 20-year OS of CRC in urban and rural.