A 52-year-old man was diagnosed of stage 3 sigmoid colon cancer in December 2007. He was incidentally found to have iron deficiency anemia on preoperative evaluation for gluteal abscess. Colonoscopy revealed a polypoid mass at sigmoid colon. He underwent sigmoidectomy which pathology report demonstrated moderately differentiated adenocarcinoma invading into subserosa with 7 positive lymph nodes (pT3N2bM0). All surgical resected margins were free. He received 6-cycle of adjuvant bolus 5FU/leucovorin. He was doing well with normalized serum CEA postoperatively.
In May 2009, serum CEA rose to 34 ng/ml and abdominal CT showed enhancing liver masses at segment 2 and segment 6 sized 4.9 cm and 2.8 cm, respectively. Also, peripancreatic, mesenteric and retrocaval lymph nodes sized up to 3.2 cm were found. Metastatic unresectable wild-type RAS sigmoid colon cancer was diagnosed. He received palliative FOLFOX-6 plus cetuximab 500 mg/m2 every 14 days. At 2 months after starting treatment, thoracic and abdominal CT demonstrated partial response with 59% reduction of target lesions. Subsequent CT scan showed ongoing response. Oxaliplatin was discontinued after 14th cycle of treatment due to grade 3 neuropathy which was subsequently resolved. Cetuximab with infusional 5FU/ leucovorin was continued to the total of 103 cycles and then cetuximab every 2 weeks was maintained until present. The latest CT in July 2018 showed a 1.2 cm non-enhancing liver lesion with subcentimeter lymph nodes. The patient is doing well with occasional grade 1 skin rash.
We reported an unusual, unexpected response to chemotherapy plus anti-EGFR in a patient with metastatic unresectable colon cancer. Further molecular testing might be useful to determine unidentified potential prognostic or predictive factor in such an extreme case.