Trends in diffuse type of gastric cancer: focus on younger women.

Background: Gastric cancer (GC) incidence has been decreasing over the last decades; however, there are uncertainties in trends and proportional distribution of the diffuse type.

Methods: GC incidence data were extracted from the population-based Friuli Venezia Giulia Cancer Registry. GC types (diffuse vs. others) were compared in relation to age at diagnosis, calendar years, and sexes.

Results: Between 1995 and 2021, diffuse GC accounted for 10.2% of all GCs. The proportion was greater among individuals aged <45 years, 34.0% in women and 25.7% in men. An increasing proportion over time was observed, in particular in women (from 9.9% in 1995-2000 to 14.10% during 2011-2021). In the last decade (2011-2021), a decreased incidence of all GC was observed, reaching an age-standardized rate (world standard) of 1.4/100,000 for men and 1.2/100,000 for women. Rates of diffuse GC were 0.3/100,000 in younger population.

Conclusion: Although the overall GC incidence is decreasing, the percentage of diffuse GC is increasing in the younger population, particularly in women. Reasons for the increased proportion of diffuse-type GC within younger women remain uncertain, possibly related to the decreased exposure to risk factors for other GC histotypes.