Trends in net survival for patients with stomach cancer in Japan, 2000-14 (CONCORD-3)

We estimated net survival trends for patients with stomach cancer registered in 16 regional population-based cancer registries in Japan that participated in the CONCORD-3 study.

We included data on adults (15-99 years) diagnosed with stomach cancer between 2000 and 2014 and followed-up for their vital status until 31 December 2014. We grouped cancer patients into three anatomic groups (proximal, distal, and overlapping regions and stomach cancer, not otherwise specified) with the International Classification of Disease for Oncology, Third edition topography codes. We estimated 5-year net survival with the Pohar Perme estimator for three calendar periods (2000-2004, 2005-2009, 2010-2014), by age group (15-44, 45-54, 55-64, 65-74, and 75-99 years), anatomic group, and stage at diagnosis. All-ages survival estimates were age-standardized using the International Cancer Survival Standard weights.

Five-year net survival improved over time, from 50.5% in 2000-2004 to 57.6% and 60.3% in 2005-2009 and 2010-2014, respectively. Survival for patients with proximal stomach cancer improved from 49.7% in 2000-2004 to 53.5% 2005-2009 and plateaued to 53.1% in 2010-2014. Survival for distal stomach cancer increased from 64.8% in 2000-2004 to 67.6% and 68.2% in 2005-2009 and 2010-2014, respectively. In 2010-2014, 5-year net survival for patients with localized disease (94.8%) was much higher than survival for regional (53.7%) and distant (6.4%) disease.

Five-year net survival for stomach cancer improved noticeably during 2000-2014. This improvement might be due to advances in systemic chemotherapy. Although survival in distal stomach cancer had improved, no such improvement was seen in proximal stomach cancer. Standardizing esophagogastric junction cancer treatment may improve its outcomes and contribute to better survival in proximal stomach cancer overall. Scientific evaluation of screening programs is also needed to enhance the efficacy of stomach cancer control initiatives in Japan.