Perhaps contrary to expectations, the presence of an oligodendroglial
component in patients with anaplastic astrocytomas was associated with
a significantly longer survival than were pure anaplastic tumors. This
finding emerged from a randomized phase I-II trial from the Radiation Therapy
Oncology Group (RTOG).
In this study, Dr. Bernadine Donahue of New York University, and colleagues
reviewed the data on 133 adults who met the criteria defined for an anaplastic
astrocytoma: the absence of tumor necrosis with the presence of two or
more of the following features: nucleopleomorphism, increased cell density,
mitotic figures, or vascular prominence. Of these patients, 24 were considered
to have oligodendroglial elements.
There was a marginally significant difference in age, with patients
who had oligodendroglial elements being slightly older than patients with
pure anaplastic astrocytomas. Patients with oligodendroglial elements were
also more likely to have had resection than biopsy. Although there was
no difference in the performance status or neurologic function status between
the patients with pure anaplastic astrocytomas and the patients who had
anaplastic astrocytomas with oligodendroglial components, there was a significant
difference in survival: the median survival of patients with pure anaplastic
astrocytomas was 3 years vs 7.3 years for patients who had anaplastic astrocytomas
with oligodendroglial elements.