What is brain tumor- Brain tumors are known to be notorious and dreaded ailment among human being since ancient period. Ancient literature shows that this entity was known then but most of these tumors were diagnosed at post-mortem. The situation remained same till 20 th century when development of imaging and other diagnostic modalities helped us to know much about brain tumors, its diagnosis and timely intervention. Till date, a lot of research work has been done over brain tumors to know its pathogenesis, genetic causes and targeted therapies but still many questions are unanswered. Most important part is that despite of advances in
treatment modalities, brain tumors remains one of the dangerous illnesses in terms of both mortality and morbidity.
Brain tumors can be divided into primary and secondary. Primary brain tumors arise in brain itself while secondary tumors are metastasis from malignancies of other body parts. Primary brain tumors are rare as compared to other cancers of body. Although it constitutes about 1 – 2% of total cancers but is responsible for about 20% deaths due to cancer related causes. In India, the incidence is about 2/10000 people. Primary brain tumors are both benign and malignant. About 33% of primary brain tumors are malignant. No age group is spared from brain tumors. It affects all from pediatric age group to elderly patients. The incidence among various age groups is different according to type of tumor. Sex ratio is also variable according to type of tumors. In nutshell, no age group or sex is immune to brain tumors.
Previously brain tumors were classified according to histogenesis and similarities with different putative cells of origin and their presumed level of differentiation (WHO classification 2007) like glioma, meningioma, pituitary tumor, medulloblastoma, ependymoma, chordoma etc. But latest WHO classification 2016 breaks the principle of diagnosis based only on microscopy and incorporates the molecular parameters in classification.