Experts in treating colorectal cancer that has spread to distant sites say that the need for a better staging system for advanced disease is urgent. More specific staging could identify patients whose cancer could be cured with surgery. For others, modern chemotherapy might make curative surgery possible.
In addition, a more precise staging system, with more categories, would provide better survival prognosis.
Currently all patients whose cancer has spread beyond their colon or rectum to distant sites (metastatic colorectal cancer) are lumped together in one group, classified as stage IV or Dukes D. No difference is made for those who have liver tumors that could be surgically removed or those where chemotherapy might make surgical cure possible.
Better chemotherapy and improved surgical techniques have increased the percentage of patients with potentially curable colorectal cancer, but staging doesn’t reflect those improvements.
Surgeons no longer count the number of liver tumors to decide whether or not a patient can be helped surgically. Instead they look at whether they can remove all signs of cancer (R0 resection) and leave 20 to 30 percent of healthy liver to regrow after the operation. They also consider if the patient is healthy enough for surgery and whether cancer is limited to the liver or is more widespread in the body,
Headed by Graeme J. Poston of the United Kingdom, an international group of key research surgeons recommends revising the current staging system to reflect patients whose tumors are
- Resectable (can be completely removed safely with surgery)
- Initially unresectable (have the potential to become resectable with chemotherapy)
- Unresectable (widespread cancer outside the liver or liver disease that cannot be removed safely)
Previously surgeons were unwilling to operate if there were any additional metastatic tumors outside the liver, but new approaches have changed that. If cancer outside the liver can also be completely removed surgically, then the liver tumors are considered resectable.
To reflect the complexity of tumors outside the liver that are themselves either initially resectable, might become resectable with chemotherapy, or are unresectable from the beginning, the writers propose a grid system for staging and treatment planning.
Essential to a new staging and treatment system is a multidisciplinary team that includes surgeons, medical oncologists, radiologists, and pathologists to guide decisions about resectability and treatment.
The experts also point out that as treatment progresses, patients whose cancer was initially thought to be unresectable may become candidates for surgery so it’s critically important to reevaluate patient status and the potential for surgery throughout treatment.
A new staging system would also provide more accurate prognosis — not only for potential cure but for survival time.
In conclusion, the researchers write,
Whatever the solution, it is self evident that the current staging system (AJCC version 6, 2002) for advanced CRC is flawed, out of date, and does not reflect current treatment strategies or prognoses for patients with metastatic disease. A new staging system is therefore long overdue. The proposed restratification, particularly the grid staging system, would encourage improved patient work-up, and bring the possibility of treatment strategies aimed at long-term survival, to the attention of physicians at an early stage.
SOURCE: Poston et al., Journal of Clinical Oncology, published early online August 18, 2008.