Driving the tumour away

Boron neutron capture therapy, a local radiation therapy, may give cancer patients tumour-free time and relief from symptoms when other known and effective treatment methods have been exhausted.

Driving the tumour away

Some cancers are known to be highly resistant to even the best of current treatments. Malignant tumours in brain tissue often recur. There are cancers for which there is no current treatment if second line surgery does not prove effective. Also tissue can withstand only a limited amount of radiation therapy. One solution to these problems is sought in boron neutron capture therapy (BNCT), a local form of radiotherapy.

– The fascinating feature in BNCT is that the therapeutic radiation is generated when a boron nucleus, harmless in itself, captures a neutron disintegrating into high-energy lithium and alpha particles, says Leena Kankaanranta, BNCT-medical researcher from the Department of Oncology, Helsinki University Central Hospital.

Because the alpha particle and lithium are effective only within a short range, measuring a few micrometres, their effect remains within that cell in which the boron disintegrates. The boron-tagged chemical that biologically binds into tumour cells is given to the patient by intravenous route. Thus the energy from the boron and neutron reaction is targeted to the malignant tissue, while the amount of radiation normal tissues is exposed to remains at a tolerable level. Another advantage of BNCT is that effective dose of radiation may be given in one treatment session, instead of weeks-long therapy.

A special link in the chain of cancer treatments

The magnificent theory behind BNCT was discovered in the 1930s. The application of high technology and medical development in Finland in the 1990s, also in BNCT, has enabled the stages that have resulted in a safe, feasible, effective therapy for locally recurred head and neck cancer patients.

The objective of the BNCT research carried out in HUCH is to develop a current radiation therapy method for cancer that covers the entire spectrum from the first line therapies to therapies that alleviate symptoms. The first patients received the therapy in 1999 and so far approximately 250 therapies have been administered. Kankaanranta points out, however, that BNCT forms one link in the chain of various cancer treatments.

– We have treated patients for whom there was no cure to be found among current care options, including those with recurrent malignant brain tumours and those whose head and neck cancer had recurred in a previously treated area, Kankaanranta says. In the latter group, BNCT may open up a window to a tumour-free period and, in some cases, even to the possibility of cure.

Today the efficacy, safety and tolerability of BNCT has been shown in the treatment of locally recurrent head and neck cancer. Scientists are currently following up on patients whose cancer has not progressed for more than five years in the area where BNCT has been administered. The research is ongoing to achieve the set objectives, headed by Professor Heikki Joensuu.

Text: Milla Karvonen
Photo: Boneca Oy
2.12.2010
Translation: AAC Global
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