The prognostic value of digital rectal exam for the existence of advanced pathologic features after prostatectomy

Accurate staging at the time of prostate cancer diagnosis is fundamental to risk stratification and management counseling. Digital rectal exam (DRE) is foundational in clinical staging of prostate cancer, even with a known limited interexaminer agreement and poor sensitivity for detecting extraprostatic disease. We sought to evaluate the prognostic value of DRE for the presence of advanced pathologic features (APFs) following radical prostatectomy (RP).

All patients undergoing RP as primary treatment for clinically localized prostate cancer in the National Cancer Database between 2008 and 2014 were identified. Patients with additional malignancies, prior treatment with radiation or systemic therapy, incongruent clinical staging and DRE findings or without fully evaluable clinical staging were excluded. The primary outcome was the presence of postsurgical APFs, defined as positive surgical margins, nodal disease, or pathologic stage T3 or greater. Multivariable logistic regression analysis was performed to account for prostate-specific antigen (PSA), biopsy grade group, percent of positive biopsy cores, and clinical stage.

In total, 91,525 patients consisting of 69,182 cT1, 20,641 cT2, and 1702 cT3-T4 were included. The average age was 61.1 ± 7.0 years, and the average PSA was 8.6 ± 10.3 ng/ml. On multivariable analysis, cT3 and T4 were associated with the presence of APFs (odds ratio [OR] 11.12, p < .01 and 5.28, p = .04), however, cT2 was only slightly associated with the presence of APFs when compared with cT1 (OR 1.15, p < .01). Furthermore, cT2 was associated with more node-positive disease (OR 1.63, p < .01), positive margins (OR 1.06, p < .01), and more than or equal to pT3 disease (OR 1.22, p < .01).

Overall, advanced clinical stage as assessed by DRE was independently associated with an increasing risk of APFs. For individual APFs, the greatest effect is noticed between clinical stage and nodal positivity and less so between clinical stage and positive margins. DRE continues to hold value, particularly for patients with locally advanced disease and potential lymph node disease.