Comparison of the Effectiveness of “Late” and “Early” Prophylactic Cranial Irradiation in Patients with Limited-Stage Small Cell Lung Cancer

Abstract

To evaluate the effectiveness of timing of application of prophylactic cranial irradiation (PCI) in patients with small cell lung cancer in limited stage of disease (LS SCLC). Between 1995 and 2004, 129 patients with LS SCLC were treated within two consecutive phase II studies assessing different schedules of combined treatment. All patients received chemotherapy and concurrent thoracic radiotherapy. In 86 patients (66.7%) who developed complete response in the thorax, PCI was performed either after chemoradiotherapy ("late" PCI , n = 45 [52.4%]) or during chemoradiotherapy ("early" PCI, n = 41 [47.7%]). In the latter case, PCI was given immediately after the end of thoracic radiotherapy and prior to the last cycles of chemotherapy to a total dose of 30 Gy in 2-Gy fractions to the whole brain. The results were evaluated with regard to 4-year rates of overall survival, disease-free survival, and brain metastases-free survival. Additionally, the prognostic role of PCI application and its time delay in relation to survival rates and incidence of brain metastases was estimated. The 4-year survival rates were 25.5% for overall survival, 26.8% for disease-free survival, and 67.8% for brain metastases-free survival. During the observation period, 32 patients (24.8%) developed brain metastases, which occurred in 20 of 43 patients (46.5%) without and only in twelve out of 86 patients (14%) with PCI. The 4-year brain metastases-free survival rates were 81.8%, if PCI was applied, versus 32.2%, if no such procedure was used (for p = 0.0000). The timing of PCI appeared to be an important factor in terms of decreasing the incidence of brain metastases. PCI significantly decreases the incidence of brain metastases and delays their development in patients with LS SCLC. "Early" PCI is more effective than PCI applied after combined therapy.