Interventional Radiology in lung cancer: from diagnosis to treatment

Ioannis Dedes, Danai Chourmouzi

Procedures performed by an interventional radiology department are becoming increasingly important in the management of patients with lung cancer. Interventional radiology procedures include imaging-guided biopsies to obtain samples for cytologic or pathologic testing without affecting adjacent structures. Fluid collections can also be sampled or drained using interventional radiology techniques.

Transcatheter chemoembolization is a procedure that delivers a chemotherapeutic agent to a tumor along with embolization particles that have an ischemic effect on the mass. Tumor ablation for treatment are performed effectively under CT guidance. Cancer complications can also be treated with interventional radiology techniques. Examples include pain control procedures such as vertebroplasty. Interventional radiology techniques typically represent the least invasive definitive diagnostic or therapeutic options available for patients with lung cancer.

A.Diagnosis

A.1.Computed tomography guided transthoracic needle biopsy

During the past 30 years, numerous studies have proved the accuracy and safety of radiographically guided transthoracic lung biopsy procedures.

Actually Computed tomography (CT) guided transthoracic needle biopsy (TNB) of lung lesion is now an established and safe technique for the diagnosis of malignant neoplasms. Fine needle aspiration (FNA) provide high-quality material for the microscopic diagnosis of malignancy.
A sensitivity for the diagnosis of malignancy has been reported to 90–97%.

Automated cutting biopsy devices are also currently used as well. A core biopsy specimen obtained in addition to fine needle aspiration biopsy increases the diagnostic accuracy for non-malignant lesions and characterization of cell types in patients with carcinoma. Recent studies have reported a high specific diagnosis rate for both benign and malignant lesions following biopsy using automated biopsy devices which permit the combined evaluation of cytology and histology and thereby improved the overall accuracy.

CT-guided TNB is generally regarded as a safe procedure with limited morbidity and extremely rare mortality. Factors which may influence the accuracy and complication rate of CT-guided lung biopsy include the number of needle passes and the lengththrow of the needle. Pneumothorax remains the most frequent complication, and a tube thoracostomy is occasionally required for treatment . The reported frequency of pneumothorax for CT-guided procedures varies from 8% to 64%. Fatal complications due to systemic air embolism, hemorrhage, or pericardial tamponade have been reported, but these are rare. Coaxial biopsy systems diminish the number of passes through the visceral pleura and theoretically reduce the likelihood of pneumothorax.

CT-guided transthoracic needle aspiration biopsy is useful as a diagnostic tool even for small solitary pulmonary nodules with diameters of less than 20 mm. However the diagnostic accuracy is significantly improved for lesion with size larger than >10 mm).

A.2.Imaging-Guided Fluid Aspiration

Imaging-guided aspiration of fluid collections is another diagnostic aid. CT can be used to place a small (18- to 22-gauge) needle into a fluid collection to determine whether the collection is benign or malignant.

If indicated, a drainage catheter may be placed at the same time as the needle aspiration. Catheter drainage may be especially helpful in patients with fluid collections that otherwise might require surgical drainage (e.g., pericardial effusions in pericardial tamponade or loculated fluid collections). Sclerosing agents may also be injected into the indwelling catheter. This measure can decrease the likelihood of fluid reaccumulation in patients with conditions such as recurrent malignant pleural effusions.

B.Treatment

B.1.Percutaneous radiofrequency ablation of lung tumours

Surgical resection still represents the mainstay of treatment, which achieves the major potentiality of cure in the case of localised lung cancer. Nevertheless, surgical treatment is not always feasible because of coexistent chronic obstructive broncho-pneumopathy or other associated diseases. Higher-stage inoperable lung tumors respond poorly to chemotherapy and radiotherapy regemnets, and therefore, alternative treatment is desirable.

Moreover in patients with pulmonary metastasis, the number and location of the lesions could require a sacrifice of pulmonary parenchyma, which is out of proportion with the aim of this therapeutic option, often palliative.

In all above scenarios minimally invasive treatments often receive great interest, as is happening for radiofrequency ablation (RFA). This method has been successfully used for the treatment of hepatocellular carcinoma , hepatic metastases , osteoid osteoma and other solid tumours . Thin metallic probes, similar to aspiration biopsy needles, are percutaneously inserted into the lesion using computed tomography (CT) scanning. Radiofrequency energy is then applied in order to achieve a temperature greater than 60 °C (in most cases 90 °C). Thus, coagulative necrosis of the tumour is induced in a controlled manner.

All recent clinical trials reported, in fact, a good local response, with an elevated tolerability and a very low rate of complications. However the value of RFA in lung tumors has not yet been established.
It is necessary to underline the purpose of RFA, which regards only the local treatment of the tumour, with all its limits.

B.3.Regional chemotherapy for carcinoma of the lung

The potential benefit of regional chemotherapy is to reach high local drug concentrations in the treated area by reducing systemic side effects. Today, different application forms are available, such as intra-arterial infusion, sometimes in form of chemoembolization. For transcatheter chemoembolization, a chemotherapeutic agent is mixed with lipiodol and small embolization particles (sponge or microspheres) and injected into an artery that supplies a tumor. With this direct delivery technique, far lower dosages of the chemotherapeutic agent are needed than when the agent is delivered systemically. Concurrent injection of embolization particles causes vascular stasis and has an ischemic effect on the tumor itself.

The embolization particles also decrease blood flow through the tumor and prolong the time that the chemotherapy agent is in contact with tumor cells. Up to now, only a few of these techniques have reached a level of standardization combined with an efficacy superior to conventional systemic chemotherapy to be accepted as a standard treatment by the oncologic community.

The treatment of lung metastases of solid tumors is still a major problem, as many patients manifest extensive unresectable disease or pulmonary recurrence in the resected or contralateral side after complete resection.

The use of intravenous chemotherapy is primarily limited because of systemic toxicity and so far has not achieved a curative effect in patients with unresectable pulmonary metastases . As with neoadjuvant or palliative treatment of liver metastases, the regional application of cytotoxic agents might also be a method for improving the therapy of unresectable lung metastases.

C.Treatment of Cancer-Related Complications

Transcatheter embolization is the method of choice in the management of pulmonary hemorrhage in cases of lung cancer. Interventional radiology can play a significant role in the management of pain with invasive procedures such as regional analgesia achieved with local anesthetics, injection of neurolytic agents, alcolization of tumor, analgesic percutaneous vertebroplasty. Interventional radiologist is part of multidisciplinary team and palys an active role in pain management, and improving quality of life, particularly in the advanced cases.

Surgery, chemotherapy and radiation therapy remain the mainstays of cancer treatment, but interventional radiology continues to grow in importance as an alternative mode of therapy or an altogether new form of treatment for patients with lung cancer. Many interventional radiology procedures can be performed on an outpatient basis or during a short hospital stay. Consequently, these procedures tend to be less expensive than other forms of therapy and frequently are associated with less morbidity