Adult Chest Surgery

Chapter 77. Percutaneous Thoracic Tumor Ablation 

Thoracic surgeons and oncologists currently have a new tool in their oncologic armamentarium against focal lung cancer that is provided by the interventional radiologist—image-guided percutaneous radiofrequency ablation (RFA). The procedure is still relatively new and is yet to find its clear niche. Although the literature is sparse, the experience with RFA for tumors in other organs (e.g., liver, kidney, and bone) combined with early results of RFA for lung tumors heralds optimism, particularly for patients who are not surgical candidates.

This chapter describes the types of patients who may benefit from RFA, along with early results, risks, and complications. An overview of RFA techniques, mechanisms, and equipment is given. Finally, the varied expertise and respective roles of the multidisciplinary team are highlighted.

INDICATIONS

Currently, RFA is not a first-line form of therapy for either primary or secondary pulmonary tumors. RFA should be considered only if thoracic surgeons and oncologists, as well as radiation therapists, have exhausted more conventional options or determined that these traditional methods are not suitable.1–10 For example, patients who have undergone prior operations such that reoperation is not feasible, patients who have had maximal radiation or chemotherapy, and patients with severe respiratory compromise that preclude surgery are candidates for RFA.1,2 Patients with an inoperable tumor and refractory pain may have that pain ameliorated by RFA. Associated painful erosion of ribs or growth into portions of the mediastinum may be treated by RFA as well.1,2 As with hepatic tumors, a combined approach with surgical excision, segmentectomy, or lobectomy for one or more tumors, combined with RFA for other tumors in different lobes, may be performed; in the latter situation, intraoperative RFA can be an option.

Ablation may have either cure or cytoreductive palliation as the goal, each of which must be conveyed to patients, families, and referring physicians prior to RFA. Both primary bronchogenic carcinoma and metastatic7tumors can be treated. Various primary non-small cell carcinomas (NSCLC) and metastatic cell types have been treated. Smaller tumors are more likely to be cured. Since small cell lung carcinoma is a systemic disease, it usually is not an indication for local RFA, although rarely focal therapy may be used. Mesothelioma has been treated as well.2

WORKUP

Typically, once the clinical team of the thoracic surgeon, the oncologist, and the radiation therapist has opined that the patient may be a candidate for RFA, the patient is referred to the tumor ablation interventional radiology team. The radiologists will review the patient's relevant radiologic images (i.e., chest x-ray, CT scan, MRI, and CT/PET scan) to ascertain the size and extent of disease, extrathoracic lesions, number of tumors to potentially be treated, proximity of vital structures, and nonpulmonary tumors (rib, etc.) that also might benefit from RFA. If the ablation team concurs that the patient is an appropriate candidate, the patient and family have a consultation with the team. Discussion ensues about the benefits, risks, techniques, and results of the procedure; questions are answered; and signed informed consent is obtained.

Routine blood tests, including coagulation studies, are obtained. Prothrombin time within 3 seconds of control, an international normalized ratio (INR) of less than or equal to 1.5, a partial thromboplastin time in the low to middle 40-second range, and a platelet count of greater than 50,000/mL are considered acceptable. The patient undergoes consultation with an anesthesiologist for planned general anesthesia in the CT radiology suite. For patients with known or suspected respiratory compromise, the input of a specialized thoracic anesthesiologist is advisable, as well as preprocedure consultation with a pulmonologist to improve pulmonary function. Some radiologists prefer conscious sedation during RFA; in this situation, the anesthesiology step is bypassed.

PERIPROCEDURAL CARE: BEFORE AND AFTER ABLATION

Our preference is to perform all procedures under general anesthesia delivered by an anesthesiologist. This provides (1) continuous monitoring of vital signs—heart rate, electrocardiographic tracing, oxygen saturation, end-tidal carbon dioxide, temperature, and blood pressure; (2) ready assistance for the management of any cardiopulmonary emergency; and (3) reproducible breath holds (suspension of respiration) for needle placement during tumor targeting with the RFA electrodes. A double-lumen endotracheal tube may be placed at the discretion of the anesthesiologist. However, in our experience, these have rarely proved to be helpful or necessary. Oxygenation and ventilation in patients with significant pulmonary disease commonly are superior with single-lumen tubes. Some practitioners opt for monitored anesthesia (MAC) performed by an anesthesiologist or nurse-administered conscious (moderate) sedation; these two latter methods are advantageous timewise. In all cases, cefazolin sodium (Ancef) 1 g is administered intravenously before the procedure and for two additional doses after RFA.

In our practice, patients are admitted overnight for observation and are discharged the following morning if no complications arise. Most patients go home after the overnight stay; patients with chronic obstructive pulmonary disease may take longer to recover.Patients treated under MAC or conscious sedation may be discharged on the same day as the procedure.

RFA EQUIPMENT

RFA is performed by resistive heating of the tumor that is produced by a high electric current density delivered by a monopolar "active" electrode (also known as the probe, needle, or applicator). The electrode, which is placed interstitially within the tumor, is powered by an electrical generator that provides alternating current at a frequency of approximately 450 kHz in the radio region of the electromagnetic spectrum. The electric circuit is completed by the return of current via "dispersive" electrodes (grounding pads that are adhered to the patient's thighs). The grounding pads have a large surface for the return of the current without heating; they number from two to four depending on the manufacturer's instructions.

There are two categories of RFA electrodes, needle and array. Both are capable of elevating tissue temperatures to cytotoxic levels for effective ablation (Fig. 77-1). The devices currently available for use in the United States are the Cool-Tip System (Covidien, Mansfield, MA), the LeVeen Needle Electrode (Boston Scientific Corporation-Oncology, Natick, MA), and the Starburst Electrode (Angiodynamics, Queensbury, NY). For each device, the active electrodes are available in various sizes—the size of the active element can be selected to provide a volume of ablation that best matches the target.

Figure 77-1.

 
 
 

Electrodes used for RFA. A. Cluster probe (Covidien, Mansfield, MA). B. LeVeen umbrella probe (Boston Scientific Corporation-Oncology, Natick, MA). C. Starburst probe (AngioDynamics, Queensbury, NY).

The hallmark of the needle-type Covidien Cool-Tip system, as the name suggests, is its internal cooling system. The electrode is cooled by a peristaltic pump that contains continuously flowing chilled water. The water circulates in a closed loop and is not deposited into the tissue. The cooling prevents tissue charring adjacent to the electrode that could impede current flow into the tissues and limit the size of the ablated volume.

The Boston Scientific Corporation (LeVeen) and AngioDynamics (Starburst) electrodes are both of the array type. Each provides a cannula for insertion into the body. Once the cannula is situated within the tumor, individual fine electrodes (tines) are deployed and splay out into the tissue. The key characteristic of the Boston Scientific probe is that it monitors the resistance to the flow of electricity (impedance) in the tumor. When the impedance rises, the treatment is complete. The Starburst probe provides multiple discrete measurements of the temperature at each of several of its tines. The temperature thus can be monitored, and the ablation can be terminated after a prescribed temperature has been reached within the targeted tissues.

TREATMENT

The patient is brought to the CT suite and placed under general anesthesia by the anesthesiologist. With suitable positioning and stabilization, the first CT scans are acquired to localize the tumor and critical juxtaposed structures. Initially, a fine-needle biopsy is performed—if not obtained previously.11 We prefer to use 25-gauge needles.12 The biopsy is followed by placement of the RFA electrode into the lesion by the tandem technique alongside the fine needle. Once the probe is positioned properly, the guide needles are removed, and the radiofrequency energy is applied. Multiple overlapping "burns" can be applied to cover large tumors in a single session (Fig. 77-2).

Figure 77-2.

 
 

Large left upper lung sarcoma in a middle-aged woman. A. Coronal MRI demonstrates huge upper lung tumor pushing mediastinal structures contralaterally. B. Radiofrequency probe in the anterior aspect of the tumor, one of five ablation sites.

The total ablation volume is usually intended to incorporate the entire tumor as well as a 1-cm-wide ablation margin, akin to a tumor-free margin in a surgical resection.

IMAGING

Multimodality imaging is the hallmark of the radiologic workup for thoracic tumor RFA. Thus all patients will have a chest x-ray and a CT scan, and many will have an MRI scan, brain scan, and bone scan. Finally, a CT/PET study rapidly is becoming a valuable adjunct to the workup. Not infrequently, CT/PET will discover an abnormal area that was not recognized previously. The number of tumors, the size(s), the juxtaposed structures, possible direct extension of tumor, adenopathy, extrathoracic disease, and identification of major vessels all must be addressed meticulously to optimize the safety and efficacy of the procedure.

Intrapulmonary lesions typically show a surrounding "ground glass" appearance on chest x-ray or CT scan after RFA (Fig. 77-3). This effect is thought to be due to edema and blood. The RFA-induced effect on CT scan typically is larger than the lesion itself (Fig. 77-4). Small pleural effusions are common. Postprocedure cavitation is common (Fig. 77-5). Over time, lesions shrink; the time course may be over several years.13

Figure 77-3.

 
 

RFA of solitary lung mass in a patient who refused surgery. A. Preprocedural contrast-enhanced supine CT scan of primary bronchogenic carcinoma in right lower lobe in a 59-year-old woman shows inhomogeneous enhancement of the lesion (arrow). B. Contrast-enhanced prone CT scan immediately after RFA shows no enhancement in the ablated lesion (arrow).

 

Figure 77-4.

 

RFA near the heart. This 79-year-old man had a solitary prostate metastasis near the heart. Supine contrast-enhanced CT scan immediately after ablation shows radiofrequency probe (arrows) in tumor approximately 1 cm from heart. Patient suffered no adverse effects and had complete necrosis of the tumor.

 

Figure 77-5.

 
 
 
 

A 34-year-old woman with metastatic adenoid cystic carcinoma. A. Postcontrast T1-weighted MRI image shows enhancing 1.2-cm right middle lobe nodule. B. Day 1 after ablation, the necrotic tumor is nonenhancing with surrounding edema and reactive tissue. C, D. FDG CT/PET scans at 6 months shows cavitary rim and minimal metabolic activity.

Typically, once the procedure is concluded, the patient undergoes CT scan and/or MRI within a day to ascertain the initial efficacy of the RFA. IV contrast medium is used before the procedure to assess adjacent vessels and tumor enhancement and after the procedure primarily to assess enhancement (or lack thereof) and to detect complications. Contrast medium is used intraprocedurally only in patients in whom vessel-tumor delineation is an issue. Marked reduction in Hounsfield units in the tumor by CT scan, by so-called CT densitometry, has been used as a sign of successful RFA.9

Patients are followed every 3 months for 1 year after RFA with one or a combination of at least one of the following studies: CT, CT/PET, or MRI. Growth of a tumor, nodularity, or enhancement with IV contrast material signifies recurrence. [18F] fluorodeoxyglucose (FDG) uptake that is avidly hypermetabolic on CT/PET signifies tumor persistence or regrowth.14 If there is no recurrence after 1 year, imaging is performed every 6 months or so. If a new lesion, recurrence, or persistent of tumor is found on imaging at any time, reevaluation of the patient is performed by the multidisciplinary team; if indicated, RFA may be repeated.

POSTPROCEDURE AND FOLLOW-UP

Once the procedure is completed to the satisfaction of both the radiology and anesthesiology teams, the patient is extubated and transferred to the recovery room. In the recovery room, the patient is treated as a postoperative patient and is visited by the interventional radiology ablation team. When the anesthesiologist has determined that the patient has recovered adequately from the general anesthesia, the patient is transferred to a floor for overnight observation.

In our institution, the patient is admitted to the Thoracic Surgery Service and to the surgeon who evaluated the patient initially and recommended or concurred with RFA. The patient is managed as any other postoperative patient, with care for vital signs, intake and output, wound care, and ambulation. If the patient had a small radiologic catheter (7F) inserted intraprocedurally for a pneumothorax, management is coordinated between the surgical and radiology ablation teams, although the radiologists manage their catheter, as with other interventional radiology procedures. The radiologist makes rounds daily and communicates directly with the surgical or referring team until discharge. The patient is given instructions prior to discharge and told to call the radiology group if a problem develops.

Within a week, the patient returns to the hospital from home to see both the interventional radiology ablation team and the admitting surgeon or the other referring physician. Follow-up visits to the surgeon and oncologist also are scheduled.

RFA, like surgery and radiation therapy, is a local therapy. Recurrences can be either local or systemic. In general, systemic recurrences require systemic therapy, either chemotherapy or hormonal therapy. Local recurrences, or isolated recurrences, are amenable to additional local therapies, including repeat RFA. Once a recurrence has been recognized, an aggressive search for the full extent of recurrence with the assistance of a PET scan and brain scan is indicated prior to the recommendation of salvage therapy.

RESULTS

Since the initial report of three patients,15 in 2000, several, but not numerous, papers have reported reasonable success in tumor destruction of primary and secondary thoracic malignancies2–4,9,15–17 (Table 77-1). Various metrics for successful ablation have been used—technical, percentage of necrosis, tumor size, CT densitometry, and clinical follow-up, including survival. Pain reduction or elimination from the tumor or adjacent growth also has been achieved with RFA (Fig. 77-6).2

Table 77-1. Published Literature on RFA for Lung Tumors

Author/Journal/Year

No. of Pts

Primary vs. Metastatic Tumor

Results (Success %)

Major Complications (%)

Lencioni/CVIR/2004

71

Both

90

?

vanSonnenberg/AJR/2005

30

Both

86.7

16

Lee/Radiology/2004

30

Both

38 (cure)

10

Steinke/JCAT/2003

20

Metastatic

?

25

Gadaleta/AJR/2004

18

Both

94.4

<10

Fernando/JTCVS/2005

18

Primary

83.3

44

Suh/Radiology/2003

12

Both

60

<10

Dupuy/AJR/2000

3

Both

100

33

 

Figure 77-6.

 
 

A 55-year-old man with extension of bronchogenic carcinoma into the pleura. A. Radiofrequency probe (arrows) has been inserted into malignant pleural tissue for ablation. B. Active portion of probe (arrows) has been pulled back into eroded portion of adjacent rib that was causing patient's pain. Within several days, the pain abated completely.

ABLATION OF METASTATIC SITES

While this chapter focuses on intrathoracic primary and secondary malignancies in the lung, ablation can be performed in virtually all other body sites as well. Thus ablation of metastatic disease from primary lung tumors has been accomplished in osseous sites, adrenal glands, and liver deposits. Pain is an important indication for these ablations; relief of pain symptoms in visceral organs and soft tissues has been achieved in 86% of patients after ablation.18 A valuable use of RFA or other methods of ablation is to palliate pain from direct extension of a pulmonary malignancy into the pleura, ribs, or chest wall (Fig. 77-7). Pain amelioration can be achieved by ablation of the soft tissue tumor, as well as directly into the bony metastasis.

Figure 77-7.

 

RFA for pain control. This 88-year-old woman with a 15-cm primary bronchogenic carcinoma was having intense chest wall pain from growth of tumor into soft tissues. On prone CT scan, the radiofrequency probe (arrows) is in the peripheral portion of tumor, where there has been direct extension into the chest wall. Four radiofrequency applications were performed in this session. Note gas (arrowhead) in the tumor, indicating necrosis. Patient's pain went from 10 to 3 (on a scale of 10) within 1 week.

COMPLICATIONS

The three common problems in the immediate posttreatment course include pneumothorax, pleuritic pain, and hemoptysis. Pneumothoraces are treated with a small-bore (6-8F) percutaneous locking catheter. Indications for catheter insertion include symptoms, pneumothorax greater than 33% and enlarging, and to continue the ablation procedure if the tumor has moved significantly from the original target localization on CT.2,17 One report described a 20% incidence of pneumothorax, and that two of three of those patients required a chest tube; another series had a 50% pneumothorax rate.10 Once a pneumothorax has developed, the anesthesiologist must be advised because pneumothoraces expand in the presence of nitrous oxide and possibly with positive-pressure ventilation. Pleuritic pain is common if the burn is adjacent to or involves the pleura and is managed with a combination of narcotics, acetaminophen, nonsteroidal therapy, and intercostal nerve blocks (performed by the radiologist at the time of the ablation).2

Major complications occur in fewer than 5-10% of patients. The spectrum of complications ranges from insignificant less than 10% pneumothorax or blood-tinged sputum to major bleeding and lung collapse necessitating chest tube insertion. Hemoptysis may not start until several days after the procedure. In general, it is streaky hemoptysis and is self-limited, clearing in a few days. Patients should be warned to expect this phenomenon. Massive hemoptysis (>200 mL) should not occur. Patients with massive hemoptysis should be evaluated in the hospital by the thoracic surgery and interventional radiology teams. Cases of major bleeding and even death have occurred.1,19

Unusual complications have included vocal cord injury with speech problems, a skin burn, and upper extremity weakness or pain owing to arm positioning.The postablation syndrome occurs in about 10–20% of patients undergoing ablation in any organ and is a flulike syndrome; its occurrence and severity likely are related to the volume of tumor that is killed and subsequent cytokine release. The syndrome is treated with fluids, acetaminophen, and supportive care. Typically, symptoms abate within 1–2 weeks.

The potential for ventilatory difficulty after general anesthesia and the need for protracted intubation exists, particularly with patients who have chronic obstrucive pulmonary disease. Avoiding a pneumothorax by modification of the salinoma technique to a "hydroma" is advisable,20 especially in markedly respiratory compromised patients. The hydroma technique pushes the lung away from the pathway of the probe by creating hydrodissection, with water, thereby avoiding pneumothorax; saline is not used because it may conduct the radiofrequency energy into undesirable locations.

Care must be emphasized with juxtacardiac lesions. If the radiofrequency probe or its tines touch the heart, animal experiments have shown a risk for ventricular fibrillation and death.21 Direct injury to the heart from the needle or probe can occur as well.

Careful attention to arm position under general anesthesia is important to avoid brachial plexus injury.22 This includes padding pressure points beneath the anesthetized patient and adequate adhesion of the grounding pads. Cardiac defibrillators should be available in the interventional suite where ablation is performed.

SUMMARY

RFA offers a new option for the care of patients with thoracic malignancies. Realistic expectations of cure versus palliation, the likelihood of recurrence or new tumor development, and the possibility of complications must be made clear to patients and families to have a realistic and proper perspective on this exciting but still evolving innovation. The ultimate role of RFA or any other form of percutaneous ablation method is yet to be defined clearly for thoracic tumors. Interaction of various specialties in the entire ablation process allows the expertise of each discipline to contribute clearly a salutary strategy for patient care.

ACKNOWLEDGMENTS

We wish to express our appreciation to Ms. Sandy Sharp for preparation of the manuscript, Mr. Bill McMullen for ablation project coordination, and Ms. Nicole McLavey for technical assistance.

EDITOR'S COMMENT

RFA is one technique that now can be used to manage a locally limited tumor in a high risk patient who is not a candidate for surgical resection. Stereotactic radiosurgery and brachytherapy are other local treatment options. Prospective randomized trials designed to compare these nonresectional modalities are needed.

–MJK

REFERENCES

1. Dupuy DE, Mayo-Smith WW, Abbott GF, DiPetrillo T: Clinical applications of radio-frequency tumor ablation in the thorax. Radiographics 22:S259–69, 2002. 

2. VanSonnenberg E, Shankar S, Morrison PR, et al: Radiofrequency ablation of thoracic lesions: 2. Initial clinical experience—Technical and multidisciplinary considerations in 30 patients. AJR 184:381–90, 2005. [PubMed: 15671350]

3. Lencioni R, Crocetti L, Cioni R, et al: Radiofrequency ablation of lung malignancies: Where do we stand? Cardiovasc Intervent Radiol 27:581–90, 2004. [PubMed: 15578133]

4. Gadaleta C, Mattioli V, Colucci G, et al: Radiofrequency ablation of 40 lung neoplasms: Preliminary results. AJR 183:361–8, 2004. [PubMed: 15269026]

5. Lee JM, Jin GY, Goldberg SN, et al: Percutaneous radiofrequency ablation for inoperable non-small cell lung cancer and metastases: Preliminary report. Radiology 230:125–34, 2004. [PubMed: 14645875]

6. Nishida T, Inoue K, Kawata Y, et al: Percutaneous radiofrequency ablation of lung neoplasms: A minimally invasive strategy for inoperable patients. J Am Coll Surg 195:426–30, 2002. [PubMed: 12229953]

7. Kim TS, Lim HK, Lee KS, et al: Imaging-guided percutaneous radiofrequency ablation of pulmonary metastatic nodules caused by hepatocellular carcinoma: Preliminary experience. AJR 181:491–4, 2003. [PubMed: 12876032]

8. Herrera LJ, Fernando HC, Perry Y, et al: Radiofrequency ablation of pulmonary malignant tumors in nonsurgical candidates. J Thorac Cardiovasc Surg 125:929–37, 2003. [PubMed: 12698158]

9. Suh RD, Wallace AB, Sheehan RE, et al: Unresectable pulmonary malignancies: CT-guided percutaneous radiofrequency ablation—Preliminary results. Radiology 229:821–9, 2003. [PubMed: 14657317]

10. Steinke K, King J, Glenn D, Morris DL: Radiologic appearance and complications of percutaneous computed tomography-guided radiofrequency-ablated pulmonary metastases from colorectal carcinoma. J Comput Assist Tomogr 27:750–7, 2003. [PubMed: 14501366]

11. Moreland WS, Zagoria RJ, Geisinger KR: Use of fine needle aspiration biopsy in radiofrequency ablation. Acta Cytol 46:819–22, 2002. [PubMed: 12365213]

12. vanSonnenberg E, Goodacre BW, Wittich GR, et al: Image-guided 25-gauge needle biopsy for thoracic lesions: Diagnostic feasibility and safety. Radiology 227:414–8, 2003. [PubMed: 12663819]

13. Bojarski JD, Dupuy DE, Mayo-Smith WW: CT imaging findings of pulmonary neoplasms after treatment with radiofrequency ablation: Results in 32 tumors. AJR 185:466–71, 2005. [PubMed: 16037522]

14. Daly J, VanSonnenberg E, Shankar S: The efficacy of FDG PET to assess the amount of tumor destruction after radiofrequency ablation for lung tumors. American Roentgen Ray Society Meeting, 2006. 

15. Dupuy DE, Zagoria RJ, Akerley W, et al: Percutaneous radiofrequency ablation of malignancies in the lung. AJR 174:57–9, 2000. [PubMed: 10628454]

16. Schaefer O, Lohrmann C, Langer M: CT-guided radiofrequency ablation of a bronchogenic carcinoma. Br J Radiol 76:268–70, 2003. [PubMed: 12711648]

17. Fernando HC, De Hoyos A, Landreneau RJ, et al: Radiofrequency ablation for the treatment of non-small cell lung cancer in marginal surgical candidates. J Thorac Cardiovasc Surg 129:639–44, 2005. [PubMed: 15746749]

18. Nair RT, Vansonnenberg E, Shankar S, Morrison PR, Gill RR, Tuncali K, Silverman SG. Visceral and soft-tissue tumors: radiofrequency and alcohol ablation for pain relief—initial experience. Radiol 248:1067–1076, 2008. [PubMed: 18710995]

19. Vaughn C, Mychaskiw G 2nd, Sewell P: Massive hemorrhage during radiofrequency ablation of a pulmonary neoplasm. Anesth Analg. 94:1149–51, 2002. [PubMed: 11973177]

20. Goodacre BW, Savage C, Zwischenberger JB, et al: Salinoma window technique for mediastinal lymph node biopsy. Ann Thorac Surg 74:276–7, 2002. [PubMed: 12118788]

21. Morrison PR, vanSonnenberg E, Shankar S, et al: Radiofrequency ablation of thoracic lesions: 1. Experiments in the normal porcine thorax. AJR 184:375–80, 2005. [PubMed: 15671349]

22. Shankar S, Vansonnenberg E, Silverman SG, et al: Brachial plexus injury from CT-guided RF ablation under general anesthesia. Cardiovasc Intervent Radiol 28:646–8, 2005. [PubMed: 16091989]



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