Millions of radioactive micro-spheres travel through blood vessels to the liver and deliver their payload at the site of the tumour.
“Cure” is a big word in cancer medicine and oncologists use it with considerable caution. If they can find a way of curing even a tiny percentage of people considered incurable, it is regarded as a huge advance.
Scientists on the cusp of a cure have to resist the temptation of overstating their position.
Although Australian oncologists have cured a small number of patients with liver cancer, they shrink back from calling their treatment curative.
They use an innovative Australian therapy which involves placing tiny radioactive spheres in the liver. These spheres deliver high doses of radiation to the cancerous tumours.
“The conservative point of view at this stage is that we are not sure it is curative for a small number of patients,” says Peter Gibbs, an oncologist at the Royal Melbourne Hospital and an associate professor at the Walter and Eliza Hall Institute of Medical Research.
“We certainly do have patients where this treatment has shrunk the liver tumours to the point where they could be surgically removed and some of these people have gone on to survive long-term. In a small percentage of patients it does appear to be curative.”
Gibbs says the “poster girl” for this therapy is a woman who was first treated in 2002 at the Royal Melbourne Hospital.
She had five liver tumours which disappeared after therapy and have still not come back.
These tumours were secondaries from her colorectal cancer.
After the primary cancer in her colon was surgically removed, she was referred to Gibbs to have the liver secondaries treated.
“I am very confident that she is cured,“ he says.
“It’s a guess but probably in 3, 4 or 5 per cent of patients, this treatment may control and cure the cancer. We just don’t know.”
Selective internal radiation therapy
This therapy, known as selective internal radiation therapy, or SIRT, confines the radiation to the liver so adjoining tissues are not damaged.
The spheres are introduced through the groin and sent into the liver via the circulatory system.
Each one is one-third the diameter of a strand of hair and remains active for three days.
SIRT is at present used in about 300 patients a year in Australia. In addition to liver secondaries from colorectal cancer, it is also used on primary liver cancer that can develop in people with hepatitis or cirrhosis.
It is now a last line of treatment, proven to be moderately effective at controlling cancers when all else has failed.
But work is under way to see if it will have a bigger impact if it is given early in the treatment cycle.
Last year the American Journal of Clinical Oncology published results of a small pilot study, using SIRT in combination with chemotherapy as a first line of treatment.
The study involved 20 patients.
Six to eight months later, the tumours that received the combination therapy were 60 per cent smaller compared with the tumours which received only the chemotherapy.
Now a study involving 500 patients with inoperable liver metastases from a primary colorectal cancer is being conducted in 100 leading hospitals across the world.
The study aims to test if this first line combination of SIRT and chemotherapy is more effective than chemotherapy alone.
Recruitment is complete and first results should become public in 2015.
Liver cancer is more common in men than women and the incidence rises with age.
In Australia, the average age of diagnosis is 66.
SIRT is expensive, with treatment costing around $14000. Health insurers provide cover only when it is used to treat liver secondaries from colorectal cancer.
Gibbs says there definitely is a group of patients in whom the combination treatment shrinks their tumours to point where they can be surgically removed.
In some this may be life-extending, in some it may lead to a cure.
Gibbs points out, however, that the primary focus of the new global study is on patients living longer with acceptable side effects.
The hope is that a small percentage will be cured.
Rather than making a small difference in a big number of people, which is typical of most new cancer therapies, Gibbs says this is likely to make a big difference in a small number of people.
When an inaudible time bomb finally goes off
For 40 years, Bozidar Drulovic has lived with a time bomb.
As a doctor, he made a conscious decision not to let it rule his life, but now he concedes he could have paid more attention to it.
As an intern in Belgrade in the 1970s, he was operating on an abscess in a patient known to have Hepatitis B. Something happened, perhaps a needle-stick injury, and he was infected.
“A short while later, I knew I had a 90 per cent chance of developing cancer during my life,” he says.
Drulovic, now 64 and a general practitioner in Melbourne, lives a full and rich life with his wife, two children and grandchildren.
He has always played sport and does not drink or smoke.
Fortunately, his hepatitis was indolent and apart from blood tests to check liver function, very occasionally he would have a scan too.
About three years ago a scan turned up a 3.5 centimetre lesion, which the report said was probably a haemangioma, a non-cancerous dense collection of dilated blood vessels.
The diagnosis was so appealing that against his better judgement, Drulovic accepted it.
He put it to the back of his mind and last year, in a bid to improve his fitness, he put himself on diet and successfully shed 14 kilograms.
Drulovic acknowledges that had he not been a doctor, he probably would have sought specialist opinions earlier.
As he was still working ten hours a day, he was not that surprised that his energy levels were not as high as he would have liked.
Then, in February this year, there was a sudden pain in his liver. It subsided after half an hour but was enough for him to ask a work colleague to do an ultrasound on him the next day.
The result didn’t look good. There was a 10-centimetre tumour which was bleeding and looked like a cancer. If it was, its size and position would make it inoperable.
A biopsy returned dead tissue but malignant cells were found, meaning cancer was present in his liver.
“But I was mentally OK because, after so many years of waiting, I was ready for it,“ says Drulovic.
He now sought expert opinion and found there were only two options: chemotherapy or selective internal radiation therapy, SIRT. As chemotherapy was minimally effective and highly toxic, he opted for SIRT.
First he underwent a trial with a test dose to check there was no leakage of radiation to his lungs, stomach or other structures.
This was essential as the dose is 30 times higher than that used in external radiation.
In mid-April Drulovic had the full treatment. “It was ok. Afterwards I had no pain, no temperature, no vomiting and no side effects. But the first week was rough.
“I was asleep for two hours and awake for two hours, night and day.”
By late May he was back at work and says the only after-effect is having less energy than he would expect.
The tumour takes between two to six months to shrink and although he has no shrinkage yet, his liver function tests give good reason for hope.
“If a tumour is inoperable, SIRT is an excellent alternative. It was the only option for me and I didn’t hesitate for a second.”
Drulovic is gaining weight, is pain-free and describes himself as realistic rather than optimistic.