Urgent need for a new staging system in advanced colorectal cancer

Despite recent advances in the medical treatment of metastatic colorectal cancer (mCRC), which include irinotecan- and oxaliplatin-based first-line regimens, the concept of planned sequential therapy involving three active agents during the course of a patient's treatment and the increasing use of targeted monoclonal antibodies, 5-year survival rates for patients with advanced CRC remain unacceptably low. For patients with CRC liver metastases, liver resection remains the only chance of cure, with 5-year survival rates ranging from 25% to 40%. However, 80% to 85% of patients with stage IV CRC have liver disease which is considered unresectable at presentation. The rapid expansion in the use of improved combination chemotherapy regimens plus or minus biologics, to render initially unresectable metastases resectable has increased the percentage of patients eligible for potentially curative surgery. However, the current staging criteria for CRC patients with metastatic disease do not reflect these recent changes or the fact that there is also a large variation in the survival of patients with stage IV CRC. For example the survival for a patient with a solitary, resectable liver metastasis is better than that for a patient with stage III disease. A new staging system is therefore needed that acknowledges both the improvements that have been made in surgical techniques for resectable metastases and the impact of modern chemotherapy on rendering initially unresectable CRC liver metastases resectable, while at the same time distinguishing between patients with a chance of cure at presentation and those for whom only palliative treatment is possible.

Presurgical chemotherapy in patients being considered for liver resection

The liver is a frequent site of metastatic disease for colorectal cancer patients. Approximately 15% of patients have liver metastases at diagnosis and another 50% develop metastatic disease to the liver over the course of their disease. Advances in systemic chemotherapy and surgical techniques for hepatic resection have led to longer survival times for these patients. There is no doubt that unresectable patients benefit from systemic chemotherapy. For patients who have resectable disease, the timing of chemotherapy is still not clear. This review addresses the pros and cons of presurgical chemotherapy. The benefits of preoperative chemotherapy include decreasing tumor size, controlling micrometastatic disease, assessing activity of chemotherapy, improving chemotherapy tolerance, and perhaps allowing some prediction of the success of liver resection. The risks for presurgical chemotherapy include liver toxicity, the risk for progression or growth of new sites, secondary splenomegaly, selection of resistant clones, and the possibility of leaving behind active tumor that is no longer seen because of a complete radiographic response. The challenge for the future is to develop a multidisciplinary team approach that can design the best treatment plan for patients with liver metastases.

Irinotecan in the treatment of colorectal cancer

Irinotecan, a water-soluble, semisynthetic derivative of camptothecin, is a key component of first- and second-line treatment regimens for metastatic colorectal cancer (CRC). In the first-line treatment of metastatic CRC, the results of two prospective, multicenter phase III trials have shown that the combination of irinotecan with bolus or infusional 5-fluorouracil (5FU)/leucovorin (LV) can significantly prolong survival compared with 5FU/LV alone, with a manageable side effects profile. In addition, irinotecan-based regimens, with or without oxaliplatin, may improve resectability of metastases and further increase patient survival. Studies of irinotecan in the first-line setting in combination with newer agents, such as bevacizumab, have shown impressive overall survival. In the second-line setting, irinotecan has demonstrated efficacy superior to that of best supportive care. Initial studies of irinotecan plus bolus 5FU/LV, and the preliminary results from trials of irinotecan plus infusional 5FU/LV in the adjuvant setting, have been disappointing; however, for the largest trial, the Pan-European Trial in Adjuvant Colon Cancer, results with sufficient follow-up are pending. Irinotecan has an acceptable tolerability profile and is not associated with cumulative toxicities in patients with metastatic CRC; regimens containing irinotecan extend treatment duration and improve survival. New regimens and adjunctive therapies are being explored to reduce the incidence of common complications of irinotecan treatment, such as diarrhea and neutropenia.