Resection Of A Retroperitoneal Cancer Of Unknown Primary Site After Chemoradiation Therapy: A Case Report

Abstract

Background: Complete recovery from retroperitoneal squamous cell carcinoma of unknown primary site treated by multidisciplinary therapy is extremely rare.Case presentation: A 78-year-old man was referred to our hospital due to a mass measuring 8 cm in size in the left pelvic retroperitoneal area, which was diagnosed as a cancer of unknown primary site. The pathological type was squamous cell carcinoma. The left iliac artery/vein and ureter were involved in the tumor, and the tumor caused severe left leg pain. Although inflammation and symptoms were severe, palliative radiotherapy was considered. After that, biweekly combined therapy with docetaxel, cisplatin, and fluorouracil was planned. After 5 courses of chemotherapy, the tumor diameter reduced from 11.6 cm to 4 cm in size. In addition, the border between the iliac vessels, urinary tract and tumor became apparent. The patient underwent radical resection of the tumor 8 months after the treatment started. The left ureter and the external/internal iliac artery were preserved, but the external iliac vein was sacrificed because of the possibility of tumor invasion. The postoperative course was free of complications, and the patient was discharged 10 days after the operation. The histopathological findings showed no residual viable tumor cells or foreign body-type giant cells with necrosis. The pathological effect of chemotherapy was defined as Grade 3 (pathological complete response). The patient has experienced no recurrence or distant metastasis for 4 years.Conclusions: Multidisciplinary therapy succeeded in treating a retroperitoneal squamous cell carcinoma of unknown primary site with preservation of organ function.