Natural course and therapeutic indication of incidentally discovered brain tumors

Abstract

Intracranial tumors such as meningiomas, vestibular schwannomas and pituitary adenomas are often found incidentally because of the increased specificity of image‒based diagnosis especially in the advanced countries. However, we do not know exactly the natural history and growth rates of these tumors, and it could sometimes be difficult to decide the indication of therapy, as well as when/how to treat them. In this paper, the natural history and growth rates of incidentally discovered meningiomas (IDMs) are summarized using the published papers in order to afford a better perspective into these tumorsʼ genesis. Also, the growth patterns of IDMs recently revealed mathematically by some reports are introduced, to discuss the indication and timing of therapy of IDMs. Likewise, for vestibular schwannomas, the natural history and growth rates are described, as well as the relatively complex issues involved in considering therapy indication such as tumor size/location, surgical approach, hearing/facial preservation and the indication of stereotactic radiosurgery (SRS). Finally, the natural history of incidentally discovered pituitary adenomas (pituitary incidentaloma) is shown with a guideline used in Japan, to achieve a better understanding of therapeutic indication and timing.