Management

Role of Interventional Radiology in Cancer Care

It is often possible to place a stent in an obstructed organ to bypass the obstruction and facilitate internal drainage

"Many interventional radiology procedures can be performed on an outpatient basis or during a short hospital stay" - Dr Vivek Saxena Consultant Interventional Radiology Max Super-speciality Hospital New Delhi

Based on the latest cancer registry data it is estimated that there will be 8, 00,000 new cancer cases in India every year. While most cancer patients will be treated with some combination of conventional surgery, chemotherapy and radiation therapy many others will benefit from the new technologies and techniques that are building interventional radiology into a major force in cancer treatment.

Interventional radiology is a superspeciality of radiology in which minimally invasive procedures are performed using image guidance by CT / ultrasound / fluoroscopy. Images are used to direct these procedures, which are usually done with needles or other tiny instruments like small tubes called catheters. The images provide road maps that are used to guide these instruments through the body to the areas of interest.

Interventional radiology techniques typically represent the least invasive definitive diagnostic or therapeutic options available for patients with 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 risk and procedure related complications. The primary goals of management of cancer include diagnosis of cancer or cancer-related diseases, the treatment of cancer and the treatment of complications arising from cancer. Interventional radiology has an increasing role to play in all aspects of management of cancer patients.

Diagnosis of Cancer or Cancer-Related Diseases

Many disease processes have a similar appearance and it can be difficult to establish whether a mass is cancerous or not on imaging alone. Before any treatment can be initiated, it is essential that a pathological diagnosis is available. With image guidance (CT or ultrasound), tissue samples can be obtained by inserting needles into the exact area of abnormality. The image guidance enables us to avoid important adjacent structures, such as blood vessels or bowel. This reduces the time required and the risk involved as compared to a surgical or open biopsy.

Transjugular liver biopsy is a specialized procedure which is done when percutaneous liver biopsy cannot be done as in patients with large abdominal fluid collections, morbid obesity, bleeding tendencies or when the liver is grossly shrunken and pressure measurements in the blood vessels of the liver are required.

Imaging-guided aspiration of fluid collections is another diagnostic aid. A drainage catheter may be placed at the same time as the needle aspiration in patients with infected fluid collections or fluid collections that would otherwise require a more extensive surgical drainage procedure.

Adhesive agents may also be injected into the indwelling catheter. This procedure can decrease the likelihood of fluid reaccumulation in patients with conditions such as recurrent cancerous fluid collections in the lung (pleurodesis).

Treatment of Cancer

Recent advances in interventional radiology have enabled the radiologist to bring about direct destruction of the tumour. For inoperable liver tumours, Radio-Frequency Ablation (RFA) offers a non-surgical, localised treatment that kills the tumour cells with heat, while sparing the adjacent healthy tissue. Thus, this treatment is much easier on the patient than routine systemic chemotherapy and most people can resume their usual activities in a few days. In this procedure, the interventional radiologist guides a small needle through the skin into the tumour. From the generator, radiofrequency energy is transmitted to the tip of the needle, where it produces heat in the tissues and destroys it. The dead tumour tissue shrinks and slowly forms a scar. Depending on the size of the tumour, RFA can shrink or kill the tumour, extending the patient's survival time and greatly improving their quality of life while living with cancer. Because it is a local treatment that does not harm healthy tissue, the treatment can be repeated as often as needed to keep patients comfortable. It is a very safe procedure, with complication rates on the order of two to three percent. By decreasing the size of a large mass, or treating new tumours in the liver as they arise, the pain and other debilitating symptoms caused by the tumours are relieved.

Other methods involve direct injection of sclerosing agents (e.g., absolute alcohol) into metastatic or primary tumours of the liver. This is mainly done in small sized tumours (less than five cm). Although alcohol ablation therapy has been a successful mode of therapy, its use has generally been confined to patients with cirrhosis whose tumours are small in size and are anatomically amenable to a per-cutaneous approach. It can be used in conjunction with other treatment modalities like RFA or chemoembolisation. Another newer modality is cryoablation, in which the probe delivers an extremely cold gas to the tumour. The 'ice ball' that is created around the needle grows in size and destroys the frozen tumour cells.

Alternatively, other techniques involve delivery of chemotherapy or radiation agents as close to the tumour as possible. These therapies have mainly been used in liver tumours in which systemic chemotherapy has not given encouraging results. In Transcatheter Chemo- Embolisation (TACE), chemotherapeutic agents are mixed with small sponge particles and injected into the artery that supplies a tumour. With this direct delivery technique, far lower dosages of the chemotherapeutic agent are needed than when the agent is delivered systemically. This almost eliminates the side effects of the chemotherapy. Concurrent injection of sponge particles cuts off the blood supply to the tumour which not only has an ischemic effect on the tumour itself, but also prolongs the time that the chemotherapeutic agent is in contact with tumour cells, thus enhancing its efficacy. Patients who undergo transcatheter chemo-embolisation typically stay in hospital for only one or two days, and the procedure may be repeated multiple times in the same patient. TACE does confer some survival advantage over systemic chemotherapy alone and also increases the quality of life of the patient. Radioembolisation is a latest technique of intra arterial radiotherapy. It is an outpatient procedure that involves delivery of Yttrium 90 labeled microspheres into the blood vessels supplying the tumour. These microspheres get embedded in small blood vessels inside the tumour and emit beta particles which treat the tumour. Since the average penetration of a beta particle is only two millimeters, the radiation therapy delivered is highly targeted and is limited to the area of interest. This reduces the sometimes debilitating side effects of radiation therapy delivered in the conventional manner and increases the efficacy of the treatment as a far larger dose of radiation can be given to the tumour. It is useful even in large or multi-focal liver tumours and in patients with substantially compromised liver function in whom other treatment modalities, even chemoembolisation are not an option.

Treatment of Cancer-Related Complications

Complications arising from cancer include pain or bleeding, obstruction of vital organs such as ureters and biliary ducts, and thrombo-embolic disease of the lower extremities. Pain control is essential in patients with cancer. Pain often arises from local spread of a tumour, such as invasion of the adjacent nerves. Ablation of the nerve plexus with a sclerosing agent such as absolute alcohol can be easily and safely performed under imaging guidance in the interventional radiology suite, and this procedure often greatly relieves the patient's pain.

If a patient's pain arises from a hyper vascular process, such as renal carcinoma that metastasizes to bone, transcatheter embolisation (injecting small sponge particles through a catheter placed into the artery supplying the tumour) may significantly ease the patient's pain and decrease the likelihood of pathologic fracture.

Vertebroplasty is a technique in which cement is injected through a needle into a collapsed or weakened vertebra to keep the vertebra from collapsing further and causing symptoms of cord compression such as pain or loss of sensation.

Percutaneous placement of drainage catheters, such as percutaneous nephrostomy tubes and biliary drainage catheters, is performed under imaging guidance to allow external drainage of obstructed urine or bile for the purpose of preventing or treating organ failure and infection.

In addition to placing external drains, it is often possible to place a stent in an obstructed organ to bypass the obstruction and facilitate internal drainage. The placement of metal and plastic stents in the interventional radiology suite is performed from an entirely percutaneous approach, precluding the need for surgery or endoscopy.

The role of interventional radiology in the care of patients with cancer continues to expand. Its greatest contribution has been the palliation of distressing symptoms produced by malignant disease. Minimal invasive treatment helps cancer patients extend and improve their quality of life.

vivek.saxena@maxhealthcare.com