Glioma
The chances of contracting glioma - a brain or spine tumor that is the fastest-growing cancer known to oncologists - is about 4 in 100,000, making it a relatively rare form of cancer. Glioma is found mostly among men, often those in their 70s and 80s, though it has, in recent years, begun appearing much more frequently in 50-year-olds and even in those much younger. About 30,000 people are diagnosed with glioma annually in the U.S.
Gliomas are ranked by cell types and in stages from 1 to 4, with stage 1, on a scale published by the World Health Organization, being the most benign, and stage 4 the most aggressive. Stage 1 and 2 gliomas involve differentiated cells and can often be left untreated, or minimally treated, and have excellent survival rates, as serious cancers go. Stage 3 glioma normally involves astrocytes, and the disease is referred to as anaplastic astrocytoma. Stage 4 glioma is referred to as glioblastoma multiforme. The median survival for stage 3 glioma is 4 years (among UCSF patients) while the prognosis for stage 4 is 12 months or less.
The cell types involved are all glial cells, or non-neuronal cells that provide support and nutrition to neuronal cells. In the brain, Glial cells outnumber neurons by about 10 to 1. The main types of glial cells involved in cancer are epedymal cells, oligodendrocytes and astrocytes.
Glioma occurs when glial cells begin to divide in a more or less wildly uncontrolled manner, creating a dense fibrous mass of living and dead cells referred to as a lesion. Symptoms - which can include seizures, headaches, nausea, neurological or cognitive impairment - are caused by the tumor’s infiltration of important brain centers. Symptoms depend sensitively on the location of the tumor and can very greatly in degree.
The most common treatments for glioma are surgery, both by conventional and the newer ‘cyberknife’ procedures, radiation therapy (normally 3-dimensional conformal radiotherapy) and chemotherapy with the drugs temozolomide and more recently, with angiogenic blockers like bevacizumab. Surgery is not an option if the tumor is close to, or has infiltrated, motor or cognitive centers. Glioma is pernicious: even tumors that are surgically removed always grow back.
– Chris Gulker, July 2008