Prognostic value of malignant cells in pleural lavage at thoracotomy for bronchial carcinoma
Introduction
Despite seemingly radical surgery, the majority of all patients operated on for bronchial carcinoma will die from their disease. The prognostic importance of the TNM system has been clearly demonstrated. However, even patients who pre- and postoperatively have been classified as stage Ia (tumor less than 3 cm in diameter, no lymph node metastases) will in a considerable percentage later show metastases. It has therefore been suggested that even seemingly radically operated patients should be treated postoperatively with radiation or cytostatics. However, whether such an approach would improve prognosis is still not known, and a number of patients whose tumor was in fact radically operated would suffer an unnecessary treatment. Thus, a prognostic factor that could identify patients with an increased risk for tumor relapse would be of great clinical importance.
In 1958, Spjut et al. [1]showed that malignant cells could be demonstrated in a fairly high percentage in the fluids obtained by washing the pleural cavity after surgery for bronchial carcinoma. The authors were concerned that these cells had contaminated the pleural cavity because of the surgery. However, it has later been demonstrated that malignant cells can occur in the pleural cavity even before surgery. This occurrence of malignant cells in pleural lavage performed at operation might be an indicator of poorer prognosis, other factors being equal 2, 3, 4, 5, 6, 7. It was decided to test this hypothesis in clinical material.
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Patients
The material consisted of 224 consecutive patients who had been operated due to verified or strongly suspected bronchial carcinoma, preoperatively staged by computed tomography (CT scan) as stage I or II (T1–2, N0–1 or T3N0) and where radical surgery was considered to have been performed by the surgeon.
Methods
After opening the thorax and before manipulation or palpation of the lungs, 300 ml of physiological saline solution was installed into the pleura. The fluid was gently disturbed by hand,
Clinical findings
Of the 224 patients, 163 were confirmed after histological investigation of the surgical specimen to having had a bronchial malignant tumor. Seven patients were not radically operated and were therefore excluded from analysis, and another six patients had to be excluded because of missing data. Twelve patients had a carcinoid tumour and were analyzed seperately, leaving 138 radically operated patients with bronchial carcinoma. Eighteen patients were shown to have metastatic disease from some
Discussion
The occurrence of malignant cells in the pleura in patients with tumors not reaching the pleural surface could at first be seen as surprising. However, it is well known that there is a `pleural drift' of inhaled particles from the lung parenchyma towards the periphery and further passage into the pleural space has also been described. Thus, the spread of tumor cells to the pleura does not need to be explained. In some of the patients a fine-needle biopsy of the tumor had been performed before
Conclusion
There is some prognostic value in performing a pleural lavage. However, as a general rule, the more advanced the tumor, the higher the percentage of positive pleural washings, and therefore the new information is limited. Consequently, we cannot recommend at present that pleural lavage be used as a criterion for postoperative radiological and/or cytostatic treatment. According to the TNM classification, a malignant exudate is classified as T4 with a very poor prognosis. Clearly, the occurrence
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