Tumor Ablation: RFA, Microwave, and Cryoablation Explained

Ablation kills a tumor where it sits. No specimen is taken out. A doctor threads a needle-sized probe to the tumor and delivers energy that destroys the cells.

RadiologyInfo.org describes the guidance step. Ultrasound, CT, or MRI steers the probe. An interventional radiologist usually does the work. The setting is a radiology suite, or sometimes an operating room.

NCI's PDQ summary on primary liver cancer sorts ablation by what kills the cells. One route is a change in temperature. That covers RFA, or radiofrequency ablation, plus microwave and cryoablation. A second route is a chemical. That is PEI, or percutaneous ethanol injection, which is an alcohol shot into the tumor. A third route damages the cell membrane directly, by electroporation.

RFA passes a current through tissue to heat it until cells die. NCI's liver summary calls RFA a well-established technique for liver cancer.

Microwave ablation (MWA) heats tissue with microwave energy. PDQ lists it beside RFA as a temperature-based method.

Cryoablation freezes instead. NCI's cryosurgery fact sheet says the cold comes from liquid nitrogen or argon gas flowing through a cryoprobe. More than one probe may be used to freeze different parts of a tumor. When frozen tissue thaws, the cells die. Inside the body, that dead tissue is absorbed. On the skin, it forms a scab that falls off.

RadiologyInfo states plainly that for many tumor types there are no known differences between heat-based and cold-based treatment. Claims that one is gentler are not supported there.

The size limit people hear about is not a rule of thumb. It comes from outcome data.

NCI's liver PDQ reports that RFA does best in tumors under 3 cm. In that group, 5-year overall survival may reach 59%. Recurrence-free survival may not differ much from surgery. Above 3 cm, PDQ says local control drops off steadily.

PEI has its own bracket. It applies to a single tumor under 3 cm in Child-Pugh class A cirrhosis, the mildest grade of liver damage. There, PDQ puts 5-year overall survival at 40% to 59%.

Head to head, PDQ says randomized trials in Child-Pugh class A cirrhosis favored RFA. RFA beat PEI on complete response and on local return. Some trials also showed better survival. RFA needs fewer sessions too. PDQ notes RFA may carry more complications than PEI. But it says both have fewer complications than cutting the tumor out.

PDQ names anatomic limits that decide the answer more than size does.

PDQ calls ablation relatively contraindicated near bile ducts. The same goes for the diaphragm. It also goes for other belly organs the probe could injure.

Then there is the heat-sink effect. When a tumor sits beside a major blood vessel, flowing blood carries heat away. PDQ says thermal methods such as RFA may never reach the temperature needed, which can prevent complete tumor destruction.

RadiologyInfo adds a third limit. Tumors under 2 to 3 mm often cannot be seen on scans. What cannot be seen cannot be targeted. Ablation is also local. It treats one site.

For liver cancer, PDQ positions ablation for when removal by transplant or resection is not feasible or advisable. It calls ablation useful for early hepatocellular carcinoma sitting deep in the liver. Cutting there would cost too much working liver tissue.

NCI's renal cell PDQ lists ablation for stage I kidney cancer. Its option list runs: partial nephrectomy, radical nephrectomy, simple nephrectomy, cryotherapy, thermal ablation, stereotactic radiation, and trials. PDQ calls cryoablation, thermal ablation, and stereotactic radiation curative choices. They are for people who cannot have the tumor cut out.

NCI's cryosurgery fact sheet reaches further. Its list runs long. Retinoblastoma, an eye cancer of childhood. Basal cell and squamous cell skin cancers. Skin lesions from AIDS-related Kaposi sarcoma. Early-stage prostate cancer. Liver cancer that has stayed in the liver. Bone cancer, mostly chondrosarcoma. And non-small cell lung cancer.

RadiologyInfo gives concrete timings. Each ablation takes about 10 to 30 minutes. The whole visit usually runs one to three hours, longer when a large tumor needs the probe repositioned or several probes placed.

Monitors track heart rate, blood pressure, oxygen, and pulse. An IV line delivers a sedative. The skin over the target is cleaned, draped, and numbed. Some cases add deeper sedation or general anesthesia. That choice is made at the first visit.

At the end the probe comes out, pressure stops any bleeding, and a dressing goes on. No stitches are needed. Most ablation is outpatient, though an overnight stay for observation is sometimes needed.

RadiologyInfo puts return to usual activities at one to seven days, with no heavy lifting for at least 72 hours. About 10% of patients still have pain a week later.

Fever is common enough to expect rather than fear. About one-third develop fever and flu-like symptoms within days, which RadiologyInfo says often clears within 10 days. It also describes post-ablation syndrome in roughly 1 in 4 patients. Flu-like symptoms start 3 to 5 days out. They usually last about 5 days. Now and then they run two to three weeks. RadiologyInfo names acetaminophen or ibuprofen for managing them.

Infection serious enough to need antibiotics appears to run under 1 in 1,000, per RadiologyInfo. Bleeding and injury to nearby structures are also listed.

Neither RadiologyInfo nor NCI's cryosurgery page publishes a temperature cutoff for calling the team after ablation. That number has to come from the discharge sheet for the exact procedure. It is worth asking for before leaving.

RadiologyInfo says the interventional radiologist sends a signed report to the referring doctor. Follow-up may include a physical check, imaging, and blood tests. Imaging matters here. An untreated rim at the tumor edge can require a second session.

Ablation sits alongside other local options. The specialty behind it is described in interventional radiology in cancer care. Trade-offs against an operation are covered in surgery for cancer. The radiation choice NCI lists for stage I kidney tumors is weighed in SBRT vs. surgery.

Your own temperature cutoff has to come from the discharge sheet for the exact procedure, since neither source above publishes one. Ask for it before you leave.

• Call 911 or go to an emergency department if severe belly, chest or shoulder pain comes on suddenly, or you feel faint, or you cough up or pass blood. Bleeding and injury to nearby structures are listed complications.
• Call your care team the same day if fever or chills arrive alongside pain that is worsening rather than easing, or the puncture site turns red, hot, or starts oozing. Infection needing antibiotics is rare, under 1 in 1,000, and is treated quickly.
• Call your care team within a day or two if flu-like symptoms are still going beyond about 10 days, or pain is unchanged a week on, or a fever keeps returning after the first few days.

• NCI PDQ: liver cancer, HP version
• NCI PDQ: renal cell cancer, HP version
• NCI: cryosurgery
• RadiologyInfo: thermal ablation