Curative Resection of Advanced Rectal Cancer with Direct Invasion of the Prostate and Extra-Regional Lymph Node Metastases after Chemotherapy

A-69-year-old man presented with an obstructed defecation. He was diagnosed as having advanced lower rectal cancer with direct invasion of the prostate and metastases to regional and para-aortic lymph nodes. Biopsy examination of the tumor showed RAS wild-type expression and negative BRAF V600E mutation. The patient received 13 courses of mFOLFOX6 and panitumumab(Pmab)in combination and 1 course of mFOLFOX6 alone. After the chemotherapy, the size of the primary tumor and lymph node metastases decreased remarkably. 18F-fluorodeoxyglucose-positron emission tomography(18F-FDG- PET)showed no 18F-FDG accumulation in the tumor and lymph nodes. We performed laparoscopic abdominoperineal resection with D3LD2 lymph node dissection and left external iliac lymph node(293-lt)sampling. Pathological examination revealed no residual cancer at the primary tumor location and only a few malignant cells remained in the 293-lt lymph node. The patient has shown no recurrence for 1 year without adjuvant chemotherapy. We conclude that mFOLFOX6 and Pmab in combination is an effective preoperative chemotherapy against advanced RAS wild-type rectal cancer. This strategy may reduce surgical invasion and save the surrounding organs while maintaining curability.