en Oncology Oncology Original Article Original Article <span style="font-size:12px;"><span style="font-family:times new roman;"><span style="color:#0000FF;"><strong><em>Background</em></strong><strong>:</strong></span> Identifyng the incidence of cancer helps in planning and prioritizing resources for its screening, prevention, treatment and diagnosis. This study aimed at investigating a 25-year trend in gastrointestinal cancer in Northern Iran in the time span of 1991-2016.<br> <span style="color:#0000FF;"><strong><em>Methods:</em></strong></span> This research was a trend analysis. Study population was one thousand five hundred and thirty-five cancer patients referring to Shahid Rajai Hospital in Babolsar, northern Iran, as the only center for radiotherapy in the North of Iran, during 1991-2016.<br> <span style="color:#0000FF;"><strong><em>Results:</em></strong> </span>The highest incidence of stomach cancer was 111 (35%) in 2011 and the lowest incidence was 44 (16.3%) in 1996, The highest frequency of esophageal cancer was reported 137(56.1%) cases in 1991 and the lowest frequency was 78 (26.3%) cases in 2016, while the highest incidence of colorectal cancer was 109 (36.7%) cases in 2016 and its lowest frequency was 32 (16.3%) in 1996. There was also a significant difference in the frequency of gastrointestinal cancers in different studied years (p <.001).<br> <span style="color:#0000FF;"><strong><em>Conclusions</em></strong><strong>:</strong></span> The trends in the incidence of stomach and colorectal cancers in northern Iran were increasing and esophageal cancer was decreasing.</span></span><br> &nbsp; Colorectal Cancer, Esophageal Cancer, Gastrointestinal Cancer, Incidence 396 401 http://caspjim.com/browse.php?a_code=A-10-1369-1&slc_lang=en&sid=1 Hakimeh Mehdizadeh h.mhdizadeh@yahoo.com 100319475328460019200 100319475328460019200 No Babol University of Medical Sciences, Babol, Iran Ghahraman Mahmoudi Ghahraman48@yahoo.com 100319475328460019201 100319475328460019201 No Hospital administration Research Center, Sari Branch, Islamic Azad University, Sari, I R Iran Dariush Moslemi moslemi_d@yahoo.com 100319475328460019202 100319475328460019202 No Department of Radiation Oncology, Babol University of Medical Sciences, Babol, Iran Ali Bijani Alibijani@yahoo.com 100319475328460019203 100319475328460019203 No Social Determinants of Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran Mohammad Ali Jahani drmajahani@yahoo.com 100319475328460019204 100319475328460019204 Yes Social Determinants of Health Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran