Mucinous adenocarcinoma of prostate and prostatic adenocarcinoma with mucinous components: a clinicopathological analysis of 143 cases.

AIM: The clinical significance of mucinous prostatic adenocarcinoma (PCa) remains uncertain. METHODS: From 6440 cases of PCa treated by radical prostatectomy from 2009 to 2014, mucinous components of 5-100% were found in 143 (2.2%) cases. RESULTS: The mean age was 61.4 years, mean pre-operative serum prostate-specific antigen (PSA) was 7.8 ng/ml and clinical stage category was cT1 in 81% and cT2 in 19% of cases. Cases were graded using the 2014 International Society of Urological Pathology recommendation of grading underlying architecture, and Gleason scores (GS) were 3 + 4 in 13.3%, 4 + 3 in 54.5%, 4 + 4 in 2.1%, 3 + 4 or 4 + 3 with tertiary 5 in 11.9% and 9-10 in 18.2%. The mucinous component invariably had a high-grade component. Extraprostatic extension was found in 46.8% of cases. In 21.6%, tumour volume was ≥3 cm³ and 9.7% had surgical margin positivity. Seminal vesicle involvement was found in 6.9%. In 73 cases the mucinous component was >25%, and when cases were divided on the basis of the area of mucin present (≤25 versus >25%) there was no significant difference between clinical or pathological features. Similar findings were achieved when cases were compared with grade-matched non-mucinous carcinoma controls. The 5-year biochemical recurrence rates for mucinous versus non-mucinous cancer were 12.5 versus 17% (P = 0.15). CONCLUSION: PCa with mucinous components is often high grade; however, the prognosis appears to be similar to non-mucinous cancers of similar GS.