Ann Thorac Surg 2006;81:1548
© 2006 The Society of Thoracic Surgeons
a Pathology Division, National Cancer Center Hospital East, 6-5-1, Kashiwanoha, Kashiwa, Chiba, 277-8577 Japan
b Division of Thoracic Oncology, National Cancer Center Hospital East, Chiba, Japan
To the Editor:
The letter from Dr Kaiser  raises several concerns regarding the usefulness of our findings, selection bias in our study, and the validity of our selection measures. These are important points to consider when evaluating any study of pulmonary metastasectomy, which deserve to be addressed.
Kaiser  begins by stating that only 2% of the total patient population with pulmonary metastases will undergo a surgical resection. He implies that the study of prognostic factors may not be worthwhile if few patients are to benefit. However, 2% corresponds to 1,650 patients in Japan who underwent metastasectomy for colorectal lung metastases during a year . This represents a significant number of patients who could benefit from our findings.
Kaiser  also observes that the 5-year survival in our study is much better than earlier reports. He comments that stage IV colorectal cancer has a poor prognosis and suggests that our results are affected by selection bias. We believe that the favorable outcomes in our study are the result of our strict preoperative selection based on the precise evaluation of the patients clinical findings, measurement of a tumor marker, and systemic examination by whole body computed tomography and endoscope. Preoperative use of these multimodal criteria enables us to select those patients for whom surgery could result in a favorable outcome. Regarding the poor prognosis of stage IV disease, there are exceptions. Pawlik and colleagues  report a 5-year survival of 58% in patients who underwent hepatic resection for colorectal metastases. Our study reveals that cases with certain histopathologic characteristics, such as a lack of aerogenous spread, might represent a subset of stage IV colorectal cancers with a better postoperative prognosis . In metastatic lung tumors, it has been shown that the careful and objective selection against previously defined criteria predicts a favorable prognosis after pulmonary metastasectomy . Therefore most studies evaluating pulmonary metastasectomy apply these criteria and inherently have selection bias. However, in this study our aim is to identify prognostic factors within these highly selected cases.
Finally, Kaiser  suggests that the previously mentioned measurements are of no help in reliably predicting an individual patients prognosis or identifying patients who will benefit from one treatment or another. However, Gundry and colleagues  discuss the utility of histopathology as a predictor of prognosis in osteogenic sarcoma noting that patients with micrometastases in the resected specimens require more frequent follow-up and aggressive therapy, and overall have a poor outcome compared with those who do not . We believe that these findings are applicable to metastatic colorectal cancer as well, making histopathology a valuable and practical predictor of prognosis.
We propose that it is the responsibility of the surgeon to appropriately select patients for surgery based on the likelihood of a favorable prognosis. It is the goal of our study to provide a better definition of what these selection criteria should include.
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