Limited Adenocarcinoma of the Prostate on Needle Core Biopsy

Context.— Grading small foci of prostate cancer on a needle biopsy is often difficult, yet the clinical significance of accurate grading remains uncertain. Objective.— To assess if grading of limited adenocarcinoma on prostate biopsy specimen is critical. Design.— We studied 295 consecutive patients undergoing extended-sextant biopsy with only 1-core involvement of adenocarcinoma, followed by radical prostatectomy. Results.— The linear tumor lengths on these biopsy specimens were: less than 1 mm (n = 114); 1 mm or more or less than 2 mm (n = 82); 2 mm or more or less than 3 mm (n = 35); and 3 mm or more (n = 64). Longer length was strongly associated with higher Grade Group (GG) on biopsy or prostatectomy specimen, higher risk of extraprostatic extension/seminal vesicle invasion and positive surgical margin, and larger estimated tumor volume. When cases were compared based on biopsy specimen GG, higher grade was strongly associated with higher prostatectomy specimen GG, higher incidence of pT3/pT3b disease, and larger tumor volume. Outcome analysis further showed significantly higher risks for biochemical recurrence after radical prostatectomy in patients with 1 mm or more, 2 mm or more, 3 mm or more, GG2-4, GG3-4, GG4, less than 1 mm/GG2-4, less than 1 mm/GG3-4, less than 2 mm/GG3-4, 3 mm or more/GG2-4, or 3 mm or more/GG3-4 tumor on biopsy specimens, compared with respective control subgroups. In particular, 3 mm or more, GG3, and GG4 on biopsy specimens showed significance as independent prognosticators by multivariate analysis. Meanwhile, there were no significant differences in the rate of upgrading or downgrading after radical prostatectomy among those subgrouped by biopsy specimen tumor length (eg, <1 mm [44.7%] versus ≥1/<2 mm [41.5%] versus ≥2/<3 mm [45.7%] versus ≥3 mm [46.9%]). Conclusions.— These results indicate that pathologists still need to make maximum efforts to grade relatively small prostate cancer on biopsy specimens.