Carcinoma of the colon and rectum--growth rate.

Twenty-seven carcinomas of the colon or rectum are presented which could retrospectively be measured on radiographs at two separate occasions. The mean diameter of the tumors at first and second investigations was 35 mm (10-90 mm) and 65 mm (30-110 mm), respectively, and the median interval between these examinations was 11 months (4-91 months). The median linear growth rate was 0.083 mm/day (0.008-0.262 mm/day). The median time for doubling of tumor volume was 130 days (53-1570 days), assuming a three-dimensional pattern of tumor growth. A significant correlation between poor differentiation and high linear growth rate (greater than or equal to 0.1 mm/day) was found. It is suggested that the high growth rate observed in this investigation in comparison with some previous studies may be due to the large size of the tumors and, hence, to their great risk of being malignant already at the first examination.