Chapter 93: Innovative Radiation Techniques: Role of Brachytherapy and Intraoperative Radiotherapy in Treatment of Lung Cancer

INTRODUCTION

Brachytherapy, involving the use of radioactive isotopes placed directly on the desired target tissues during surgery or placed endoluminally, can be used for the treatment of lung cancer. It offers several theoretical advantages compared with traditional radiotherapy. Direct surgical placement of the radiation source allows for specific targeting and uniform delivery of the radiation, minimizing the amount of normal lung in the radiation field. Its potential advantage over external beam radiation therapy is that it limits the radiation dose to normal tissues and decreases the radiation side effects while providing a high dose of radiation directly to the targeted area, possibly improving tumor control.

EARLY-STAGE LUNG CANCER

It has long been established that lobectomy offers the best chance of cure for early-stage non–small-cell lung cancer (NSCLC). According to the Lung Cancer Study Group, sublobar or wedge resection is not as effective as lobectomy or pneumonectomy because it is associated with a high incidence of local recurrence.^1,2 However, a large resection requires the patient to have a reasonable residual forced expiratory volume in 1 second (FEV₁) of 0.8 to 1.2 L and a ventilation–perfusion scan corresponding to adequate breathing in other lung segments. Patients who have long histories of smoking commonly fail to demonstrate these advantageous characteristics. Techniques that combine sublobar resection with radiotherapy delivered intraoperatively or through the implantation of radioactive iodine (¹²⁵I) seeds at the lung resection margin have shown promising results (see Planar Seed Experience, below). This procedure has been reported to reduce local disease recurrence and improve the palliation of symptoms. Additionally, it provides a treatment option for patients who are physically incapable of undergoing lobectomy or pneumonectomy or who are considered high-risk surgical candidates consequent to other comorbidities.

Various systems for radiation delivery are used in clinical practice. Three techniques have been described following sublobar resection, all of which are compatible with thoracoscopy.

PLANAR SEED IMPLANT TECHNIQUE

There are several reports of wedge resection procedures for stage I tumors that have been performed in conjunction with planar ¹²⁵I seed implants. This procedure has been reported to reduce local disease recurrence and improve local control.

After the wedge resection, the surgeon determines the dimension of the implant by measuring the length and width of the area at risk. The implant is made of two components. The source material, called the Seed-in-Carrier, available through Oncura (Plymouth Meeting, PA), consists of ¹²⁵I seeds that are embedded in strands of absorbable Vicryl suture. A second isotope, ¹³¹Cs, is commercially available from Isoray Medical (Richland, WA). Each strand has 10 seeds, and each seed and strand is spaced 1 cm apart center to center. The individual seed measures 0.7 × 4 mm. The source material is attached to an absorbable mesh material made of either Dacron or Vicryl that is ...