Age-Related Prognosis in Benign Astrocytoma
May 1, 1999
Age-Related Prognosis in Benign Astrocytoma
abstract & commentary
Source: Shafqat S, et al. Age-dependent rate of anaplastic transformation in low-grade astrocytoma. Neurology 1999; 52:867-869.
It’s well known that the prognosis of fibrillary astrocytomas depends significantly on patients’ ages and the histopathologic interpretation of their tissue. Shafqat and colleagues cite sources indicating that the incidence of low-grade astrocytomas maximizes at about 34 years of age, whereas anaplastic astrocytomas top at about 41 years of age and glioblastomas at about 53 years of age. Against this background, they suggest that age of onset importantly influences both the initial form of these tumors and their resistance to future anaplasia.
From a cohort of 276 patients biopsied at Mass General Hospital [MGH] between 1981-1995, the records of 24 cases fulfilled the following: 1) all had low-grade fibrillary astrocytomas, free of oligodendroglia; 2) the tumor occupied a single cerebral hemisphere; 3) tumors were biopsied within six months after first symptom; and 4) all tumors transformed into high-grade, malignant glioma judged by either second biopsy (n = 14) or clinical/imaging signs (10).
As expected, time from initial biopsy of fibrillary astrocytoma to convert to malignant anaplasia shortened as the age of first symptoms increased. Shafqat et al present a table and scatter plot diagram identifying each patient’s age of onset and malignant transformation of the tumor. Specific breakdowns of risk into ages were consistent with the literature. Seven patients younger than 25 at onset had a 49-month average between first diagnosis of malignancy and a total of 60 months from first diagnosis until death. Those aged from 25-44 years at onset averaged 49 months to transformation and 43 months until death; nine patients older than 44 at onset averaged 7.6 months to develop anaplasia and on average died at 13.6 months after first biopsy. Out of the 24 reported patients, four have survived: three younger than 45 years, and one older.
Commentary
This report provides useful information about the lifetime biology of nonanaplastic fibrillary astrocytomas. I, however, find two omissions that would increase the value of the report. One is that only patients whose tumors have undergone anaplastic regrowth are cited. Neurology Alert wishes that all cases of fibrillary astrocytomas from MGH, including those who have not transformed, would likely have identified a larger cohort of patients. This would possibly have strengthened survival statistics of the younger than 45 years of age cohort, thereby improving possible prognoses to patients and families. I can recall two patients who first suffered a low-grade, resected astrocytoma during their early 20s, then remained disease-free until their late 50s. At that time, they developed fatal glioblastomas in the same areas occupied by their previous astrocytomas.
A second comment has to do with Shafqat et al’s printed scattergraph, here modified by Neurology Alerts placing of a perpendicular line to divide the independent ages and prognoses of two clusters. The P value given in the upper right quarter describes Shafqat et al’s original linear values of age/transformation as calculated by a Pearson correlation coefficient. A quick glance, however, indicates no overlapping of patients between Cluster 1 and Cluster 2 in years of onset, and of time from initial diagnosis to malignant development. Our accompanying table illustrates that the average patient in Cluster 2 showed a six-fold rapidity between the first diagnosis of astrocytoma and transformation into anaplastic malignancy. Time to death in Cluster 2 patients was one-fourth that of Cluster 1 [ P < 0.01-6 ANOVA].
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content