Anaplastic Astrocytoma (AA) is a rare type of malignant brain tumor. As per World Health Organization (WHO) grading system, AA is classified Grade III astrocytomas. Grade I and II astrocytomas are nonmalignant whereas grade III and IV are malignant. There is a high possibility of lower grade astrocytomas changing into higher ones with passing time. AA develops from the special type of star-shaped brain cells called astrocytes. The manifestation of disease can vary depending upon the specific location and size of the tumor. The exact cause of AA is still unknown. However, researchers hypothesize that genetic and immunologic abnormalities along with environmental factors such as exposure to ultraviolet rays, certain chemicals, ionizing radiation can contribute to the progression of this disease.
High-grade brain tumors including Glioblastomas and Anaplastic Astrocytomas (AA) are the most common types of brain tumors diagnosed in the USA. The incidence and relative survival for AA have changed a little over the past two decades.
For the USA, The overall incidence of AA is reported to be nearly 0.48 per 100 000 person/years per million person/years and 5- and 10-year relative survival rates of populations is approximately 23.6% and 15.1%, respectively. The incidence rate is very less in comparison to Glioblastoma Multiforme (GBM) projecting it as a rare form. There is slightly male dominance in this indication with a ratio of 1.28 (M: F).
However, the incidence rates for the young age group do not differ by sex but there is a significant increase in the rates for the adult age group. The increase in the incidence rate is observed to be more in white males, almost four times than that of black males. The incidence is less in children and usually develop between 5 and 9 years of age.
Treatment paradigm of AA includes surgery, radiation, and chemotherapy. These treatment options can be used alone or in combination with one another. Till date, only one chemotherapeutic agent has been approved for adults with anaplastic astrocytoma. It's notable that no agents have been approved for pediatric patients. Research is ongoing for the same. A variety of new therapies are under investigation which involves several classes of drugs including protein kinase inhibitors, biological response modifiers, and angiogenesis inhibitors. However, the pipeline is not that promising with very limited potential candidates in clinical studies. Most of the patients experience disease progression post initial treatment. The therapeutic options for later stages have shown limited efficacy contributing to poor survival rate. There remains a high unmet need for AA patients.