Posted by Kate Murphy on July 11th, 2006
Does the current system of staging all patients with metastatic colon or rectal cancer in one group (stage IV) still make sense? Is it time for a new system that defines stages that reflect the potential for surgical cure?
In the June 20, 2006 issue of the Journal of Clinical Oncology Drs. Graeme Poston, Rene Adam, and Jean-Nicolas Vauthey consider that question in an article Downstaging or Downsizing: Time for a New Staging System in Advanced Colorectal Cancer?
Ten years ago, very few patients with metastatic colon or rectal cancer survived five years. Less than 1% of those whose cancer had spread but could not be removed surgically lived beyond five years. However, for about 10% of patients surgery to remove cancer that had spread to their liver was possible, and for that 10%, a surgical cure was possible. Thirty to forty percent of that small group survived.
Time has changed that situation considerably. Better, safer surgery for metastatic tumors is now available. More patients are considered eligible for surgery. And improved chemotherapy can now reduce tumor size and make patients who were initially not eligible for surgical treatment resectable.
Resection is now possible for a much wider range of patients including some who have mets outside the liver if they can also be successfully surgically removed. According to Poston and his colleagues a broader definition of liver resectability makes surgery much more feasible:
Now the definition of resectability with curative intent is the ability of the surgeon to clear, with negative margin, all measurable disease from the liver while leaving a healthy future remnant liver of 20% of the total liver volume. …. Liver resection is now considered selectively in some subsets of patients with limited resectable extrahepatic disease. Hilar lymph node metastases; lung, ovarian,and adrenal metastases; and local or regional recurrence are no longer formal contraindications.
New criteria for selecting patients makes at least 20% of patients with liver-only metastases eligible for surgery at the beginning of their cancer treatment. Statistical evidence is finding that up to 50% of those patients are surviving 5 years or more. Similar results are emerging for patients with lung-only mets.
New chemotherapy, not available ten years ago, also contributes to potential resectability of liver mets. Depending on the study, survival after surgery after such chemotherapy ranges from 6% to 60%.
Given this new situation, the authors propose a new system of staging for metastatic colorectal cancer that takes into account the potential for surgical cure. A better system would help patients and physicians decide on the best treatment strategies from the very beginning. It would also allow better comparison of results of clinical studies.
The proposal system would divide the current stage IV colorectal cancer into two substages, each with three categories of their own:
- IV R — Resectable disease
- IVRa — resectable liver only
- IVRb — resectable extrahepatic only (spread outside of the liver only)
- IVRc — resectable both liver and extrahepatic
The writers warn that experienced surgeons and multi-disciplinary teams be involved in staging to prevent misdiagnosis that might limit the choice of patients for surgery that might lead to long-term remission of their cancer.
The proposals outlined earlier should be subjected to expert surgical review and be tested robustly in real life because there could be fears that nonexpert surgeons and nonsurgeons might be tempted to stage such patients before referral to a specialist center.
Given the considerable progress made in both surgery and chemotherapy in the past ten years, a new staging system might well improve the chance that an individual patient would be directed to the best treatment strategy — one that might save his life.
Poston, Adam, and Vauthey conclude:
Advanced colorectal cancer is rapidly evolving from an acute terminal illness into a chronic and manageable condition. The increasing evidence of chemotherapy response that is sufficient to render previously nonresectable disease now resectable with curative intent opens up the possibility that achieving resectability could become a recognized end point for future clinical trials in medical oncology. Although this new classification proposal would need to be validated prospectively, we believe that there is sufficient evidence to support its adoption since prognosis (within stage IV) is now clearly different between these two groups in relation to resectability and also to sites (single and multiple) of metastatic disease.
Poston et. al. Journal of Clinical Oncology, Vol 24, No 18 (June 20), 2006: pp. 2702-2706
WHAT THIS MEANS FOR PATIENTS
While the proposed staging system has not yet been agreed to, newly diagnosed patients can ask their surgeons and oncologists to work together to decide whether or not mets are resectable or potentially resectable. A multidisciplinary team at a major cancer center is probably the best resource for making this critically important first decision.
If mets are not resectable, ask if it is possible that chemotherapy can reduce them and make surgery possible. Again, involving a team of oncologists, surgeons, and radiologists is important. Get a second — or third — opinion before deciding that resection is impossible.