[1429] Increased Incidence of Primary Extranodal Gastrointestinal Non-Hodgkin Lymphomas Results Mainly from Diffuse Large B-Cell Lymphoma

Jenika M Howell, Iwona Auer-Grzesiak, James Zhang, Stefan J Urbanski. University of Calgary, Calgary, AB, Canada

Background: Primary extranodal Non-Hodgkin lymphomas of the gastrointestinal tract (GI NHL) have been on the rise. Recent Canadian data has shown increasing incidence of primary GI NHL, with high grade (Diffuse Large B-cell Lymphoma, DLBCL) histology to be among the most common diagnoses for all locations along the gastrointestinal tract. We assessed the demographic characteristics of patients diagnosed with primary GI NHL of DLBCL histology, as well as the incidence of primary GI NHL by histologic type over a 10-year period.
Design: The Calgary Health Region (now part of Alberta Health Services) includes the city of Calgary, with a population of over 1 million, as well as several other surrounding communities with a total population of 1,285 972 in 2008. All diagnoses of GI NHL made between January 1999 – January 2009 were reviewed using a regional pathology database. Patients 18 years and older living within health region boundaries were included.
Results: 149 confirmed cases of primary GI NHL were identified during the study period (January 1999-January 2009). Of these, 70 cases (47%) were found to correspond to high grade (DLBCL) histology, with a M:F ratio of 1.6:1. Distribution of DLBCL histology along the GI tract included stomach (54%=38/70), small bowel (38%=15/39), colon (50%=13/26), multiple GI sites (31%=4/13) and esophagus (0%=0/1). Yearly age- and gender-adjusted incidence rates by histologic type were found to be highest for DLBCL, followed by Marginal/MALT and Follicular lymphoma.
Conclusions: Nearly half of all identified cases of GI NHL showed high grade (DLBCL) histology at diagnosis. Reasons for this remain unclear. GI NHL subtype distribution has been shown to differ based on the population under study, which suggests various etiologic factors may be implicated. Since the increase in incidence affects all sites along the GI tract, factors other than H. pylori are responsible for this phenomenon. Concurrent inflammatory bowel disease, viral infections and genetic alterations to tissue [i.e. t(11; 18)] have been proposed. Environmental factors may operate as well. Further work is required to correlate cases with these potential risk factors.
Category: Hematopathology

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 206, Tuesday Afternoon


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