[Multiple primary malignant neoplasms in the national cancer center during 1962-1981].

Four hundred and eight cases with multiple primary malignant neoplasms from 5,456 autopsy cases were reviewed, and their age, sex, sites and relationship between the two cancers were analysed. Expected number of the second cancer was calculated based upon the person-years of 8,444 cases with primary gastro-intestinal cancers. Significant higher incidence was observed in the oropharyngeal cancer, esophageal cancer in male, and colon cancer in female. Organ relationship was present along the gastrointestinal tract, as observed in autopsy cases. Biological meaning of multiple primary malignant neoplasms was discussed.