PCI linked to better OS in patients with extensive stage SCLC and no brain metastasis
Patients with extensive stage small cell lung cancer (ES-SCLC) without brain metastasis who underwent prophylactic cranial irradiation (PCI) after achieving stable disease or better on first-line chemotherapy had improved overall survival (OS) compared with those who did not undergo PCI, according to a retrospective study from Singapore.
Of the 224 patients diagnosed with ES-SCLC without brain metastasis between 2003 and 2010, 71 had stable disease or better following first-line chemotherapy. They received doses/fractions of PCI ranging from 25 Gy in 10 fractions, 30 Gy in 10 fractions, to 30.6 Gy in 17 fractions as well as palliative thoracic radiation therapy in doses/fractions ranging from 20 Gy in 5 fractions, 30 Gy in 10 fractions, 36 Gy in 12 fractions, to 40 Gy in 16 fractions.
The use of PCI among patients with stable disease or better following first-line chemotherapy rose from 10 percent between the years 2003 and 2006 to 32 percent between 2007 and 2010 (p=0.044). The likelihood of receiving second-line chemotherapy also increased between the 2003–2006 period and the 2007–2010 period (17 percent vs 49 percent; p=0.005). However, OS rates did not significantly differ between the time frames (p=0.144).
Among patients who had undergone brain imaging at diagnosis, those who underwent PCI demonstrated improved OS compared with those who did not undergo PCI (hazard ratio [HR], 0.11, 95 percent confidence interval [CI], 0.04–0.32; p<0.001). [Radiat Oncol 2018;13:247]
Other factors that led to improvement in OS were receipt of thoracic radiation (HR, 0.47, 95 percent CI, 0.22–0.98; p=0.045) or whole brain radiation (HR, 0.18, 95 percent CI, 0.08–0.43; p<0.001), and receipt of more cycles of first-line chemotherapy (4–6 vs 1–3; HR, 0.31, 95 percent CI, 0.12–0.83; p=0.020).
Undergoing brain imaging at diagnosis was not compulsory in this trial. As such, one potential reason behind the greater OS in PCI recipients could be the early treatment of existing intracranial micrometastases which would not have been treated in patients who did not undergo PCI, said the researchers.
The findings of the present study are similar to that of a study conducted in the European population by the European Organization for Research and Treatment of Cancer (EORTC) which found an improved OS rate among patients with ES-SCLC who received PCI after responding to first-line chemotherapy. [N Engl J Med 2007;357:664-672] However, they contradict that of a randomized trial conducted in the Japanese population which found no improvement in OS following this treatment as compared with regular surveillance (every 3 months) with magnetic resonance imaging (MRI). [Lancet Oncol 2017;18:663-671]
“[The results of the present study] suggest that the results of the EORTC trial are reproducible in the real-world setting particularly when MRI brain imaging was not routinely used for evaluation of the intracranial disease,” said the researchers.
“In clinical situations where patients with ES-SCLC with at least stable disease post-initial chemotherapy decline regular active MRI brain imaging surveillance, PCI should be recommended,” they said.