Follow-up neurological evaluation in patients with small cell lung carcinoma treated with prophylactic cranial irradiation and chemotherapy

The safety of prophylactic cranial irradiation (PCI) has recently been questioned, based on reports of computerized tomographic abnormalities mainly seen in children, who received PCI and chemotherapy, primarily for acute lympbocytic leukemia. In order to clarify the significance of these findings, we examined a series of adult patients who were long term survivors (18-48 months, median 26 months, after all treatment). These patients were treated with combination radiotherapy and chemotherapy for small cell lung carcinoma and received cranial irradiation in the absence of known brain involvement by tumor. Patients were divided into three groups: three patients who received PCI + intrathecal metbotrexate (MTX) (Group 1), and ten who received only PCI (Group 2). An additional three patients (Group 3) were identified as long term survivors (41-70 months after all treatments) of a similar treatment program without any central nervous system (CNS) prophylaxis. All patients received an extensive evaluation of a variety of clinical parameters, EEG, and computer tomography (CT). Although CT abnormalities were detectable (mild cerebral atrophy in eight patients, encephaiomalacia in one of the 13 patients with CNS prophylaxis, and wild atrophy in two of the three patients without CNS prophylaxis~ so significant clinical abnormalities or EEG changes were detectable. While this group of patients is small, it is a unique cohort: adults who have received cranial irradiation in the absence of known brain tumor with long term follow-up. The precise role of CNS prophylaxis in the etiology of CT abnormalities is unclear, and the lack of clinically significant changes would suggest no contraindication to PCI when indicated.