Colour coding helps surgeons target cancers

PUBLISHED : Monday, 10 May, 2010, 12:00am
UPDATED : Monday, 10 May, 2010, 12:00am

A technique that highlights malignant cells through the use of a fluorescent material is enabling doctors to remove brain tumours more thoroughly than before.

The technique, first used in Germany about four years ago, has been brought to the city by a group of neurosurgeons at Queen Mary Hospital.

Although doctors say it can be applied to many forms of cancer, the technique is now only used on a severe type of brain cancer called glioblastoma multiforme.

Before surgery to remove a brain tumour, the patient drinks a liquid called 5-aminolevulinic acid, or 5-ALA. The acid is only absorbed by malignant cells, which then appear pink under blue light while healthy cells remain blue.

University of Hong Kong clinical assistant professor Gilberto Leung Ka-kit, who brought the technique to Hong Kong, said it was especially useful in brain surgery. 'For other cancers, we normally remove the tumour as well as the healthy cells surrounding it, just to make sure everything is cleared. But we cannot do the same in the brain. Each cell is important in brain function,' he said.

With this technique, doctors were able to remove the last 1 to 2 per cent of a tumour, thus reducing the chance of a relapse, he said.

According to studies, 41 per cent of patients who receive 5-ALA surgery survive after six months without any deterioration in their condition, compared to 21 per cent of those who have conventional surgery.

Leung said the technique was especially useful on patients with glioblastoma multiforme, the most aggressive form of brain cancer, because the acid acted better on more poisonous cells.

The world's annual incidence rate of glioblastoma multiforme is three to five cases per 100,000 population. In Hong Kong, only 52 new cases were recorded between July 2008 and June last year.

Leung said Queen Mary Hospital was not the only local hospital capable of doing 5-ALA surgery, and he hoped other hospitals would adopt the technique.

The surgery costs HK$30,000 to HK$40,000 in public hospitals, depending on the patient's weight.

A 52-year-old expatriate patient is so far the only person to have undergone this type of surgery in Hong Kong.

The first sign of a problem for the patient was the sudden development of a severe headache one morning in March.

He immediately went to see a doctor because the headache was so strong that he could not even read or write. He was admitted to Queen Mary two days later.

'It was quite a shock and quite devastating. One day you have a headache and then you are confirmed with a brain tumour,' he said.

He underwent the 5-ALA surgery in late March and was recovering slowly. 'My physical strength is good and I will start my chemotherapy sessions in the next few weeks,' he said.

The university, meanwhile, is participating in two international studies on new chemotherapy treatments and is now recruiting patients.

Patients who are newly diagnosed with glioblastoma multiforme can enrol in one of the two studies, which are to test two targeted therapy drugs called bevacizumab and cilengitide.

Department of clinical oncology assistant professor Janice Tsang Wing-hang said targeted therapy was very expensive and these studies provided patients with a chance to receive the latest treatment for free.

There was not yet a quota on the number of participants, she said.

Patients interested in the trials should call Ms Lai of Queen Mary Hospital on 2255 4216.

Brain drain

Glioblastoma multiforme is a particularly virulent form of brain cancer

The number of new cases of the cancer detected in Hong Kong between July 2008 and June last year: 52