The possibility of ‘de novo’ cancer in the prostate

  Background:  To investigate the possibility of ‘de novo’ prostate cancer by analyzing the relationship between high grade prostatic intraepithelial neoplasia (HGPIN) and latent prostate cancer. Materials and methods:  Latent prostate cancers found at autopsy were examined and 55 cancer foci with a poorly (Gleason grade 4 and 5) or moderately (Gleason grade 3) differentiated component were selected. The 55 foci were separated into two groups: (i) foci with either a poorly or moderately differentiated component only (single differentiation group, SDG); and (ii) mixed foci with two or more types of differentiation components (mixed differentiation group, MDG). High grade intraepithelial neoplasia was defined as positive if it was observed within 2 mm from the edge of the cancer focus and the relationship between HGPIN and the two groups was investigated. Results:  The MDG had 39 cancer foci (71.0%) and there were 16 in the SDG (29.0%). There were 31 foci that were small‐volume cancers (<0.2 mL). In the MDG, 13 small‐volume cancer foci were HGPIN positive, but in the SDG, none of the small‐volume cancers were HGPIN positive. Conclusions:  Small‐volume cancer foci without HGPIN in the SDG may be candidates for de novo prostate cancers.