20 April 2012
Researchers have found evidence that high dose vitamin C could make brain tumours more susceptible to radiation therapy.
Glioblastoma multiforme (GBM) is a highly aggressive brain tumour that is ultimately fatal, because it is very resistant to treatments such as radiation therapy.
In radiation therapy a lethal dose of radiation is delivered to a tumour whilst sparing the surrounding healthy tissues as much as possible. Radiation kills both normal and cancerous cells by generating free radicals that destroy their DNA, however healthy cells have repair mechanisms that enable them to recover from the treatment more quickly.
High dose vitamin C also generates free radicals in the acidic, metal-rich environment of a tumour, but not in normal tissues. Dr Patries Herst, a senior lecturer in Radiation Therapy at the University of Otago, Wellington, therefore hypothesised that high dose vitamin C may work synergistically with radiation treatment to increase free radical damage to GBM tumours.
In collaboration with Dr Melanie McConnell, Dr Herst investigated the effect of combining high dose vitamin C with radiation on the survival of cancer cells isolated from GBM tumours. She found that pre-treating GBM cells with vitamin C did indeed make it easier to kill them with radiation.
The use of high dose vitamin C as an anti-cancer treatment is very controversial. Early studies using oral and intravenous vitamin C showed a survival benefit for terminally ill patients but later studies using only oral vitamin C did not. Recent research has shown that vitamin C accumulates in the blood at concentrations high enough to kill cancer cells only when given intravenously.
If carefully designed clinical trials support Dr Hersts basic research findings that combining high dose vitamin C with radiation therapy improves patient survival, there may be merit in combining both treatments for radiation-resistant cancers such as GBM.
Pictured above: Dr Patries Herst (sitting) and Dr Melanie McConnell