Chemotherapy in adult patients with pilocytic astrocytoma: a retrospective multicenter cohort study

Pilocytic astrocytomas are circumscribed WHO grade I gliomas that predominantly affect children, although they also occur in adults. While maximal safe resection is standard treatment, until recently chemotherapy was often used in pediatrics with irresectable symptomatic tumors to delay radiotherapy. As evidence for this approach in adults is limited, we performed a multicenter retrospective cohort study on this subject.

Adult patients (≥ 16 years) treated with chemotherapy between 2006 and 2020 across eight Dutch medical centers were included. Treatment response was centrally assessed using RAPNO criteria and survival outcomes were analyzed using the Kaplan-Meier method.

Thirty-one patients with pilocytic astrocytoma were included (median age 27 years). Most patients had received prior treatments, including radiotherapy (n = 19) and/or surgery (n = 17), with a median interval of over five years from histopathological diagnosis to the start of chemotherapy. Temozolomide was most frequently used (64.5%). The objective response rate for all types of chemotherapy was 42%, with a median progression-free survival of 20 months and a median overall survival of 49 months. Adolescents and young adults (< 40 years) showed significantly better survival outcomes.

Chemotherapy offers meaningful disease control in adolescents and young adults with irresectable symptomatic pilocytic astrocytoma, after prior treatments. However, with the improved efficacy and tolerability of targeted treatments, such as BRAF/MEK inhibitors, treatment is shifting away from traditional chemotherapy and radiotherapy. Nevertheless, chemotherapy may still represent a viable treatment option in adolescent and young adults when no actionable molecular targets are identified or when targeted therapies have failed.