Symptom palliation with QUAD Shot radiation therapy to penile metastasis derived from descending colon cancer: a case report

A 54-year-old man was diagnosed with descending colon cancer with metastases in the liver, para-aortic lymph nodes, and penis, and chemotherapy was introduced after construction of a colostomy. The patient reported only mild penile pain at the time of diagnosis; however, the pain gradually worsened and interfered with his daily life. Opioids did not provide sufficient analgesia, and the patient developed dysuria and priapism. Through construction of a cystostomy, palliative radiotherapy with QUAD Shot regimen (14 Gy in 4 fractions twice-daily on 2 days repeated every 4 weeks) to the penile metastasis was started for pain relief and tumor shrinkage. The radiation rapidly improved the penile symptoms, enabling opioid reduction and cystostomy removal. The patient remained pain-free and able to urinate on his own until his death. Metastatic penile tumors are rare, especially those derived from colon cancer. Penile metastases occur mainly in the late stages of cancer and may impair the patient's quality of life. In such cases, palliative radiotherapy, especially with QUAD Shot regimen, is useful with short treatment time, durable symptom control, and little adverse effect, maintaining quality of life.