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In Reply

Department of Surgery, St Michael's Hospital, University of Toronto, Toronto ON; and the Department of Health Policy, Management, and Evaluation, University of Toronto, Toronto, Ontario, Canada

Rieger et al are to be commended for their efforts in quality improvement and have presented an excellent example of how a quality gap can be filled—they have evaluated current practice (identifying unwanted variation), determined factors causing variation, instituted processes to reduce variation, and evaluated the impact of their intervention. They also demonstrate how the pathologist is a key player in the adequate staging of colorectal cancer. However, the most important effect of the quality intervention has not been addressed—did the intervention result in improved patient outcome? Although the number of negative nodes has been found to be associated with survival by numerous authors,^1-3 it does not necessarily follow that increasing node count will lead to improved patient survival. We are only learning about the tumor-host interactions that may influence negative node count. For example, Galon et al⁴ recently evaluated the prognostic effect of the host-immune response (as characterized by tumor-infiltrating immune cells) to colorectal cancer and found that immunologic responsiveness (as measured by the type, density, and location of immune cells within the tumor) is a better predictor of patient survival than current histopathologic staging. It is possible that the number of negative nodes is also a marker of the underlying host-immune response to colorectal cancer. If this is true, attempts to increase the negative node count by improvements in surgery and/or pathologic evaluation will not have a meaningful effect on patient outcome.

AUTHOR'S DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST

The author indicated no potential conflicts of interest.

ACKNOWLEDGMENTS

Nancy N. Baxter is supported by an American Society of Clinical Oncology career development award and a Canadian Institute of Health Research New Investigator award.

REFERENCES

1. Johnson PM, Porter GA, Ricciardi R, et al: Increasing negative lymph node count is independently associated with improved long-term survival in stage IIIB and IIIC colon cancer. J Clin Oncol 24:3570-3575, 2006[Abstract/Free Full Text]

2. Chen SL, Bilchik AJ: More extensive nodal dissection improves survival for stages I to III of colon cancer: A population-based study. Ann Surg 244:602-610, 2006[CrossRef][Medline]

3. Le Voyer TE, Sigurdson ER, Hanlon AL, et al: Colon cancer survival is associated with increasing number of lymph nodes analyzed: A secondary survey of intergroup trial INT-0089. J Clin Oncol 21:2912-2919, 2003[Abstract/Free Full Text]

4. Galon J, Costes A, Sanchez-Cabo F, et al: Type, density, and location of immune cells within human colorectal tumors predict clinical outcomes. Science 313:1960-1964, 2006[Abstract/Free Full Text]

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