[Analysis of tumor volume in latent prostatic carcinoma]

An assessment has been made of the histopathological characteristics of latent prostatic carcinoma and the tumor volume in 500 male Japanese patients who underwent dissection at The Jikei University since 1983. A microscopic observation was made of the prostatic glands extirpated totally at the necropsy, fixed with formalin and prepared as a step-section in a thickness of 3 mm. In the cases of latent carcinoma, after photographing the lesion in the same magnification and measuring the area of the carcinoma lesion with a digitizer, the volume was calculated by multiplying the thickness of 3 mm, and carcinoma volume was determined by integrating the value of each slice and adjusted by a conversion formula. The incidence of latent carcinoma was 104 cases out of 500 (22%). The incidence increased as the age layer becomes higher, and latent carcinoma was observed in 44% of the patients aged 80 and above. Complication of latent carcinoma with prostatic hyperplasia was presumed to be an independent phenomenon in so far as it is seen from the statistical aspect. The patients were classified histopathologically into well-differentiated type (64%), mixed type (27%) and poorly-differentiated type (9%), showing high incidence in the low-aged layer of well-differentiated lesions and in the high-aged layer of mixed type lesions and in the high-aged layer of mixed type lesions. The average tumor volume of latent carcinoma was so small as 231 mm3, but many of the lesions in the cases of well-differentiated type were small, being on average 103.9 mm3, but many of the lesions in the cases of poorly-differentiated type were large, being on average 642.2 mm3. Statistically, with a tumor size of 200 mm3 as the boundary, a difference was observed in the distribution of histological constitution between the group with smaller lesions and the group with larger lesions. As an application of this result to the clinical carcinoma of stage A, the value of volume of 200 mm3 was considered to be important as a diagnostic criterion in deciding the necessity of treatment.