Epidemiological changes in colorectal cancer in Shiraz, Iran: 1980-2000

Background: The present study was performed to determine trends in colorectal cancer rates over the past two decades (1970-80 vs 1990-2000) with in a main referral centre in Shiraz, Iran. Methods: The Cancer Registry data on all colorectal cancer cases from 1970 to 2000 in Shiraz, Iran, were analysed. Demographic characteristics, clinical features, cancer site and type and stage of cancer were compared in the populations of two different decades. Results: The age-adjusted incidence of colorectal cancer per 100 000 population per year increased in men from a mean annual incidence of 1.61 in the decade 1970-80 to 4.2 in 1990-2000 (P < 0.05), and in women from 2.35 to 2.72 (P < 0.05). In 1970-80, patients over 60 years had 62.5% of all the colorectal cancers, which decreased to 30% in 1990-2000 (P < 0.05). The distribution of right and left sided cancers were almost equal and showed no significant difference between the two decades (P > 0.05). Conclusion: A marked increase in the incidence of colorectal cancer has been shown in Shiraz. Also, the marked increase in the incidence of colorectal cancer in the 40-60-year-old age group shown in the present study necessitates a more detailed work-up in younger age group patients.