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[Specific treatment situations in metastatic colorectal cancer].

As far as the management of primary resectable liver metastases is concerned, three approaches are currently competing with each other: surgery alone, surgery with pre- and postoperative chemotherapy, and surgery with postoperative chemotherapy alone. The core of the argument for pre- and postoperative chemotherapy in these patients is the European Organisation for Research and Treatment of Cancer (EORTC) 40983 study, which concluded that, in comparison with surgery alone, perioperative chemotherapy improved the 3-year progression-free survival (PFS) by 7 months. In contrast to this, there are two smaller studies--at a somewhat lower strength of evidence-- indicating that adjuvant chemotherapy extends PFS by 9.1 months compared with surgery alone. In Germany, the adjuvant approach continues to be favored in many places; this can also be seen in the formulation of the S3 guideline. In patients with unresectable liver metastases--with the associated difficulty of classification due to the lack of clear and definitive criteria--preoperative systemic therapy to induce 'conversion' is indicated, in order to allow secondary resection. In KRAS wild-type tumors, high response rates (in terms of a reduction in size of the metastases, such as according to RECIST (Response Evaluation Criteria in Solid Tumors)) and a high conversion rate are achieved using a cetuximab/chemotherapy combination. Triple chemotherapy combinations with 5-fluorouracil (5-FU), oxaliplatin and irinotecan also produce high response rates. Bevacizumab/chemotherapy combinations have led to a high number of complete and partial pathohistological remissions in phase II studies; these seem to correlate with long survival times. In the absence of long-term survival data, it therefore seems to remain unclear as to what is the best parameter to use in order to assess the success of preoperative treatment. Lung metastases, too, or local peritoneal carcinomatosis can nowadays be operated on in selected patients with a good prospect of long-term remission or even cure. The surgery should, however, generally only be carried out in experienced centers, especially in the case of peritoneal carcinomatosis. For synchronous metastasization, the appropriate management depends on the size and extent of liver metastases and of the primary tumor. Small, peripherally lying and safely resectable liver metastases can be removed before or at the same time as the primary tumor, especially if a hemicolectomy is being carried out. If the metastases are unresectable and there is no bleeding or stenosis, the primary tumor can also be left in situ and systemic chemotherapy can be carried out first. However, it should be borne in mind that, according to current data, palliative resection of the primary tumor combined with systemic therapy leads to longer overall survival than does chemotherapy alone. Whether resection or chemotherapy should be done first therefore depends on the patient's clinical situation.