According to last National cancer registry reports, north and northwest areas of Iran had the highest incidence and mortality of GI cancers. Located in the northwest of Iran, East Azerbaijan is the largest and most populated province, and has a high incidence of gastrointestinal tract cancers, including stomach and colorectal cancers. Higher prevalence of some well-known risk factors including H. pylori infection, smoking, opium use, higher usage of biomass and so exposure to polycyclic aromatic hydrocarbons (PAH), and dietary factors may explain higher incidence of GI cancers in North/Northwest of Iran . Latest results of the East Azerbaijan Population-Based Cancer Registry program indicate that gastrointestinal cancers remain common, with significant increasing trends in their ASRs in East Azerbaijan.

During the 5 years of study (2015 to 2019) all cases with confirmed primary and newly diagnosed with cancer for each year were collected,recorded and registered. Well-trained health information technology staff (the EA-PBCR team) collected data from 20 counties, 62 cities, and 44 districts about newly diagnosed cancers. The registered data were all population-based and obtained from different sources included 33 pathology laboratories (including their pathology and cytology reports); the medical records from 20 educational and private hospitals, radiotherapy, and hematology centers; and 35 imaging centers. Data for cancer-related deaths were obtained from the causes of death registry of Tabriz University of Medical Sciences. Data collection was performed using active and passive methods. After completing data entry, quality control, consistency checks and basic analysis, manual quality controls and computerized validity checks of the cancer registry system were performed based on the IARC criteria, in the cancer registry office of East Azerbaijan province. This involved assessing factors which influence comparability, validity, timeliness, and completeness.

As the most common cancer incidence among males, stomach cancer had ASR of 28.83 in 2015 which decreased to 22.13 in 2019 (per 100,000 male). In 2015 the ASR of stomach cancer was 13.93 in female, which decreased to 11.49 (per 100,000 female). Colorectal cancer was the second most common cancer in both sexes, with an ASR of 17.51 in male and 14.15 in female during 2015 that decreased to 21.34 in male but increased to 17.08 in female in 2019. Esophageal cancer had an ASR of 4.65 in male and 7.36 in female in 2015 which was increased to 8.58 in male, but slightly decreased to 6.41 in female in 2019. Liver cancer with an ASR of 5.85 in male and 3.84 in female was another common cancer in 2015 , that the ASRs was obviously decreased to 1.96 in male and 1.02 in female in 2019.

Comparing with previous reported results in East Azerbaijan we faced with some different trends in ASRs of GI cancer in East Azerbaijan. While the incidences of stomach cancer was decreased in both sexes, colorectal cancer had an increased ASR in female. However liver cancer obviously decreased in both sexes, esophageal cancer incidence increased in male but decreased in female during 5 years of study.