Multiple primary malignant neoplasms. The Connecticut experience, 1935-1964.

Results for non-simultaneously diagnosed malignant tumors from Connecticut indicate that individuals with one malignant neoplasm have 1.29 times the risk of developing a new independent primary tumor when compared to individuals who never had cancer (P less than 0.01). However, the increased risk of multiple primary tumors is highly selective on a site-specific basis. Table 135 presents Connecticut Registry data indicating the risk of a subsequent primary malignancy by anatomic site of the later primary in patients with a first primary cancer. Tables 136 and 137 present tabulations for anatomic sites with statistically significant excesses and deficiencies, with an analysis by time interval between the two malignancies. Finally, Table 138 presents figures showing histologic confirmation for site-group paris with significant excesses of observed-over-expected later primary malignant neoplasms. The reader should bear in mind that just as the risk of subsequent primaries varies with the anatomic site of the subsequent primary (Table 135), the risk is also highly dependent upon the anatomic site of the first primary cancer (Chapters 6-12).