Lung cancer is the leading cause of cancer deaths worldwide, and surgical resection remains the treatment of choice for early-stage lung cancer. Invasion of the superior vena cava (SVC) by lung cancer has long been considered a contraindication to surgery. In the past, this group of patients was classified as stage IIIB with a 5-year survival rate of 8%. The results reported in the literature over the past 30 years suggest that this concept may need to be updated. The 5-year survival rate for lung cancer patients undergoing SVC resection and reconstruction can be as high as 30%. The latest version of the TNM staging system takes this into account and classifies T4N0-1M0 tumors as stage IIIA.
Forms of superior vena cava involvement include direct invasion of the SVC opening by a central tumor (T4) or metastatic lymph node invasion (N2). In addition, separation or adhesions to mediastinal structures may occur. Patients may present with SVC obstruction syndrome. To provide clinicians with a better understanding of the treatment and prognosis of lung cancer invasion of the superior vena cava, Professor Lee et al. authored a review that was published in a recent issue of Thorac Surg Clin.
Preoperative assessment.
A comprehensive preoperative assessment of the patient for indication for surgery. Diagnose for N2 by imaging techniques or biopsy. exclude patients with distant metastases. Preoperative pulmonary function tests should be performed, as total pneumonectomy may be required intraoperatively. In addition, complete resection of SVC often requires sacrifice of the phrenic nerve. Therefore, bilateral phrenic nerve involvement is a contraindication to surgery.
Treatment options.
The choice of surgical approach is based on the surgeon’s preference. Most can be performed through a standard postero-lateral opening, but other approaches can be included, including median opening, semi-clamshell incision, transcervical sternal splitting pathway, combined neck dissection, and open thoracotomy. Large-bore venous access to the lower extremity is required to ensure maintenance of blood volume during SVC clamping.
Reconstruction of the superior vena cava resection can be accomplished by partial or complete resection. When the tumor invades a small portion of the SVC, it can be resected in its entirety after controlling the vessel by local blocking forceps. Depending on the size of the vascular defect, one-stage suturing or patch repair with an autologous pericardial prosthesis may be attempted.
This technique avoids the potential risk of infection following exogenous prosthetic grafts. Prosthetic grafts are necessary if the diameter of the SVC to be resected is more than 50%.
In complete resection, the SVC needs to be completely clamped to the vessel to control bleeding. The SVC should be clamped over the odd vein to preserve some blood flow to prevent cerebral hypoxia. However, if tumor anatomy is deemed infeasible, the SVC can be clamped for prolonged periods of time, up to 60mins in experimental animal models.
Hemodynamic sequelae after clamping are rare in patients with chronic SVC syndrome. However, acute occlusion of SVC by clamping can induce a variety of adverse hemodynamic responses. Decreased right ventricular preload can lead to decreased cardiac output and systemic hypotension.
In addition, increased venous pressure increases the risk of intracranial thrombosis and edema, which can lead to irreversible brain damage. Therefore, given these potential hemodynamic effects, patients with acute SVC obstruction should not undergo urgent SVC resection. These hemodynamic effects are usually self-limiting and can be reduced intraoperatively by intravascular fluid dilation and vasoconstrictors.
Complete SVC resection and reconstruction can be performed with in situ grafting, circumferential polytetrafluoroethylene grafting, or pericardial tubular shunts with or without combined vena cava shunts.
For tumors that invade the proximal and right innominate veins, the graft should connect the right atrium to the left innominate vein, followed by excision of the SVC.
Only one side of the innominate vein needs to be preserved, as the swelling of the unilateral arm improves with time after vessel transection.
Systemic heparinization is sometimes recommended, usually without extracorporeal circulation.
Postoperative complications.
Postoperative complication rates and mortality rates are as high as 40% and 14%, respectively, with the majority being respiratory complications.
The incidence of graft infection can be as high as 7%, second only to secondary pulmonary infectious complications (bronchopleural fistula, abscess chest and lung abscess).
Induction therapy is associated with an increased risk of postoperative complications. There was a trend toward an increased risk of death in patients undergoing total pneumonectomy, but there was no statistical difference.
Early graft thrombosis (within 1 month) was as high as 11%. Late graft thrombosis has been reported to be as high as 30%. The risk of thrombosis may be related to SVC stenosis, exogenous grafts or hemodynamic changes. Postoperative anticoagulation therapy with oral warfarin for 3-6 months is recommended.
Summary.
The median survival of patients with SVC resection and reconstruction of intermediate to advanced lung cancer is 8.5-40.0 months, with a 5-year survival rate of up to 30%.
N2 had a poorer prognosis compared to N0/N1 patients, but there was no statistical difference.
Patients with total pneumonectomy have a poorer prognosis.
Although induction therapy is associated with increased perioperative complications, it may also increase disease-free survival time.