Neurocysticercosis among patients with cerebral gliomas.

BACKGROUND: Parasites have been implicated in the pathogenesis of human cancer. Anecdotal reports have suggested an association between neurocysticercosis and brain tumors.
OBJECTIVE: To determine whether neurocysticercosis is a risk factor for cerebral glioma.
DESIGN: Case-control study.
SETTING: A university general hospital and a cancer referral center. PATIENTS: Forty-three consecutive patients with a cerebral glioma and 172 controls matched for age, sex, and socioeconomic status.
METHODS: We determined the ratio between the frequency of neurocysticercosis in patients with a cerebral glioma and in matched controls. We also evaluated differences in the characteristics of the patients and in the histological type of the neoplasm among case patients with and without neurocysticercosis. In addition, we noted relationships between the location of the cerebral glioma and that of parasitic lesions.
RESULTS: Eight (16.8%) of 43 patients with a glioma and 5 (2.9%) of 172 controls had neurocysticercosis (P < .001). The odds ratio for this association was 7.63 (95% confidence interval, 2.03-31.09). Patients with glioma and neurocysticercosis were older than those without neurocysticercosis (mean [+/-SD] age, 62.75 +/- 18.34 years vs 44.69 +/- 14.04 years; P = .02). Glioblastoma multiforme was more frequent among case patients with neurocysticercosis than among those without neurocysticercosis (87.5% vs 48.6%); however, this difference was not statistically significant (P = .24). Six of the 8 patients with neurocysticercosis and a cerebral glioma had calcified parasitic lesions within and around the tumor.
CONCLUSIONS: Results from this study suggest that neurocysticercosis is a risk factor for cerebral glioma. The intense astrocytic gliosis that surrounds calcified cysticerci, together with the suppression of the cellular immune response induced by cysticerci, may contribute to the development of malignant glial cells in patients with neurocysticercosis.