Tumour angiogenesis in latent prostatic carcinoma.

Unrestrained growth of various malignant tumours has been shown to depend upon a critical number of tumour cells which have switched to the angiogenic phenotype. Angiogenic phenotypes were noted in the early stage of prostatic carcinoma (PCa). We investigated 65 cases of latent PCa to define the correlation between tumour angiogenesis and tumour volume. Tumour angiogenesis was determined by the blood capillary density ratio (BCDR) evaluated by a colour image analysis system. Using experimental regression analysis, the correlation between the BCDR and PCa volume was divisible into two distinct stages. When the PCa showed a volume of more than 83 mm3, there was a significant positive correlation between the BCDR and PCa volume (rS-test P < 0.001). However, when the PCa showed a volume of less than 83 mm3, the BCDR remained at a low level which did not change until larger volumes were present (rS-test, NS; ANOVA, NS). The present study suggested that latent PCa showing a volume of less than 83 mm3 would be 'early' indolent carcinoma which, on undergoing additional events concerning tumour angiogenesis, would assume more aggressive growth.