Radiotherapy to the rare penile metastases of rectal adenocarcinoma: a case report

Abstract

Background: Malignant penile tumor is very rare, despite its nature is primary or secondary. Primary penile malignancy was reported with a very low incidence ranging from 0.58 to 1.3 cases per 100,000 people, and the incidence of secondary penile malignancy is much rarer, with no more than 500 cases reported yet.There are no standard treatment guidelines for secondary penile malignancy since its scarcity. Only sporadic cases showed palliative operation or radiotherapy as management. Surgery with penectomy remains the optimal choice with longest median survival time of 1 year; radiotherapy has an average survival of 8 months.Case Description: We reported a 69-year-old man with recurrent rectal adenocarcinoma, accompanied with lung, liver, and penile metastases. He suffered from penile tenderness, painful sensation, dysuria, and aggravated urine frequency due to his penile metastases, even under salvage chemotherapy and target therapy. Therefore, regional radiotherapy was applied to the penis, followed by apparent symptom relief.However, the time interval from the diagnosis of his penile metastases to his death was approximately 6 months, and the interval from the end of radiotherapy was 4 months. Among all the penile metastases reported before, one-third of the penile metastases were diagnosed in synchrony with the primary tumors, while the remaining two-thirds were noted within 18 months after the primary ones were diagnosed.Conclusions: When penile metastases were diagnosed, the majority of cases (90%) were found to have disseminated disease, with a survival time no longer than 12 months, which was associated with a very poor prognosis. For such patient, applying regional radiotherapy to the penis could play a palliative role for symptom relief, and might remain a better quality of life for the rest of the patient's life.