|
Intervention for Stages I and II By Octavio E. Pajaro MD, PhD |
| The impetus to perform minimally invasive operations is occurring in all fields of surgery. The
rationale for this lies in the belief that minimally invasive surgery will lead to less pain, faster
recovery and less time in hospital and thus, potentially reduce healthcare costs. The
assumption is made that if "minimally invasive" procedures can be performed with at least equal safety and
efficacy as standard operations, then they are the preferred therapy. It is difficult to quantitatively defend
these arguments as many variables confound the ability to easily compare minimally invasive procedures
with standard operations and studies often involve too few patients to make fair conclusions.
Nonetheless, it would be natural for anyone including surgeons facing possible operative intervention to hope
that a "minimal" approach would be feasible, whatever the illness. We are thus justified and obligated
to continue to explore minimally invasive procedures, keeping in mind that problems today may
be overcome by improved technology in the future.
In patients with lung cancer, video-assisted thoracoscopic surgery (VATS) represents the main minimally invasive technique being explored. Swanson and Batirel1 have recently reviewed the indications and techniques of VATS resection for lung cancer. The use of VATS is being investigated in all aspects of lung cancer—diagnosis, staging and definitive surgical therapy. Information gained from imaging methods will play an important role in defining the indications for the use of VATS and long-term well-controlled studies will be needed to prove the effectiveness of minimally invasive techniques. The ultimate indications for VATS lung cancer operations will depend on the answers to several important questions. Does VATS provide accurate staging information in patients with lung cancer? Can an appropriate lymph node dissection be performed using VATS? Can a complete surgical resection be performed? Is there any risk of tumor seeding? Are survival and recurrence rates at least as good as a standard thoracotomy approach? Technique of video-assisted thoracoscopic surgery (VATS) Similar to laparoscopic surgery, VATS uses a real-time two-dimensional video image of the thorax via a rigid thoracoscope (10-12mm in diameter) inserted through a small incision in the chest just big enough to fit the scope. The thoracoscope selected can have either a zero or 30 degree angle with the choice completely surgeon dependent. Further 3-5cm incisions are required through which instruments are placed. In general, a biopsy and exploration can usually be performed with a total of three incisions of similar length. These incisions can then be used to place drains or chest tubes upon completing the procedure. The patient is positioned in the lateral decubitus position as for a standard posterolateral
thoracotomy incision. The small incisions are placed in a way to maximize the viewing angles and increase the
working space for the instruments. Thought is given to the fact that all thoracoscopic approaches could result
in a full thoracotomy. Thus, one hopes to minimize the chance that a thoracotomy is performed with
three additional incisions that are neither part of the thoracotomy wound nor incorporated in chest
tube placement. If a larger resection is performed, an incision larger than 5cm will be required to remove
the specimen. The size of this additional incision will be determined by the size of the specimen. The
specimen must be removed intact to confirm tumor margins and thus, complete the staging. In addition,
the specimen should be removed in an impermeable endoscopic bag in order to decrease the possibility
of tumor seeding. As the number of incisions and the size of the incisions increase, the meaning
of "minimal" comes into question and the proposed benefits are less likely. The purpose of this article
is to discuss the use of video-assisted minimally invasive surgery and not the benefits of hybrid
operations in which a surgeon performs a full thoracotomy and uses a thoracoscope to improve operative
exposure. Nonetheless, there is no clear definition of what constitutes "minimal." Terms such as
mini-thoracotomy and utility thoracotomy are used almost interchangeably and can describe 5cm to 10 cm incisions.
The length of the incision may only refer to the length of the skin incision. The intercostal muscles can be
incised beyond both corners of the skin incision. Perhaps the most reliable indicator of what is truly
minimal In order to perform VATS, single-lung ventilation is required in order to gain space for the instruments in the thoracic cavity and to allow visualization of structures. This is generally accomplished through a double-lumen endotracheal tube. While this is standard for the majority of thoracic lung cancer operations, in certain cases, two-lung ventilation can be used to perform resections or biopsies in patients. As a result, the patient must tolerate single-lung ventilation in order to undergo a VATS procedure. This must be kept in mind when considering a minimally invasive approach in patients with poor lung function. VATS cannot be performed in patients with severe adhesions. Patients who are likely to have adhesions because of previous surgery, infection, pleurodesis, or tumor itself are unlikely to be offered a thoracoscopic approach. Visualization is greatly hampered by adhesions and the placement of instruments may be impossible without the ability to fully collapse the lung on the operative side. Two important limitations of thoracoscopic lung surgery are the loss of a three-dimensional operative view and the loss of the ability of the surgeon to use tactile sense. The first issue is becoming less of a limitation as surgeons continue to gain experience using video images and become more comfortable judging spatial relations on a two-dimensional image. In addition, continued improvement in optical technology and the possibility of three-dimensional images in the future will most likely eliminate this problem altogether.5 The second issue is much more difficult to overcome, as no technology as of now can truly replicate the sense of touch. Palpation is important both for finding small or occult pulmonary lesions not seen on pre-operative imaging studies and for assessing resectability in tumors adherent to adjacent structures. In the future, combined imaging and thoracoscopic techniques may help identify small lesions intraoperatively.6 Diagnostic procedures, biopsies and wedge resections Biopsies of intrathoracic lesions are now routinely performed using VATS. With the aid of a thoracoscope, it is possible to drain effusions, perform pleural and lung biopsies, and resect small nodules or even Stage I lung cancers with a wedge resection. The decision to use VATS for resecting small nodules and masses depends on the size and location of the tumor. Small peripheral lesions near the visceral pleura are more likely to be found with a thoracoscope. Generally, lesions greater than 10mm are more easily seen without the need for direct palpation. Lesions deeper in the parenchyma or closer to the hilum become more difficult to find and more dangerous to resect using VATS. Attempts at biopsy with radiologic techniques are usually performed prior to proceeding with a VATS biopsy when the main first objective is to obtain a diagnosis. A recent study by Shennib et al. (2000) confirms the feasibility of wedge resecting stage I lung nodules using VATS in high risk patients whose lung function would make it unlikely to tolerate a lobectomy. Post-operative radiation therapy was used in these patients. Cancer-free survival and recurrence rates were reasonable and indicate that this minimal approach for small Stage I lung cancers in high risk patients may be the safest option. Therapeutic procedures In order to perform a therapeutic oncologic lung cancer procedure it is necessary to have an accurate pre-operative and intraoperative staging as well as a complete surgical resection. Intraoperative staging requires the ability to fully examine the entire lung and to perform a complete lymph node examination. In light of this, it is understandable that VATS is most seriously being evaluated for Stage I and II non-small cell lung cancer. The feasibility of performing lobectomies is currently being evaluated. It is felt that the indications for VATS pneumonectomy are currently rare and the indications for resections less than a lobectomy are unusual in lung cancer other than as described above in the study by Shennib. The ability to exclude T4 nodules (satellite lesions in the same lobe as the primary cancer) or M1 nodules (satellite lesions in a lobe not containing the primary mass) without palpation will primarily going rest on the pre-operative imaging studies. Lymph node dissection, however, is being shown to be feasible in centers with significant VATS experience. High paratracheal lymph nodes and subcarinal lymph nodes (levels 2, 3, 4, and 7) can also be assessed via mediastinoscopy prior to thoracoscopy. Aortopulmonary window nodes (levels 5 and 6) can only be assessed via the left thorax and periesophageal and inferior pulmonary ligament nodes (levels 8 and 9) need to be assessed intrathoracically. Data does indicate that VATS nodal dissection is feasible.7 Kaseda et al. (1997)8 reported their experience with 88 VATS lobectomies and two VATS pneumonectomies. Of these patients, 66 patients were diagnosed with Stage I lung cancer. Thirty-six of these patients underwent extended lymph node dissection. A 5-8 cm anterolateral thoracotomy was made in the fourth or fifth intercostal space. Two more access incisions were required. The authors argue that after gaining experience with 300 "less-demanding" thoracoscopic procedures, they felt ready to attempt anatomic resections with complete lymph node dissections. A more recent study by Thomas et al.(2002)9 reports results of 110 VATS procedures for lung cancer and compares their results with 405 standard thoracotomies. Their results indicate similar five-year survival for Stage IA and IB patients. No significant differences were shown in recurrence rates. No recurrences were observed at the port sites or the thoracotomy incision. Unfortunately, their methods involved a rib-separating mini-thoracotomy. A national multi-center trial evaluating video-assisted non-rib separating lobectomies has recently closed and the data is being evaluated. This trial investigated the use of VATS for peripheral nodules less than 3cm suspected to be non-small cell lung cancer. According to Swanson and Batirel (2002)1 early data suggest that lymph node dissection and lobectomy are feasible using this technique. Outcomes Because of the varied techniques currently employed, it is difficult to make definitive conclusions as to the effectiveness of VATS in lung cancer. Morbidity and mortality rates appear to be similar to standard thoracotomy.10, 11 Survival and recurrence rates are not fully known as few prospective trials are available or as of yet reported. Complications are similar to open techniques, including bleeding, infection and air leak. Rates of conversion to open technique are in the 10% range. Pain syndromes may be reduced but the use of mini-thoracotomy and rib-separating techniques makes it difficult to prove with current data. Conclusions Evidence is gradually accumulating indicating that video-assisted thoracoscopic surgery is a feasible and perhaps better alternative for the treatment of Stage I and Stage II non-small cell lung cancers. As methods continue to improve for the evaluation of the mediastinal lymph nodes, surgeons will feel more comfortable that a true cancer operation can be performed. It is imperative that the techniques be standardized and that a non-rib separating technique be employed to increase the ability to compare results and increase the likelihood of benefiting from a truly "minimally invasive" procedure. Accurate staging will have to rely on pre-operative imaging techniques to assess T4 and M1 lesions. Long-term studies are needed to compare survival and recurrence rates. REFERENCES
Jacksonville Medicine 2003 |
|
What's New
·
Northeast Florida Medicine Journal ·
Know Your Physician
· Legal
& Legislative
Duval County Medical Society
·
555 Bishopgate Lane
·
Jacksonville, FL 32204
|