CHARACTERISTICS IN PRIMARY SIGNET-RING CELL-CARCINOMA OF THE COLORECTUM, FROM CLINICOPATHOLOGICAL OBSERVATIONS

Background: The biological behavior of signet-ring cell carcinomas in colorectum tends to be worse than that of mucinous carcinomas. However , in previous studies, clinicopathological features of this disease ha ve been somewhat ill-defined because various histological criteria of this disease were adopted. Methods: We selected 11 cases of signet-rin g cell carcinomas and 29 cases of mucinous carcinomas among 1595 conse cutive colorectal carcinomas on defined criteria and compared clinicop athological and molecular biological features between these two types of carcinomas. Results: Clinical stagings of signet-ring cell carcinom as were far advanced and their prognosis tended to be worse than that of mucinous carcinomas. Furthermore, the incidence of K-ras mutations in signet-ring cell and mucinous carcinomas showed no difference betwe en these two types of carcinomas. However, the incidence of K-ras muta tion in these diseases was slightly lower than that in 30 ordinary col orectal carcinomas examined as a comparison. Conclusions: These result s suggest that the carcinogenesis of signet-ring cell and mucinous car cinomas are different from that of ordinary colorectal carcinomas and that there may exist other genes related to malignancy of signet-ring cell carcinomas.