Introduction: Colorectal cancer (CRC) is one of the most frequent tumors in Western countries. In Spain, widely different rates have been reported for distinct regions.
Aim: To determine the epidemiological characteristics of CRC in the province of Zamora in 1996 and 2003 and to identify possible variations in these characteristics in each of these two years.
Material and methods: We performed a descriptive, retrospective study of all cases of CRC diagnosed in the Complejo Asistencial de Zamora in 1996 and 2003.
Results: In 1996, 146 patients were diagnosed with CRC, representing an unadjusted and adjusted incidence of 70.85 and 49.40 cases per 10(5) inhabitants. In 2003, 173 patients were diagnosed, representing an unadjusted and adjusted incidence of 86.89 and 58.12 cases per 105 inhabitants. The mean age at diagnosis was 72.08 years in 1996 and 71.15 years in 2003. The mean time to diagnosis was 3.37 months in 1996 and 4.11 in 2003. The mean time to diagnosis in 1996 was 4.35 months in rectal tumors and 2.87 months in colon tumors (p = 0.013). In 2003, the mean time to diagnosis was 4.70 months in rectal tumors and 3.84 months in colon tumors (p = 0.0749). The mean time to diagnosis was 3.56 and 3.83 months in patients living in urban areas and was 3.24 and 4.35 months in those living in rural areas in 1996 and 2003, respectively. More than 65% of the neoplasms were located in the rectum and sigmoid colon, with no differences between the two years. In 1996, 46.1% of the tumors were stage III or IV at diagnosis while in 2003, this percentage increased to 50.9%. In both years, the four basic health areas with the highest rates within the province were Aliste, Carbajales, Carballeda and Corrales.
Conclusion: CRC is a highly frequent disease in the province of Zamora, especially in some of the western regions. The incidence of CRC was higher in 2003 than in 1996. Most of the tumors were located in the rectum and sigmoid colon. The time from symptom onset to diagnosis was prolonged. A high percentage of tumors were diagnosed in advanced stages.