Optimal Timing of Total Gastrectomy to Prevent Diffuse Gastric Cancer in Individuals With Pathogenic Variants in CDH1

Carriers of pathogenic variants in CDH1 have a high risk of hereditary diffuse gastric cancer (HDGC). Guidelines recommend prophylactic total gastrectomy (PTG) at age 20-30 years, although there is controversy over the optimal age. We developed a simulation model to analyze the effects of PTG at different ages on quality-adjusted life-years (QALYs), cancer mortality, and life expectancy.

We used a Markov model of HDGC progression associated with pathogenic variants in CDH1 to simulate outcomes of hypothetical cohorts with different ages at time of PTG (ages 20-79 years). Model inputs including health state transition probabilities, mortality and complication rates, quality of life utility values, and endoscopic surveillance sensitivity were derived from publications. The primary outcome, used to determine the optimal strategy, was age at which PTG yielded the highest QALYs. Secondary outcomes were cancer mortality and unadjusted life-years.

Our model found that for men, the optimal age for PTG is 39 years, resulting in 32.01 incremental QALYs, 58.81 life-years (biologic age, 72.81 years), and lifetime cancer mortality of 8.5%. Incorporating endoscopic surveillance prior to PTG decreased cancer mortality to 6.7%, but had lower QALYs (31.59). PTG at age 30 reduced cancer mortality to 3.2%, with 31.45 incremental QALYs. For women, the optimal age for PTG was calculated to be 30 years, with 33.09 incremental QALYs, 66.17 life-years (biologic age, 80.17 years), and lifetime cancer mortality of 1.6%. Addition of endoscopic surveillance did not decrease the risk of HDGC mortality in women.

Using a Markov model of HDGC progression associated with pathogenic variants in CDH1 to simulate outcomes, we found the optimal ages for PTG to be 39 years for men and 30 years for women, when QALYs are the primary endpoint. These ages for PTG are older than those of current recommendations.