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Istanbul, Turkey
Correspondence to: Akif Turna, MD, Cami Sok, Muminderesi Yolu, Emintas Camlik Sit, No:32/22, Sahrayicedid, Kadikoy 81080 Istanbul, Turkey; e-mail: aturna{at}turk.net
To the Editor:
We read with great interest the article by Sawabata and associates1 in CHEST (October 2000). The authors present data of a study concerning the potential of malignant cell spread with fine-needle aspiration. Although physicians in some institutions perform fine-needle aspiration routinely and safely in order to obtain histologic diagnosis of thoracic masses with a high rate of accuracy,2 a number of centers do not utilize this method because of possible complications, such as seeding and pneumothorax, especially in patients with COPD. We would like to express a few of our comments on that study.
Firstly, concerning the utilized model of the study, the lung was deflated during and after fine-needle aspiration. Therefore, there is a lack of a counter-balancing effect against the chest wall and a lack of sealing function against the shedding possibility of tumor cells. Since the opposed tissue pressure created by inflated airways and alveoli was decreased in a deflated lung, theoretically tumor cells might anticipate less intercellular pressure of extracellular matrix; therefore, the possible chance for tumor cells to exfoliate outside the lung could be suggested to be higher than that of living lung. That hypothesis could have been tested by comparison of the presence of tumor cells in the pleural irrigation fluid from the fine-needle aspirated deflated and artificially reinflated specimens. We think that that would be the necessary negative control of the study group.
In the study, it was reported that the number of spilled tumor cells was found to be higher, but increased tumor cell shedding does not necessarily result in successful implantation of the tumor cell population because of the resistance of immune system of the host against tumor cells as proposed by the "immune surveillance" theory.3 In order to test this possibility, aspiration tracts could be pathologically examined. Implantation of tumor cells has been known to be extremely rare, such as 1 in 4,000 transthoracic needle biopsy procedures,4 and has been the subject of a few case reports in medical journals.
This study also inspired us to search for evidence of poorer survival in inoperable stage-matched patients who underwent fine-needle aspiration for diagnosis. We were unable to find any study on this respect. For this reason, we think it is unlikely that needle aspiration has a perilous tumor seeding effect in terms of tumor implantation risk in those patients. We are also grateful for that hypothesis-creating innovative study, which could be a basis of further studies.
References
Toneyama National Hospital Osaka, Japan
Correspondence to: Noriyoshi Sawabata, MD, FCCP, Division of Surgery, Toneyama National Hospital, 5-1-1 Toneyaman Toyonaka, Osaka, 560-8552 Japan; e-mail: nori{at}toneyama.hosp.go.jp
To the Editor:
I appreciate the response to our article1 concerning the potential of malignant cell spread following fine-needle aspiration cytology (FNAC) from Dr. Bedirhan and Dr. Turna. They pointed out the dissociation between an in vivo and ex vivo lung. As they said, the inflated lung over the tumor can protect against the spread of malignant cells through the tract following FNAC. However, most of the tumors that underwent FNAC were peripherally located and associated with pleural indentation. Thus, the lung over the tumor does not seem to be completely inflated. And so I believe the possibility of spreading tumor cells is similar between an in vivo and ex vivo lung.
I also believe in the "immune surveillance theory." Effusion-associated lymphocytes are revealed to have depressed cellular function in the malignant effusion with lung cancer.2 And so it is speculated that the spread of malignant cells has a low potential of implantation. Surgical patients with lung cancer have a good performance status and may have a normal immune function. We have performed a retrospective study,3 which revealed the technique did not affect relapse and survival. By contrast, patients with advanced lung cancer may have a depressed immune system. Therefore, it is important to search for evidence of pleural carcinomatosis and poorer survival in inoperable patients with advanced lung cancer.
To summarize our opinion, FNAC has the potential to seed malignant cells that rarely implant among operable patients, but the possibility of implantation is controversial among inoperable patients with advanced lung cancer.
References
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