Combining two separate observations of cells in brain tumours could
enable doctors to improve the success rate of radiotherapy. Speaking
today (23 January) at the Institute of Physics Simulation and Modelling
Applied to Medicine conference in London, chemical engineer Dr Norman
Kirkby from the University of Surrey will explain how using the correct
time intervals between a sequence of low dose radiotherapy sessions
could increase the chance of curing brain cancers that tend to resist
The work started with the discovery that there is a class
of brain cancers (gliomas) that are susceptible to low doses of
radiation, but can resist high doses. These cancers can occur in
children as well as adults. They are difficult to treat because they do
not form solid lumps that can be removed by surgery. Instead they
spread in a diffuse manner through the brain.
The question was,
would it be possible to find a way of getting the most benefit from
giving multiple sessions of low-dose therapy? A team of chemical
engineers, cell biologists and clinicians, drawn from the University of
Surrey, Addenbrooke’s Hospital in Cambridge and The Gray Cancer
Institute at Mount Vernon Hospital in Middlesex, came together to see
if they could make some accurate predictions.
colleagues built a mathematical model that described the biology of
cancer, and the effect that radiation has on it. Tumours grow when a
number of cells multiply. For this to occur, cells take part in a cycle
of activity, in which they first produce new copies of the genetic
information, then check that the copies have no errors, before finally
splitting the cell into two. During the checking phase of the cell
cycle they also repair any errors in the genetic code.
works by damaging each cell’s DNA. But if the therapy is given when
cells are in the repair phase of their cycle, they will simply sort out
the damage and carry on growing.
The new mathematical model is
enabling the team to calculate the best time intervals to leave between
doses of radiation, so that the maximum number of cells are caught at a
time when they can’t repair the damage. It suggests that a patient
should receive small doses at fairly precise times, several times a
day. This is new. Standard systems of treatment give larger doses with
intervals of a few days.
"The model is convincing, but the
challenge will be to find ways of fitting this treatment schedule into
the diaries of a working radiotherapy department," says cancer expert
Dr Neil Burnet.
Team member Dr Susan Short hopes that giving low
doses of treatment at optimum time intervals will mean that they can
destroy the cancer cells in people’s brains without causing excessive
damage to the normal brain tissue.
Source: University of Surrey. January 2002.