Abstract
Grade II gliomas are slowly growing primary brain tumors that affect mostly young patients. Cytotoxic therapies (radiotherapy and/or chemotherapy) are used initially only for patients having a bad prognosis. These therapies are planned following the “maximum dose in minimum time” principle, i. e. the same schedule used for high-grade brain tumors in spite of their very different behavior. These tumors transform after a variable time into high-grade gliomas, which significantly decreases the patient’s life expectancy. In this paper we study mathematical models describing the growth of grade II gliomas in response to radiotherapy. We find that protracted metronomic fractionations, i.e. therapeutical schedules enlarging the time interval between low-dose radiotherapy fractions, may lead to a better tumor control without an increase in toxicity. Other non-standard fractionations such as protracted or hypoprotracted schemes may also be beneficial. The potential survival improvement depends on the tumor’s proliferation rate and can be even of the order of years. A conservative metronomic scheme, still being a suboptimal treatment, delays the time to malignant progression by at least one year when compared to the standard scheme.
Highlights
Gliomas are the most frequent type of primary brain tumors
Other more complicated models for Low-grade gliomas (LGG) keep the same structure for the tumor cell compartment while incorporating a second compartment for a different quantity related to the radiological response, either dying cells [37, 38] or edema [40], that does not affect the response to the therapy
The time to malignant transformation depends on the fractionation scheme and tumor’s proliferation rate
Summary
Gliomas are the most frequent type of primary brain tumors. Patients diagnosed with gliomas typically die because of the complications related to the disease. No substantial progress has been made in the last decades, these types of cancer remain to be a major challenge for medicine. Low-grade gliomas (LGG) are a subgroup of gliomas (WHO grade II primary brain tumors) usually having slow growth and moderate incidence that are diagnosed mostly in young adults. The median survival time for LGG patients is about 5 years after diagnosis [1, 2].
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