The treatment of non–small cell lung cancer is stage specific. Aggressive staging is associated with improved stage-specific prognosis. Available methods of surgical staging include scalene node biopsy, mediastinoscopy, anterior mediastinotomy, and thoracoscopy. In this article the various surgical staging methods are described and their respective roles are discussed.
In non–small cell lung cancer, as with many other malignancies, prognosis is dependent on disease stage. It has been proposed that recent improvements in stage-specific survival are attributable to increased accuracy of pretreatment staging of non–small cell lung cancer. As the treatment of non–small cell lung cancer has become increasingly stage specific, accurate pretreatment staging has become increasingly important.
Modern pretreatment staging of non–small cell lung cancer utilizes a variety of methods to evaluate patients for possible spread of tumor to distant sites, or to local and regional lymph nodes. Staging methods include imaging with computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) scans. Lesions suspicious for nodal involvement or distant metastatic spread that are identified on imaging are then biopsied for confirmation. Often a needle biopsy of such suspicious lesions can be achieved percutaneously under ultrasound or CT guidance, or endoscopically with the help of transesophageal endoscopic ultrasonography (EUS) or endobronchial ultrasonography (EBUS). Although it is possible to demonstrate the presence of metastatic disease with a positive needle biopsy, the absence of metastatic disease must be proven more rigorously, usually with a surgical biopsy.
Scalene node biopsy
Non–small cell lung cancer may involve supraclavicular or scalene lymph nodes. Under such circumstances, cure cannot be achieved by surgical resection. Involvement of supraclavicular lymph nodes with metastatic cancer may be suspected if the lymph nodes appear enlarged on CT scan or hypermetabolic on PET scan. Percutaneous needle biopsy of involved supraclavicular lymph nodes, with or without ultrasound guidance, is often diagnostic of metastatic disease. In some instances, however, a hypermetabolic supraclavicular node may not be large enough to allow successful percutaneous needle biopsy. Under such circumstances, a formal scalene node biopsy may be helpful.
Technique
With the patient in the supine position under general endotracheal anesthesia, the neck is hyperextended by placing a roll under the shoulders. The arms are tucked at the patient’s sides, the head is turned to the contralateral side, and the neck and upper chest are prepared and draped. A 3-cm horizontal supraclavicular incision is made over the lateral border of the sternocleidomastoid muscle. The muscle is retracted medially; to enhance exposure, its lateral fibers may be divided.
The scalene fat pad is bordered by the subclavian vein inferiorly, the internal jugular vein medially, and the omohyoid muscle laterally. Its deep border is formed by the scalenus anticus muscle, with the phrenic nerve lying in its sheath. The fat pad is excised using blunt dissection aided by judicious use of electrocautery. The transverse cervical and inferior thyroid vessels typically course through the scalene fat pad, and may be ligated and divided. Care should be taken to avoid injury to the phrenic nerve. On the left side, special care should be taken to avoid injury to the thoracic duct.
After the fat pad has been completely excised and hemostasis has been secured, the incision is closed in layers. Placement of a drain is not required. The platysma muscle and subcutaneous fat are reconstituted using a running absorbable suture. The skin is closed using a running subcuticular absorbable suture. Steristrips may be used, and a light adhesive bandage is applied.
Mediastinoscopy
In the presence of mediastinal lymph node involvement, it is unlikely that non–small cell lung cancer can be cured by surgical resection alone. In such circumstances, neoadjuvant therapy is generally recommended before surgical resection is undertaken. The usefulness of PET scans for pretreatment staging of the mediastinum is limited by a high rate of false positives. Moreover, the absence of abnormal hypermetabolism in mediastinal lymph nodes does not exclude the possibility of microscopic lymph node involvement. In recent years, transbronchial needle aspiration (TBNA) under EBUS guidance (EBUS-TBNA) of mediastinal lymph nodes has been utilized with increasing frequency. The positive predictive value of this method is practically 100%, but the negative predictive value is variable. To date, mediastinoscopy remains the most reliable method for excluding mediastinal lymph node involvement with metastatic tumor. With the advent of the videomediastinoscope, this procedure can now be done under video guidance. Although some believe that this is superior to standard mediastinoscopy, the most important contribution of this technique is the opportunity to teach a very dangerous and complex procedure without the surgeon “having to take their eye off” the field.
Technique
With the patient in the supine position under general endotracheal anesthesia, the endotracheal tube is carefully secured with adhesive tape at the left side of the mouth. The patient is positioned at the extreme head of the operating table, and the neck is hyperextended by placing a roll under the shoulders. A pillow is placed under the knees, and safety straps are securely fastened above and below the patellae. The operating table is turned so that the anesthesiologist is at the patient’s left side while the surgeon stands at the head. The anterior cervical and pectoral regions are prepared and draped.
A 2-cm horizontal incision is made in the suprasternal notch, below the thyroid isthmus and above the innominate artery, at a level where the trachea is most readily palpable. Ideally the incision can be hidden in a prominent skin crease. The incision is deepened through the platysma muscle. Anterior jugular veins may be ligated and divided. The strap muscles are separated in the midline with electrocautery. The pretracheal fascia is incised transversely with scissors. Blunt digital dissection is used to develop a pretracheal plane inferiorly.
The mediastinoscope is introduced into the pretracheal space, and additional blunt dissection is carried out with the insulated suction cautery to expose the anterior walls of the mainstem bronchi and the anterior aspect of the subcarinal space. A bronchial artery is usually seen coursing anterior to the proximal left mainstem bronchus into the subcarinal space. Before dividing this vessel with electrocautery, consideration should be given to ligating it using a short 5-mm endoscopic clip applier.
The subcarinal lymph node “packet” is dissected bluntly from the medial wall of the left mainstem bronchus and is reflected off of the anterior esophageal wall. Next, the subcarinal lymph node packet is dissected bluntly from the medial wall of the right mainstem bronchus. Electrocautery may be used to control the many bronchial vessels typically found in the subcarinal space. Care should be taken to avoid injury to the anterior esophageal wall and the posterior pericardium. Finally, the subcarinal lymph node packet is completely removed using biopsy forceps. Hemostasis is completed using electrocautery, and may be facilitated by epinephrine-soaked gauze packing.
Attention is turned to the paratracheal lymph nodes on the side contralateral to the primary lung tumor. Paratracheal lymph nodes are bluntly dissected, commencing inferiorly and proceeding cephalad. After the paratracheal nodes are completely dissected and excised from the contralateral side, attention is turned to the side ipsilateral to the primary tumor. Dissection of the right paratracheal nodes should include a careful search for lower pretracheal (station 3A) nodes. These nodes are typically found anteriorly, just medial to the right lower paratracheal (station 4R) nodes, and are dissected bluntly off the posterior pericardium.
On the right side, special care should be taken to avoid injury to the azygos vein and superior vena cava. The left recurrent laryngeal nerve courses especially close to the left lower paratracheal nodes. More distal dissection in the paratracheal space leads to the superior branches of the pulmonary artery. Using patient and gentle blunt dissection while minimizing the use of electrocautery, it is usually possible to mobilize intact lymph nodes almost completely before they are biopsied. In this manner, bleeding and recurrent laryngeal nerve injury can usually be avoided.
Hemostasis is completed with judicious use of electrocautery, aided by epinephrine-soaked gauze packing. A careful account is made of all packing as it is removed. With good hemostasis in effect, the mediastinoscope is removed and the incision is closed in layers. The strap muscles may be approximated using a single interrupted absorbable suture. The platysma muscle is reconstituted using a running absorbable suture. The skin is closed using a running subcuticular absorbable suture. Steristrips may be used and a Band-Aid is applied.
Mediastinoscopy
In the presence of mediastinal lymph node involvement, it is unlikely that non–small cell lung cancer can be cured by surgical resection alone. In such circumstances, neoadjuvant therapy is generally recommended before surgical resection is undertaken. The usefulness of PET scans for pretreatment staging of the mediastinum is limited by a high rate of false positives. Moreover, the absence of abnormal hypermetabolism in mediastinal lymph nodes does not exclude the possibility of microscopic lymph node involvement. In recent years, transbronchial needle aspiration (TBNA) under EBUS guidance (EBUS-TBNA) of mediastinal lymph nodes has been utilized with increasing frequency. The positive predictive value of this method is practically 100%, but the negative predictive value is variable. To date, mediastinoscopy remains the most reliable method for excluding mediastinal lymph node involvement with metastatic tumor. With the advent of the videomediastinoscope, this procedure can now be done under video guidance. Although some believe that this is superior to standard mediastinoscopy, the most important contribution of this technique is the opportunity to teach a very dangerous and complex procedure without the surgeon “having to take their eye off” the field.
Technique
With the patient in the supine position under general endotracheal anesthesia, the endotracheal tube is carefully secured with adhesive tape at the left side of the mouth. The patient is positioned at the extreme head of the operating table, and the neck is hyperextended by placing a roll under the shoulders. A pillow is placed under the knees, and safety straps are securely fastened above and below the patellae. The operating table is turned so that the anesthesiologist is at the patient’s left side while the surgeon stands at the head. The anterior cervical and pectoral regions are prepared and draped.
A 2-cm horizontal incision is made in the suprasternal notch, below the thyroid isthmus and above the innominate artery, at a level where the trachea is most readily palpable. Ideally the incision can be hidden in a prominent skin crease. The incision is deepened through the platysma muscle. Anterior jugular veins may be ligated and divided. The strap muscles are separated in the midline with electrocautery. The pretracheal fascia is incised transversely with scissors. Blunt digital dissection is used to develop a pretracheal plane inferiorly.
The mediastinoscope is introduced into the pretracheal space, and additional blunt dissection is carried out with the insulated suction cautery to expose the anterior walls of the mainstem bronchi and the anterior aspect of the subcarinal space. A bronchial artery is usually seen coursing anterior to the proximal left mainstem bronchus into the subcarinal space. Before dividing this vessel with electrocautery, consideration should be given to ligating it using a short 5-mm endoscopic clip applier.
The subcarinal lymph node “packet” is dissected bluntly from the medial wall of the left mainstem bronchus and is reflected off of the anterior esophageal wall. Next, the subcarinal lymph node packet is dissected bluntly from the medial wall of the right mainstem bronchus. Electrocautery may be used to control the many bronchial vessels typically found in the subcarinal space. Care should be taken to avoid injury to the anterior esophageal wall and the posterior pericardium. Finally, the subcarinal lymph node packet is completely removed using biopsy forceps. Hemostasis is completed using electrocautery, and may be facilitated by epinephrine-soaked gauze packing.
Attention is turned to the paratracheal lymph nodes on the side contralateral to the primary lung tumor. Paratracheal lymph nodes are bluntly dissected, commencing inferiorly and proceeding cephalad. After the paratracheal nodes are completely dissected and excised from the contralateral side, attention is turned to the side ipsilateral to the primary tumor. Dissection of the right paratracheal nodes should include a careful search for lower pretracheal (station 3A) nodes. These nodes are typically found anteriorly, just medial to the right lower paratracheal (station 4R) nodes, and are dissected bluntly off the posterior pericardium.
On the right side, special care should be taken to avoid injury to the azygos vein and superior vena cava. The left recurrent laryngeal nerve courses especially close to the left lower paratracheal nodes. More distal dissection in the paratracheal space leads to the superior branches of the pulmonary artery. Using patient and gentle blunt dissection while minimizing the use of electrocautery, it is usually possible to mobilize intact lymph nodes almost completely before they are biopsied. In this manner, bleeding and recurrent laryngeal nerve injury can usually be avoided.
Hemostasis is completed with judicious use of electrocautery, aided by epinephrine-soaked gauze packing. A careful account is made of all packing as it is removed. With good hemostasis in effect, the mediastinoscope is removed and the incision is closed in layers. The strap muscles may be approximated using a single interrupted absorbable suture. The platysma muscle is reconstituted using a running absorbable suture. The skin is closed using a running subcuticular absorbable suture. Steristrips may be used and a Band-Aid is applied.
Redo mediastinoscopy
When the spread of non–small cell lung cancer is limited to the mediastinal lymph nodes, neoadjuvant chemotherapy or concurrent chemoradiotherapy has been used successfully to downstage the disease, making it amenable to cure with surgical resection. The persistence of mediastinal lymph node involvement following neoadjuvant therapy is predictive of a low likelihood of cure with surgical resection. Typically the presence of mediastinal lymph node involvement is initially determined by pretreatment mediastinoscopy.
Following neoadjuvant therapy, restaging the mediastinum can be challenging. It is often unclear whether residual hypermetabolism in mediastinal lymph nodes is caused by inflammation resulting from neoadjuvant therapy, or is due to persistent mediastinal lymph node involvement with tumor. Even in cases where previously involved mediastinal lymph nodes are no longer hypermetabolic, the presence of residual microscopic involvement must be suspected. To avoid futile high-risk lung resection, reliable exclusion of persistent mediastinal lymph node involvement is essential.
In some cases, EBUS-TBNA of enlarged, hypermetabolic mediastinal lymph nodes can successfully identify persistent involvement with metastatic tumor. However, when posttreatment EBUS-TBNA is negative or equivocal in the face of enlarged or hypermetabolic lymph nodes, larger mediastinal lymph node biopsies might be desirable. In certain cases, redo mediastinoscopy might be the preferred approach to obtain these biopsies.
Due to the presence of dense fibrosis resulting from the initial mediastinoscopy and from neoadjuvant radiotherapy, performing a redo mediastinoscopy can be daunting. Concerns have been raised about the increased risk of recurrent laryngeal nerve injury and major venous or pulmonary arterial injury, as well as the inability to successfully reach all of the relevant mediastinal lymph node stations. Refuting such concerns, several investigators have published case series suggesting that redo mediastinoscopy can be performed safely and can effectively predict the presence or absence of persistent mediastinal lymph node involvement. The need for redo mediastinoscopy can be avoided if pretreatment mediastinal lymph node involvement is demonstrated by EBUS-TBNA; mediastinoscopy can then be reserved for posttreatment restaging.
Technique
Although the technique of redo mediastinoscopy is similar in most respects to the technique of initial mediastinoscopy, there are several special considerations that must be taken into account. The presence of dense fibrosis can make it difficult to gain access to the pretracheal space from the neck after prior mediastinoscopy. It may be more likely that anterior jugular veins will have to be divided. Strap muscles themselves might have to be divided. Dissection should be conducted directly on the anterior tracheal wall so as to avoid major vascular injury. Electrocautery should be used with great caution. Ultimately, it is usually possible to gain access to the pretracheal space and the subcarinal space below.
After reaching the subcarinal space, great care should be taken in dissecting the paratracheal spaces on either side. On the right side, injury to the azygos arch or superior vena cava is to be avoided. On the left side, recurrent laryngeal nerve injury is to be avoided. Lymph nodes are often more adherent than at initial mediastinoscopy; it is often wiser to biopsy only portions of lymph nodes rather than to attempt excisional biopsy of entire nodes. In any case, the key to making safe progress is patience and persistence.
Related posts:
Screening for Lung Cancer: Challenges for the Thoracic Surgeon
Epidemiology of Lung Cancer: Smoking, Secondhand Smoke, and Genetics
The Changing Pathology of Lung Cancer
The Surgical Management of Stage I and Stage II Lung Cancer
Role of Surgery Following Induction Therapy for Stage III Non–Small Cell Lung Cancer
Extensive Resections: Pancoast Tumors, Chest Wall Resections, En Bloc Vascular Resections
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
