Mortality from cancers of the digestive system among grand multiparous women in Taiwan.

The aim of this study is to evaluate the significance of grand multiparous (GM) status in the mortality from cancers of the digestive system among a cohort of GM women in Taiwan during the period 1978-2008. The study cohort consisted of 144,922 women with at least five children (GM women) in the Taiwan Birth Register between 1 January 1978 and 31 December 2003. Standardized mortality ratios (SMRs) for cancers of the digestive system including esophagus, stomach, colon, rectum, liver, and pancreas were calculated by dividing the numbers of observed cancer deaths to the expected numbers of deaths based on the rates of national female population. Among the 144,922 GM women, a total of 23, 220, 213, 92, 397, and 65 deaths were caused by cancers of the esophagus, stomach, colon, rectum, liver, and pancreas, respectively. The SMRs among GM women were 1.61 (95% confidence intervals (CI): 0.95-2.27) for esophageal cancer, 1.15 (95% CI: 1.00-1.31) for stomach cancer, 1.07 (95% CI: 0.93-1.22) for colon cancer, 0.94 (95% CI: 0.75-1.14) for rectal cancer, 1.18 (95% CI: 1.06-1.30) for liver cancer, and 0.79 (95% CI: 0.60-0.98) for pancreatic cancer. This study provides evidence that grand multiparity may confer a protective effect on the risk of death from pancreatic cancer. However, the results suggest that GM women may increase the risk of death from cancers of the liver and stomach.