Extended Resections for Lung Cancer: Chest Wall and Pancoast Tumors

General Principles

Invasion of the parietal pleura or chest wall by a primary lung cancer is a relatively rare occurrence, reported in 5% to 8% of all cases of lung cancer. Invasion of the parietal pleura and the chest wall suggests a T3 tumor, and involvement of the vertebral bodies suggests a T4 tumor. Tumors infiltrating the second or first rib and surrounding structures usually are considered to be superior sulcus or Pancoast tumors when neurologic symptoms are present. Pancoast tumors are described in detail in the latter part of this chapter.

Extensive resection is required to remove tumors invading the chest wall. Although such tumors once were considered to have a dismal prognosis, many series have shown that long-term survival may be possible when the patient has no distant metastases, no involvement of mediastinal nodes, and evidence of complete (R0) resection as demonstrated by histologically negative margins in the ribs as well as in the muscles and soft tissues of the chest wall. In addition, a thorough lymph node evaluation by means of either systematic node dissection or at least a lobe-specific node dissection related to the location of the primary tumor is required. A minimum of six lymph node stations must be removed, of which three must be located in the mediastinum and must include the subcarinal station. According to the definition of complete resection as proposed by Rami-Porta et al. there must be no extracapsular extension and the highest mediastinal lymph node must be negative. Complete (R0) resection can be challenging in cases of posterior tumors located near the costovertebral angle or involving vertebral bodies, and analysis of frozen sections is not feasible for tumors with osseous margins.

Staging

The goal of surgical treatment in cases of T3 and T4 lung cancers is to obtain an R0 resection. Surgical treatment may be part of a multimodality approach that includes induction chemotherapy or chemoradiation therapy to reduce the tumor volume and to optimize resection margins. A thorough preoperative evaluation is necessary. Functional operability depends on a detailed cardiopulmonary assessment as outlined by a working group of the ERS together with the ESTS. T3 and T4 tumors require at least a lobectomy, but no specific criteria have been developed to determine whether a patient will tolerate a planned chest wall resection. Nevertheless, as it is clear that a chest wall resection may induce additional respiratory compromise, clinical judgment by an experienced thoracic surgeon and discussion of each individual case by a multidisciplinary tumor board are necessary when this procedure is anticipated. Published series report that mediastinal nodal involvement is a poor prognostic factor and that extensive surgery is not warranted when mediastinal lymph node metastases are present.

Computed tomography (CT) of the chest with use of intravenous contrast medium is the preferred method for defining the extent of the primary tumor and evaluating the involvement of hilar and mediastinal lymph nodes ( Fig. 30.1 ). Findings on CT images that are used to identify osseous or soft-tissue chest wall invasion include obliteration of the extrapleural fat plane, the length of tumor contact with the pleural surface, the angle of the tumor with the pleura, and clear evidence of chest wall invasion. A combination of several criteria increases sensitivity. For paravertebral and superior sulcus tumors, magnetic resonance imaging (MRI) of the chest is required to determine neural or vertebral involvement. Respiratory dynamic MRI has been shown to have a sensitivity of 100% and a specificity of 83% for determining chest wall invasion but has not been widely adopted. Ultrasonography of the chest wall also may be helpful but does not show superior sulcus tumors. Positron emission tomography (PET), preferably, integrated PET–CT, should be performed for every patient to evaluate local–regional extension and possible distant spread precluding surgical intervention.

The pathologic status of the mediastinal nodes should be confirmed before a large chest wall resection is planned. Endobronchial ultrasound and endoscopic ultrasound with transbronchial or transesophageal biopsy are currently the procedures of choice. In selected cases, these procedures are supplemented with mediastinoscopy to reduce the false-negative rate as much as possible.

Surgical Resection

Depending on the location of the primary tumor and its extension into the chest wall, the incision is carefully chosen and may be centered on the anterior, lateral, or posterior chest wall. The thoracic cavity is entered away from the primary tumor, as every attempt should be made to obtain an en bloc resection with complete removal of the primary tumor together with the invaded chest wall to avoid any spillage of tumor cells in the pleural cavity. Video-assisted thoracoscopic surgery may be helpful for initial evaluation.

The precise margins to be obtained around the primary tumor have not been exactly determined, but most authors have agreed that at least 1 cm is required. Once the pleural space has been entered, chest wall involvement is evaluated and a determination is made as to whether an extrapleural resection or a full-thickness chest wall resection is required. Stoelben and Ludwig described four categories of chest wall involvement for determining the subsequent resection ( Table 30.1 ). When the tumor easily detaches from the chest wall in the extrapleural plane by finger dissection, this usually indicates only inflammatory adhesions that do not require chest wall resection. Frozen section analysis of suspicious areas of the parietal pleura may clarify this. When the tumor is densely adherent or frankly invades the chest wall, rib resection is indicated. For anterior tumors, resection of part or all of the sternum may be needed. For posterior tumors, resection of transverse processes or vertebral bodies may be needed, and a spine surgeon (either an orthopedic surgeon or a neurosurgeon) should work collaboratively with the thoracic surgeon. However, resection of these vertebral structures is infrequently seen outside the classic Pancoast (superior sulcus) position. To reduce trauma to the uninvolved extrathoracic muscles, rib resection can be performed from inside the chest with use of the technique described by Cerfolio et al.

Lobectomy or bilobectomy is the procedure of choice for pulmonary resection. A pneumonectomy is necessary in some cases, but it is a high-risk procedure when combined with extensive chest wall resection and should be performed only in centers with extensive experience.

Multiple techniques are available for reconstruction of the chest wall. No reconstruction is required for defects of 3 cm or less that are covered by the scapula. However, when the defect is located at the tip of the scapula, chest wall reconstruction is required to prevent entrapment of the scapula, which is a highly symptomatic complication that is associated with poor cosmetic results. Polypropylene and polyglactin meshes, polytetrafluoroethylene patches, and the so-called Marlex mesh with methylmethacrylate (MMM) sandwich technique are options for the reconstruction of large defects. Close cooperation with a plastic surgeon is required in situations in which soft-tissue reconstruction is needed to cover a chest wall prosthesis. Polytetrafluoroethylene is frequently used as the standard material. However, for large anterior or anterolateral defects, the MMM sandwich technique provides greater immediate chest wall stability ( Figs. 30.2A and 30.2B ) with the lowest risk of postoperative respiratory insufficiency. A new moldable system composed of titanium with connecting bars and rib clips is useful for obtaining a rigid basis when reconstructing the chest wall. This system is particularly useful for large defects associated with skin ulceration and infection, for which the MMM sandwich technique is contraindicated ( Fig. 30.3A–B ). Synthetic material should be covered by viable muscle or musculocutaneous flaps to reduce the risk of infection.