A cancer therapy which injects tiny radioactive beads into tumours could offer hope for hundreds of colorectal cancer patients whose cancer has spread to the liver.
A study released in June showed that those given the targeted radiotherapy, together with first-line chemotherapy, had their liver tumours arrested for 20.5 months, while chemotherapy alone did so for just 12.6 months.
This translates to a 31 per cent reduction in the risk of tumour progression in the liver for such patients, said Dr Iain Tan, a consultant medical oncologist leading the colorectal cancer service at the National Cancer Centre, Singapore (NCCS).
In these cases, the liver tumour cannot be surgically removed, for example, because it is too widespread.
These results are from the world's largest interventional radiology cancer trial which tracked 530 colorectal cancer patients over a six-year period.
These patients' disease had spread only to their livers.
Targeted radiotherapy, also known as selective internal radiation therapy (Sirt), uses tiny beads which carry radioactive material. These are injected into an artery to take them to the tumour site.
The beads get lodged in the capillaries around the liver tumours, where they deliver a high dose of short-range radiation to the tumours, while sparing healthy tissue.
Sirt has been used on selected patients at NCCS for the past decade as a second-line or third-line therapy, when other treatments have failed.
This is the first time a study has shown that it is beneficial as a first-line therapy, together with chemotherapy.
The finding is important as the liver is very often - 70 per cent of the time - the organ to which colorectal cancer spreads first, said Dr Tan.
Part of the reason is that vessels from the colon and rectum take blood to the liver before it goes to other organs. Many patients with colorectal cancer survive as the primary tumour is surgically removed before the cancer can spread.
However, nearly half of patients' cancer would have spread to other sites either at the time of diagnosis, or within three years of being diagnosed, said Dr Tan.
The spread of cancer to the liver is the main cause of death in colorectal cancer patients, he said.
The Singapore Cancer Registry 2009-2013 showed that colorectal or bowel cancer is ranked the top cancer among men (17 per cent), and second among women (13 per cent). There are 2,000 new colorectal cancer cases a year.
Besides NCCS, the National University Cancer Institute, Singapore (NCIS) has such radiation beads available.
In fact, it has two types - the ones used at NCCS, which are resin-coated beads; and glass beads called TheraSphere. Both types of beads contain radioactive material and emit radiation.
Recently, NCIS joined an international trial that combines chemotherapy and TheraSphere for colorectal cancer patients.
It involves patients whose cancer has spread mainly to the liver and who do not, or no longer, respond to conventional first-line treatment, said Dr Thomas Soh, a consultant at the department of haematology-oncology at NCIS.
But NCIS has mainly been using resin-coated beads to treat liver tumours that stem from colorectal cancer.
It is an option to provide control of cancer in the liver, but is not a substitute for surgery, said Dr Soh.
This therapy is also available in the private sector.
Raffles Hospital started using it in 2012 to treat selected patients whose colorectal cancer had spread to the liver, said Dr Donald Poon, a consultant medical oncologist at the Raffles Cancer Centre.
Sirt has been performed in Mt Elizabeth Hospital for some 10 years and in Mt Elizabeth Novena Hospital since it opened in 2012.
About 80 per cent of its cases are primary liver cancer.
The remaining are cancers from other parts of the body, mainly colorectal in origin, which have spread to the liver, said Dr Peter Goh, a senior consultant vascular and interventional radiologist and clinical director at the department of radiology at the hospital.
Dr Soh expects the use of radiation beads to increase. This is due to the recently published data.
But Dr Tan said it is important to ensure that this treatment can also extend patients' survival, beyond just delaying the tumour growth in the liver.
There is a need to wait a few years for all the data from this and two similar studies to be out, before this treatment can be routinely recommended, he added.
If all the studies' results are positive, the combination of targeted radiotherapy and chemotherapy can potentially help about 200 patients a year.
Nevertheless, the results gathered so far suggest that some patients may now benefit from this treatment, as a first-line option. This is best discussed on a case-by-case basis with each patient's oncologist, said Dr Tan.