Pancoast Tumors





Surgical Anatomy





  • A Pancoast tumor is a lung cancer arising in the apex of the lung that involves structures of the apical chest wall. In contrast to the original definition, involvement of the brachial plexus and the stellate ganglion is no longer absolutely required. This change has come from a more detailed understanding of the structures of the thoracic inlet, which is divided into several compartments ( Table 12-1 , Fig. 12-1 ). The many important structures coursing through this area makes the anatomy of this area complex ( Fig. 12-2 ). Surgery for Pancoast tumors also requires a clear understanding of the posterior ribs and spine ( Fig. 12-3 ).



    Table 12-1

    Compartments of the Thoracic Inlet




















    Compartment Boundaries (Along First Rib) Included Structures
    Anterior Sternum to anterior edge of anterior scalene muscle Sternocleidomastoid and omohyoid muscles, jugular and subclavian veins and branches
    Middle Anterior scalene muscle up to posterior border of middle scalene muscle Anterior and middle scalene muscles, subclavian artery and branches, phrenic nerve, trunks of brachial plexus
    Posterior Behind middle scalene muscle Posterior scalene muscle, posterior scapular artery, nerve roots of brachial plexus, long thoracic, spinal accessory nerves, sympathetic chain, stellate ganglion, neural foramina, vertebral bodies

    From Detterbeck FC. Changes in the treatment of Pancoast tumors. Ann Thorac Surg 2003;75:1900-1907.



    Figure 12-1



    Figure 12-2



    Figure 12-3






Preoperative Considerations





  • There are so many different approaches to Pancoast tumors that choosing an incision is confusing. The traditional high posterolateral thoracotomy has some advantages but provides limited access to many structures of the thoracic inlet. Many variations of anterior approaches have been described. The incision in the neck can be either along the anterior border of the sternocleidomastoid muscle (SCM) or just above the clavicle. The incision continues down the midline and then extends laterally just below the clavicle with removal of the clavicle, into the first intercostal space (ICS), the second ICS, the fourth ICS, or hemiclamshell, or simply into a full sternotomy. Furthermore, although it is ideal for a complete resection to be accomplished through one incision, one should not hesitate to use a combined anterior-posterior approach or an additional thoracotomy.



  • The choice of incision is dictated by the characteristics of the tumor, which vary from patient to patient. The tumor location and resulting anatomic issues can be divided into several major categories, as described in this chapter.




Resection of the Anterior Chest Wall


Definition





  • Tumors involving the anterior first rib from the manubrium up to and including insertion of the anterior scalene muscle



Recommended Incision





  • Midline division of the manubrium is done with a lateral extension into the ICS below the tumor. The neck incision is generally made along the anterior border of the SCM because exposure of more lateral structures (i.e., the middle portion of the thoracic inlet) is not needed. The midline manubrial incision is useful because exposure of the innominate vein is usually required. The lateral extension of the incision allows lateral division of ribs and control of the axillary vessels for tumor resection together with the subclavian vein (or artery).




Access to Midline Structures


Definition





  • Tumors involving a vertebral body, involving nerve roots as they exit the neural foramina, or requiring control of the innominate artery or vein



Recommended Incision





  • Midline division of the manubrium, usually combined with an incision along the anterior border of the SCM, is recommended. (Alternatively, access to the innominate artery and vein can be achieved after resection of the clavicle and resection of the first rib starting right at the edge of the manubrium.)




Access to Lateral Structures


Definition





  • Tumor involving the middle portion of thoracic inlet, lateral brachial plexus, lateral subclavian artery or vein



Recommended Incision





  • Supraclavicular incision and partial sternotomy are recommended. (Alternatively, an incision along the anterior border of SCM extending to an infraclavicular incision with removal of the medial half of the clavicle can be used.)




Invasion of Posterior Chest Wall/Neural Foramina


Definition





  • Tumor growing adjacent to or through the neural foramina



Recommended Incision





  • Posterior approach, for example, a simple posterolateral (Shaw-Paulson) approach (either alone or a combined posterior and anterior approach)




Extensive Hilar Involvement


Definition





  • Tumor extension to hilum or hilar node involvement (e.g., requiring a sleeve lobectomy)



Recommended Incision





  • Midline division of the sternum, either with a lateral incision into the fourth ICS or a full sternotomy, is recommended. (Alternatively, a thoracotomy can be performed as a separate incision.)






Operative Steps



Anterior Chest Wall Involvement


Superficial Structures





  • An incision is made along the anterior border of the SCM (or modified with a supraclavicular incision) ( Fig. 12-4 ).




    Figure 12-4



  • Attachment of strap muscles is divided (with or without omohyoid).



  • Midline partial sternotomy is made through the manubrium.



  • L -shaped extension is made into the second ICS (level modified as needed).



  • Sternal attachments of the pectoralis major muscle are detached.



  • Most of the pectoralis major muscle attachment to the clavicle is preserved.



  • Pectoralis major muscle is divided between fibers.



  • Internal mammary artery/vein (IMA/V) is divided (rarely, the proximal portion is dissected free and preserved).



Mobilization of Bony Parts





  • Costal cartilage of involved ribs is divided (see Fig. 12-4 , inset).



  • Manubrium/clavicle is raised by progressive dissection of ligamentous and muscular (subclavius) attachments on the undersurface of the clavicle.



  • Axillary vessels are dissected free as they exit under the clavicle.



  • After mobilization of manubrium/clavicle, the anterior scalene muscle is detached from the first rib (as needed).



  • Lateral division of ribs is performed underneath mobilized pectoralis major/minor muscle (or through a small axillary incision as needed).



Deeper Dissection



Mar 13, 2019 | Posted by in CARDIOLOGY | Comments Off on Pancoast Tumors
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