01 Jul 2010
The surgical removal of a liver tumour offers the best chance of a cure. Unfortunately for many liver cancer patients, the disease is often at an advanced stage by the time they complain of symptoms. If the tumour is too large, or has invaded surrounding blood vessels or vital organs, surgery may not be an option.
Surgery is also not practical if many small tumours are found.
Such conditions are typical of most liver cancer patients referred to the Interventional Radiology Centre at Singapore General Hospital (SGH), which has treated more than 300 liver cancer patients since its launch in January 2009.
Some patients come in after suffering a recurrence of the disease, which was the case with Mr Hoe Kwong Sen, a 60-year old retired businessman.
After being diagnosed with primary liver cancer, Mr Hoe had surgery in 2007 to remove a segment of his liver. He underwent a second procedure last December when his cancer recurred. That also didn’t stop the cancer, and in March, ultrasound and MRI scans showed Mr Hoe’s cancer had returned yet again.
“My doctors felt that another surgery would be too risky for me. So they recommended that I undergo a different procedure,” said Mr Hoe.
Dr Richard Lo, Interventional Radiologist and Senior Consultant, Department of Diagnostic Radiology, SGH, said: “Since Mr Hoe’s tumour was localised, we decided on a local treatment rather than subject him to another open procedure.
Moreover, his liver functional reserve [the amount of functioning liver remaining after surgery] was reduced as a result of previous surgery.”
Cook the cancer
In April, Mr Hoe underwent radiofrequency ablation (RFA), a relatively new procedure in which a 15cm-long needle is inserted through the skin. With the help of ultrasound and CT images, the insulated needle is guided straight into the tumour.
Then, the heating component at its tip is activated to burn the tumour cells.
“By heating the needle’s tip to 60 or 70ºC, we essentially cook the tumour todeath. It is a very precise and controlled procedure because the burn margins can be accurately determined by the specific needle tip we use, which is chosen according to the size of the tumour,” said Dr Lo.
Heat is an effective means of killing human tissue as cells can only tolerate temperatures of up to 45ºC. Anything higher, and they undergo irreversible damage and begin to die.
The minimally invasive procedure requires a 1-2mm-wide needle prick, and a single procedure typically takes about 10 to 15 minutes. If there is more than one tumour to be burnt, the needle is inserted in a different place.
Mr Hoe, who spent three days in hospital, said: “There was considerably less pain compared to my previous surgeries, and the wound from the needle entry healed after a few days.” Initial scans indicate he is doing well. Should his cancer return, Mr Hoe can undergo the procedure again.
Not all liver cancer patients can be treated by radiofrequency ablation. In Mr Hoe’s case, he had a 2cm tumour. Radiofrequency ablation is considered unsuitable if a tumour is bigger than 5cm or if there are more than three to four separate tumours.
“Technically, you can target multiple tumours, but the patient may not be able to tolerate multiple burns. RFA is also difficult if the tumour is situated in a very deep or awkward location within the liver,” said Dr Lo, who has done up to three radiofrequency ablation procedures on a patient in one session.
Blood blockade
If radiofrequency ablation is not suitable for a liver cancer patient, interventional radiologists may undertake a transarterial chemoembolisation (TACE), provided the patient’s liver function and reserve are satisfactory.
This is another targeted approach that works by blocking the blood supply to a tumour and administering cancer drugs into the blood vessel feeding it. Through a small prick in the groin to access the main artery in the patient’s thigh, a tiny tube is guided via X-ray into the liver’s main artery.
Said Dr Lo: “Once the vessel supplying the tumour is identified, a cocktail of drugs is injected into it. Besides chemotherapy drugs, we use a compound to help concentrate the chemotherapy effect within the tumour and an agent to prevent blood flow through that particular vessel.”
With the tumour starved of blood supply, its growth is stunted, causing it to eventually shrink and die. Although multiple tumours are harder to treat with this method, it is still effective. The process can be repeated after two to three months if the tumour persists.
“It cannot cure bigger tumours, but it can help prolong survival. Compared to the traditional practice of administering chemotherapy into the body’s main circulation, TACE’s side effects are nowhere as bad since the drugs stay within the liver,” said Dr Lo.
Citing recent studies by the renowned Hospital Clinic of Barcelona in Spain and the University of Hong Kong, Dr Lo highlighted the reported improvement in survival rates of liver cancer patients who have undergone the procedure.
“Interventional radiology has definitely brought about important developments in the control of liver cancer, and patients have been shown to tolerate it better than open surgery. With new technology and improved imaging techniques, we hope to eventually achieve our ultimate goal – to offer a cure, not just to prolong life.”
New advances
A new treatment for liver cancer is undergoing advanced trials at SGH. Known as selective internal radiation therapy (SIRT), it is similar to transarterial chemoembolisation in its delivery except for the substance injected into the blood vessel – a radioactive material called Yttrium-90.
Said Dr Lo: “We are already seeing signs that SIRT is more effective than chemotherapy drugs in some patients. This is because radioactive particles remain trapped within the tumour, and their
short half-life [lifespan] causes fewer toxic side effects.
“We hope to be able to offer SIRT as another treatment option soon, as patients tend to tolerate it even better than TACE.”
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