Incremental value of MRI for preoperative penile cancer staging

To evaluate the incremental value of magnetic resonance imaging (MRI), compared to clinical examination, for penile cancer (PC) local staging.

Twenty-five consecutive patients with histologically proven PC were evaluated prospectively. MRI staging was performed on 1.5 and 3.0T scanners using high-resolution T₂ -weighted and postcontrast T₁ -weighted images. Two blinded observers interpreted MR images. Clinical local staging was performed by experienced urologists. The pathology report was used as the standard of reference.

The interobserver agreement for MRI staging, using a kappa test for T-staging was moderate, 0.52 (95% confidence interval [CI] = 0.24-0.78), P = 0.001, although a high correlation for N-staging, 0.72 (95% CI = 0.42-1.00), P = 0.001, was detected. Clinical staging was correct in 52.0% (13/25) of patients. After pathological staging, five (20.0%) lesions were upstaged and seven (28.0%) lesions were downstaged compared to clinical examination. MRI accurately defined T-staging in 18/25 lesions (72.0%). After pathologic staging, five (20.0%) were upstaged and two downstaged (8.0%), compared to MRI. Fifteen patients were submitted to inguinal and pelvic lymphadenectomy and considered for comparison of accuracy of nodal staging by physical examination and MRI. Clinical staging accurately staged 7/15 patients (46.7%). After histopathologic analysis, six cases had nodal staging upgraded and two cases were downgraded. MRI correctly staged 13/15 (86.7%). Using a chi-square for comparison, differences in proportion of corrected staging between clinical examination and MRI were not significant for T-staging (P = 0.14), but were significant for nodal staging (P = 0.02).

According to our results, MRI improves local staging of PC patients, particularly for those with limited physical examination.

1 J. Magn. Reson. Imaging 2017;45:118-124.