Glioblastomas, the most common form of brain cancer, are very aggressive and have a standard three-stage treatment. The first stage is the surgical removal of the tumor. This is followed by radiotherapy and chemotherapy (CRT) with Temozolomide (TMZ). TMZ would then be used for a second time following the CRT. This treatment can extend the overall survival (OS) of patients by four-fold. This therapy was first put forward in 2005 and has remained the standard to this day.
A group from the Rambam Medical Center out of Israel has used this method to treat glioblastomas for years but were curious about the timing of the CRT post-operation. Their patients’ circumstances often delayed the CRT by more than six weeks post-operation, beyond the recommended timeframe. They wanted to investigate if this changed the OS of their patients, so they examined patient data from 2005-2014 in a retrospective study to find out.
They used the data from two hundred and four patients with high-grade gliomas. Of these patients, forty-seven underwent CRT within four weeks of operation. Seventy-two were treated between four to six weeks post-operation. Finally, eighty-four underwent CRT after the recommended six weeks. All underwent the standard treatment.
Analyzing the data, they found that postponing the CRT to beyond six weeks after tumor removal seemed to correlate with better OS rates. This data was particularly strong in patients over the age of sixty but weaker with the rest of the patients. They did note that patients tended to have more CRT interruptions if they waited till beyond six weeks for treatment.
This result seems to go against the standardized procedure for glioma therapy. However, a growing number of investigations seem to agree. Many papers from other studies point to radiotherapy being the main culprit behind the poor prognosis of those undergoing CRT within four weeks of tumor removal. The team also points out that patients with a poor prognosis often receive treatment faster than those with a better prognosis. They also mention the subtle differences in radiotherapy treatment that may introduce bias.
The group concludes, “Our current approach is to initiate CRT within six weeks after surgery, similar to what is recommended in the literature, but the data from this study provide us with information that no major harms was done in patients who were somewhat delayed.” The data points to radiotherapy as the critical factor in the poorer prognosis of those patients treated within four weeks of surgery. With plenty of conflicting research on this topic, a thorough investigation is needed before changing the standard of glioma treatment with this new observation.