Phase II Multicenter Study of the Impact of the Therapeutic Sequence of Radiochemotherapy (50 Gy + Capecitabine + Oxaliplatin + Cetuximab) Followed by Total Mesorectal Excision Surgery Then Post-surgery Chemotherapy (FOLFOX 4 + Cetuximab) in Synchronous Locally Advanced or Metastatic Cancers of the Rectum With Metastases Resectable From the Start (T3-4 Nx or T2 N+ M1).

RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Drugs used in chemotherapy, such as capecitabine, oxaliplatin, fluorouracil, and leucovorin, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Monoclonal antibodies, such as cetuximab, can block tumor growth in different ways. Some block the ability of tumor cells to grow and spread. Others find tumor cells and help kill them or carry tumor-killing substances to them. Giving radiation therapy together with combination chemotherapy and cetuximab before surgery may make the tumor smaller and reduce the amount of normal tissue that needs to be removed. Giving chemotherapy and cetuximab after surgery may kill any tumor cells that remain after surgery.

PURPOSE: This phase II clinical trial is studying how well giving radiation therapy together with chemotherapy and cetuximab followed by surgery, chemotherapy, and cetuximab works in treating patients with locally advanced or metastatic rectal cancer that can be removed by surgery.