How Does Interventional Radiology Help in Cancer Treatment?

Cancer treatment has traditionally been understood in terms of three disciplines: surgery removes the tumour, chemotherapy attacks cancer cells systemically, and radiation damages cancer cell DNA to prevent replication. 

Interventional radiology has slowly established itself as a fourth arm of cancer care, one that can treat tumours directly, manage the complications of cancer and its treatment, and in some cases provide options for patients who have exhausted the others. Its contributions to oncology are significant and continue to grow as the technology and techniques evolve.

Treating Tumours Directly

The most direct contribution of interventional radiology to cancer care is tumour ablation, the destruction of cancer cells using energy delivered through a needle placed under imaging guidance, without removing any tissue and without open surgery.

• Radiofrequency ablation and microwave ablation use heat to destroy tumour cells. A needle electrode is advanced into the tumour under CT or ultrasound guidance, and thermal energy is delivered until the tumour and a surrounding margin of healthy tissue have been destroyed. The procedure typically takes between thirty and ninety minutes, requires no surgical incision, and most patients go home the next day.
• Cryoablation uses extreme cold rather than heat, freezing the tumour through a probe placed under imaging guidance, then thawing it, then refreezing in a cycle that destroys the cancer cells. It is used for kidney tumours, bone metastases causing pain, and selected liver tumours, among other sites.

These techniques are most effective for tumours that are small and few in number. For liver tumours, kidney tumours, and lung tumours meeting specific size criteria, ablation produces survival outcomes comparable to surgical resection in appropriately selected patients, with significantly less disruption to the patient's recovery and quality of life.

Delivering Treatment Directly to the Tumour

Transarterial chemoembolisation, known as TACE, is used primarily for liver cancers. A catheter is advanced through the femoral artery in the groin and guided under X-ray imaging into the artery supplying the tumour. 

Chemotherapy is delivered directly into the tumour's blood supply at concentrations far higher than systemic chemotherapy could achieve, combined with embolic material that blocks the artery and deprives the tumour of blood flow. The tumour receives a concentrated local hit of chemotherapy while the rest of the body is largely spared the systemic effects.

Selective internal radiation therapy, or SIRT, uses a similar arterial approach to deliver millions of microspheres loaded with a radioactive element directly into the blood vessels feeding the liver tumour. The microspheres lodge in the tumour's small vessels, delivering localised radiation over a period of weeks from within the tumour itself.

Managing the Complications of Cancer

Beyond treating the tumour directly, interventional radiology manages many of the complications that cancer and cancer treatment produce.

• Bile duct obstruction caused by tumours compressing or invading the biliary system causes jaundice, infection, and prevents chemotherapy from proceeding. A stent placed through the skin under imaging guidance restores bile flow without open surgery, often within hours of the procedure.
• Pleural and ascitic fluid collections caused by cancer are drained through catheters placed under ultrasound guidance, relieving breathlessness and abdominal discomfort that significantly impair quality of life.
• Venous access for long-term chemotherapy is provided through implantable ports placed under imaging guidance in a brief outpatient procedure, avoiding the complications of repeated peripheral venepuncture.
• Bone metastases causing pain and instability are stabilised with cement injected under imaging guidance, providing immediate pain relief and structural support.

Conclusion

Interventional oncology is most effective when it is integrated into a multidisciplinary cancer programme where surgical oncologists, medical oncologists, radiation oncologists, and interventional radiologists review cases together. The question of whether to ablate, embolise, or resect a tumour is not one that any single speciality should answer alone.