Trends of colorectal cancer in a central area of Iran during 2009–2014. An application of joinpoint regression

Introduction
Colorectal cancer (CRC) has become a major public health concern. We analysed current CRC statistics in Arak, including the estimated number of new cases among males and females, age standardized rates (ASRs), and trends for cases diagnosed in the period 2009–2014.

Material and methods
In this study, reported cases of CRC from 2009 through 2014 for Arak residents were obtained from the Arak cancer registry database. We used the direct method to calculate annual ASRs. Joinpoint regression was performed on the ASRs for the whole study period, and we calculated the annual percentage changes (APC).

Results
533 new CRC cases were included. The annual ASRs of CRC per 100,000 population during 2009–2014 were 13.58 (95% CI: 11.9–15.42), 16.52 (95% CI: 14.62–18.60), 15.00 (95% CI: 13.72–16.35) for females, males, and both genders, respectively. Females had an increasing trend in ASRs (APC: 10.25% and CI 95%: –0.79 to 22.53), and a slightly increasing trend was observed among males (APC = 5.03% and CI 95%: –6.14 to 17.53).

Conclusions
The increasing trend was higher among females than males. These findings raise considerable concern related to a crucial growing public health problem in Arak. They were higher than the averages of ASRs in all of Iran. Furthermore, any increase in the ASRs of CRC may be due to the promotion and improvement in the quality of the cancer registry over time. It is recommended that the quality of the cancer registry is promoted more than the former.