Infiltrating ductal carcinoma (IDC) is a rare histologic subtype of prostate cancer. We investigated the clinicopathological features and prognosis of IDC compared with acinar cell carcinoma (ACC). We identified 3814 men diagnosed with prostate cancer between 2004 to and 2013 in the Surveillance, Epidemiology, and End Results database, including 511 IDC and 3303 ACC cases. Prostate cancer-specific survival (PCSS) was compared using univariate and multivariate Cox proportional hazards models. Generally, IDC occurred in older men (≥ 65 years old) and presented with larger sizes, and higher grades, American Joint Committee on Cancer (AJCC) stages, AJCC T stages, lymph node positive rates and metastasis rates. Men with IDC were less likely to undergo radical prostatectomy, but more likely to be treated with adjuvant radiation than men with ACC. Five-year PCSS rates were significantly worse in IDC. In the multivariate analysis, patients with ACC had a better PCSS than patients with IDC. In conclusion, IDC has unique clinicopathological characteristics and has worse prognosis than ACC. Multivariable Cox regression analysis showed that age over 85 years, higher grade and T stage, and metastasis at diagnosis were independent prognostic factors of worse survival outcomes, whereas radical prostatectomy was an independent prognostic factor of better survival outcomes.
Keywords: PCa; SEER; acinar cell carcinoma; infiltrating ductal carcinoma.