GEOGRAPHIC ASSOCIATION BETWEEN URINARY-EXCRETION OF N-NITROSO COMPOUNDS AND ESOPHAGEAL CANCER MORTALITY IN CHINA

Overnight urine samples were collected from approximately 60 male adul ts in each of 69 counties of China in 1989. Two specimens were collect ed from each subject-one after a loading dose of proline and ascorbic acid and another after a loading dose of proline only. Levels of N-nit rosamino acids and nitrate were measured in urine samples and correlat ed with cumulative mortality rates for subjects aged between 0 and 64 years in the 1970s. Oesophageal cancer mortality rates were pcsitively and significantly associated with (i) urinary levels of excreted N-ni trosoproline (NPRO) (after proline and ascorbic acid loading or prolin e loading only), (ii) N-nitrososarcosine levels, and (iii) nitrosation potential (the decrease in the amount of urinary NPRO after adding as corbic acid to the proline load). There were also positive correlation s between the urinary level of NPRO or other N-nitrosamino acids and t hat of nitrate. The urinary excretion of nitrate was associated with c onsumption of various nitrate-rich vegetables. The results suggest tha t N-nitroso compounds (NOC) or other nitrite-derived carcinogens are i mplicated in the aetiology of oesophageal cancer in China. (C) 1993 Wi ley-Liss, Inc.