Comparing the trend of colorectal cancer before and after the implementation of the Population-Based National Cancer Registry in Iran.

Abstract

Introduction: Colorectal cancer is the third most common malignancy and the second leading cause of cancer deaths worldwide. This disease is the fourth most common malignancy in Iran. Since knowing the trend of this cancer is necessary for planning; this study aimed to compare the trend of colorectal cancer before and after implementing the Population-Based National Cancer Registry.

Methods: In this time series analysis using secondary data, the autoregressive integrated moving average (ARIMA) was used to predict the future trend. An Interrupted Time Series (ITS) regression model was also used to compare the incidence and mortality of colorectal cancer before and after the setting up of the Iranian National Population-Based Cancer Registry (INPCR).

Results: Among Iranian men, an increasing trend in the incidence (from 16.8 in 2019 to 19.5 per 100,000 in 2027) and deaths of colorectal cancer for the coming years was predicted (from 10.2 in 2019 to 11.2 per 100,000 in 2027). A similar pattern was also observed for the incidence of this cancer among females (from 11 in 2019 to 12.3 per 100,000 in 2027), but a reverse pattern was predicted for the trend of deaths among women (from 2.06 in 2019 to 1.93 per 100,000 in 2027). During the years after the implementation of the INPCR, the trend of cases (β: 0.33, p < 0.001) as well as deaths due to colorectal cancer was significantly increasing (β: 0.08, p < 0.001) among the Iranian population.

Conclusions: Probably, part of the increase in the incidence and mortality of colorectal cancer could be due to the improvement of the registration and reporting system of new cancer cases.