A case of pathological complete response with neoadjuvant mFOLFOX6 chemotherapy for advanced lower rectal cancer

: A 69-year-old man diagnosed with lower rectal cancer was referred to our hospital. Rectal examination and colonoscopy showed a type 2 circular tumor, 2.5 cm from the anal verge. Biopsy led to a diagnosis of moderately differentiated adenocarcinoma. Computed tomography (CT) and magnetic resonance imaging (MRI) showed signs of invasion to the surrounding organs and metastasis to the mesorectal fascia and left obturator lymph node (cAI, cN3). Therefore, we decided to start neoadjuvant chemotherapy with leucovorin calcium( folinic acid), fluorouracil, and oxaliplatin( mFOLFOX6). The patient received six courses of chemotherapy. CT and MRI after chemotherapy showed a reduction in tumor size. Six weeks after chemotherapy, the patient underwent intersphincteric resection with ileostomy. Pathological examination demonstrated no residual cancer cells in the primary lesion or lymph node (Grade III, pathological complete response [pCR]). This study demonstrates that neoadjuvant chemotherapy can be a promising option for locally advanced rectal cancer.