PURPOSE

Intraductal carcinoma of the prostate (IDC-P) is a relatively unstudied feature present in some prostate cancer (PC) diagnoses with several studies suggesting associations with higher Gleason scores (GS) and earlier time to biochemical recurrence (BCR) after definitive treatment. We looked to identify cases of IDC-P in the Veterans Health Administration (VHA) database and measure associations between IDC-P and pathological stage, BCR, and metastases.

METHODS

Patients in the VHA database diagnosed with PC from 2000 to 2017, treated with radical prostatectomy (RP) at the VHA were included in the cohort. BCR was defined as post-RP PSA >0.2 or administration of androgen deprivation therapy (ADT). Time to event was defined as time from RP to event or censor. Differences in cumulative incidences were assessed through Gray's test. Associations with IDC-P and pathologic features at RP, BCR and metastases were assessed through multivariable logistic and Cox regression models.

RESULTS

Of 13,913 patients meeting inclusion criteria, 45 patients had IDC-P. Median follow up was 8.8 years from RP. Multivariable logistic regressions showed patients with IDC-P were more likely to have GS ≥8 (Odds Ratio (OR) 1.14, P = .009) and higher T stages (T3 or 4 vs. T1 or 2 OR 1.14, P < .001). In total, 4,318 patients experienced a BCR, and 1,252 patients developed metastases of whom 26 and 12, respectively, had IDC-P. On multivariable regression IDC-P was associated with higher risk of BCR (IDC-P Hazard Ratio (HR) 1.71, P = .006) and metastases (HR 2.84, P < .001). Cumulative incidence of metastases at 4 years for IDC-P and non-IDC-P were 15.9% and 5.5% (P < .001) respectively.

CONCLUSIONS

In this analysis, IDC-P was associated with higher Gleason score at RP, shorter time to BCR, and higher rates of metastases. Further studies are warranted to investigate the molecular underpinnings of IDC-P to better guide treatment strategies for this aggressive disease entity.