Pathologic response of primary rectal cancer to oxaliplatin-based chemotherapy.

Management of stage IV rectal cancer is controversial, and different strategies may be useful. Preoperative chemotherapy for liver metastases might cause pathologic changes over the primary rectal tumor. In this study, the authors show the pathologic regression of the primary rectal tumor after neoadjuvant chemotherapy treatment. Patients suffering stage IV rectal cancer underwent surgery after oxaliplatin-based chemotherapy. Age, gender, type of surgery, carcinoembryogenic antigen (CEA) level, presence of metastatic disease in one or multiple organs, ypT, ypN, and circumferential resection margin (CRM) were evaluated. Pathologic response of the primary tumor was estimated by using three conventional grading systems and a semiquantitative system assessed by the amount of viable cells out of the total tumor area macroscopically described. Fibrosis, necrosis, and colloid response were evaluated with a semiquantitative system. A complete pathologic response (ypTO) was found in one patient. A good response was observed in the 41.6% of the cases with all grading systems. Presence of fibrosis in the primary tumor was found in six cases. No patient showed CRM involvement. One patient developed a local recurrence. Oxaliplatin-based chemotherapy for stage IV rectal cancer provides high rates of pathologic regression in the rectal tumor and may allow surgery without CRM involvement.