Does MRI Have a Role in the Preoperative Staging of Penile Cancer?

Background Penile cancer is a rare malignancy usually requiring surgery to achieve oncological control of the primary tumour but often at the expense of functional length. The presenting stage of the primary is a crucial factor in determining the most appropriate surgical procedure. Accurate preoperative staging is essential, and current modalities include clinical and radiological assessment. Clinical staging can, however, be hampered by patient body habitus and unreliable for more advanced T4 tumours, whereas radiological staging allows for more detailed identification of tissue planes and tumour involvement. There is no clear consensus on the preferred imaging technique, although, in the current European Association of Urology penile cancer guidelines, MRI is recommended with the use of ultrasound when MRI is not available. It was recommended that having the penis in an erect state by the administration of intra-cavernosal prostaglandin gave a more detailed picture enabling a greater predictor of corporal involvement. Recent studies have, however, suggested that there may be no such advantage. Methodology A retrospective review was conducted of all patients who underwent surgery for penile cancer comparing the preoperative MRI stage with the final pathological stage between July 2009 and June 2023. In addition to the MRI, patients were given an intra-cavernosal injection of prostaglandin E1 to induce tumescence unless otherwise indicated. All imaging was reported by a single consultant uro-radiologist with surgery undertaken by a single surgeon and pathology reviewed through the supra-regional penile multidisciplinary team. Results A total of 136 penile cancer patients were included in the review. Within this cohort, 98 patients had an MRI without intra-cavernosal prostaglandin and the number who had Ta, T1, T2, T3 and T4 histopathological stages was 3, 31, 45, 18, and 1, respectively. The preoperative MRI stage had a low agreement with the final histological stage for early tumours, with sensitivities and specificity of 35% and 97% for T1 and 56% and 80% for T2, respectively. Sensitivity and specificity increased for cavernosal involvement at 83% and 95%, respectively. In addition, a further 38 patients had an MRI in conjunction with an injection of prostaglandin E1 which failed to show any diagnostic improvement in sensitivity or specificity in the preoperative MRI stage. Conclusions The use of MRI as a preoperative modality for staging penile cancer performs best for identifying tumour involvement of the cavernosal bodies. Performing the MRI with the penis erect with the use of an intra-cavernosal injection did not offer any additional benefit in accurately staging penile cancer.