Keith S. Naunheim, MD

Saint Louis, Missouri

Thoracoscopy has been and continues to be widely utilized for a variety of disease processes in the lung, both benign and malignant. VATS procedures used in known benign pulmonary conditions include bleb resection and pleurodesis for recurrent pneumothorax, lung biopsy for interstitial disease and lung volume reduction for endstage emphysema. Thoracoscopic procedures are also popular for definitive diagnosis of indeterminate lesions such as recurrent pleural effusions and isolated pulmonary nodules.

There are certain situations in which further diagnostic or therapeutic maneuvers are performed thoracoscopically in the setting of recognized malignancies. Such situations include staging of intrathoracic adenopathy not amenable to cervical mediastinoscopy, prethoracotomy staging of lung lesions suspected of T4 status and therapeutic limited excision of a known lung primary in a severely compromised patient (such as during lung volume reduction surgery). It is safe to say that in all of these situations, VATS plays a useful and important role which should not be underestimated.

The real controversy arises when one discusses the usage of VATS for two separate clinical situations dealing with known malignancy: thoracoscopic anatomic lung resection for lung cancer and resection of pulmonary metastases with curative intent.

Many surgeons have argued against thoracoscopic lobectomy suggesting that it is a bad operation since it is difficult to perform and cannot be easily taught to others. I would suggest that similar arguments were used in the 1950’s when lobectomy was first introduced as an alternative to pneumonectomy for the treatment of lung cancer. Surgeons able to perform laparoscopic fundoplications and heart valve replacements can probably learn VATS lobectomy if they so desire. The pertinent arguments against thoracoscopic lobectomy and pneumonectomy deal with issues of safety, adequacy of lymph node dissection, postoperative pain and function, length of stay, subcutaneous tumor implantation and long-term survival.

Early randomized trials demonstrated that thoracoscopic lobectomy could be safely accomplished but that it held no significant clinical advantage over the open technique. These studies were performed early in the evolution of VATS lobectomy when experience was extremely limited and current techniques had yet to be developed. These studies might give different results if conducted today.

Recent reports by McKenna (1) Yim (2), Walker (3), Kaseda (4), Roviaro (5), Lewis (6) and Hermanssohn (7) demonstrate excellent results with regard to morbidity, mortality, length of stay and conversion rate. Lymph node evaluation can be accomplished either with preoperative mediastinoscopy or with intraoperative sampling or dissection. A recent report by Kondo (8) demonstrates an excellent yield with regard to the number of mediastinal nodes resected thoracoscopically. The issue of tumor implantation at the trochar site has virtually disappeared with the use of a specimen removal bag. Long-term survival results, perhaps the most critical indicator of success or failure, are just now beginning to be assessed. These appear to be similar if not identical to survival rates found with open procedures.

The above mentioned reports demonstrate that for appropriately selected patients, thoracoscopic lobectomy can be safely and effectively performed by surgeons experienced in VATS techniques. This does not mean that it should be the technique of choice for all surgeons. The major purported advantages of VATS lobectomy are decreased pain and shortened return to functional status. A prospective randomized study will be required to confirm or refute these assertions. Until then, thoracoscopic lobectomy remains an acceptable alternative rather than the gold standard.

The primary argument against VATS resection of lung metastases is that the combination of preop imaging and intraoperative examination will not allow for identification and excision of all metastatic lesions. McCormack (9) demonstrated that after VATS excision of all identifiable lesions, a thoracotomy allowed for identification of additional malignant lesions in just over half of the patients. The report suggests that VATS resection will lead to similar inadequate identification of lesions resulting in unresected lesions and an inferior survival. The report has been criticized for utilization of obsolete imaging technology (no helical CT scans), poor radiographic control (only 66% of scans reviewed for accuracy) and reliance on surgeons inexperienced in VATS techniques.

The initial report of the International Registry for Lung Metastases (10) identified only three factors that appeared to affect survival following resection of lung metastases: interval of 36 months since primary tumor treatment, presence of a solitary metastasis and incomplete resection. The first two factors will not be influenced by the surgical approach (thoracotomy, sternotomy, VATS). Incomplete resection, however, may be significantly affected and is the crux of the argument used against VATS resections. It must be critically examined.

What is meant by incomplete resection? Prior reports identifying incomplete resection as a survival factor have all been the result of open procedures. The only "incomplete" resections in such cases dealt either with bulky disease contiguous with vital structures or with nodules too numerous to remove without significant pulmonary compromise. It’s no surprise that such a patient will have a shortened lifespan. This is not the same as a missed and unresected 4 mm metastasis! One must wonder if this is a rare event even in open procedures.

Are lesions missed even during open procedures thus requiring a second thoracotomy? The International Registry report documented that 25% of resected patients had recurrent pulmonary metastases, probably persistent disease missed at the first exploration. Three quarters of these patients had a second thoracotomy.

Does the need for a second thoracotomy result in inferior survival? The International Registry reported a better survival in those patients than in the first time operative patients (44% vs. 34% five year survival). This suggests there is no deleterious effect on long-term survival if a missed lesion is excised in a metachronous as opposed to synchronous setting. This has also been confirmed by Saltzman (11) and Roth (12).

Has a VATS metastasectomy series reported survival figures comparable to open series? Landreneau (13) recently reported a multiinstitutional series of 80 patients undergoing VATS resection for lung metastases from colon cancer. His five year survival rate of 31% and local recurrence rate of 26% seem remarkably similar to those reported from open procedures by the International Registry (34% and 25%), the Mayo Clinic (30% and 46%).

Is VATS resection the procedure of choice for lung metastases? As with any other surgical tool or technique, thoracoscopy must be utilized in the correct setting for the appropriate patient. Preoperative imaging should include a fine cut spiral chest CT scan performed during a single breath hold. Metastases should not be bulky (<3 cms) or centrally located and thus inaccessible to VATS. Multiple lesions of varying sizes suggest that there will be minute lesions not identifiable by visual inspection or CT imaging (and probably not by palpation). Such patients are likely best treated in open fashion. However, VATS can be utilized for a peripheral solitary lung metastasis with a reasonable expectation of complete resection and cure. Those who do not agree due to the notion of potential "missed" lesions must proceed with bilateral exploration if they are to be consistent and intellectually honest.