We used brain radiotherapy as a surrogate for the presence of brain metastases in patients with non–small cell lung cancer (NSCLC) to determine the prevalence of brain metastases using the Surveillance Epidemiology and End Results database.
Patients with NSCLC diagnosed between 1988 and 1997 were subdivided according to brain radiotherapy status at presentation into: “none” or “radiation therapy indicated.” We calculated the frequency of brain radiotherapy use in all patients. Odds ratios (ORs) for the indication of brain radiotherapy were calculated for individual prespecified covariates of interest. All statistical tests were 2-sided and P<0.05 were considered significant.
At presentation, brain radiotherapy was indicated in 10,963 (8.3%) of the 131,456 patients diagnosed with NSCLC between 1988 and 1997. On multivariable analysis the following were significantly associated with brain radiotherapy use: age (OR, 0.653 per 10 y increase in age; 95% confidence interval [CI]: 0.642, 0.665); female sex (OR, 1.05; 95% CI: 1.01, 1.10]); adenocarcinoma histology (HR, 1.67; 95% CI: 1.58, 1.76) or large cell or other histology (OR, 1.67; 95% CI: 1.57, 1.77); tumor size>3 cm (3.1 to 5 cm OR, 1.22; 95% CI: 1.14, 1.30 and >5 cm OR, 1.25; 95% CI: 1.17, 1.33); tumor grade >II (grade III OR, 1.82; 95% CI: 1.69, 1.95 and grade IV OR, 1.91; 95% CI: 1.73, 2.11); and nodal involvement N1 (OR, 1.33; 95% CI: 1.20, 1.47), N2 (OR, 2.24; 95% CI: 2.10, 2.40), and N3 (OR, 2.39; 95% CI: 2.19, 2.60).
Brain radiotherapy is indicated in over 8% of patients with NSCLC at presentation. We demonstrated that the risk of brain metastasis at presentation may be stratified with the use of 6 clinical factors.
*Department of Internal Medicine, Division of Medical Oncology
†Division of Biostatistics
Departments of §Radiation Oncology
∥Pathology and Immunology
¶Surgery, Washington University School of Medicine, St. Louis, MO
‡Southwest Cancer Center, Orlando, FL
Supported by the National Cancer Institute of the National Institutes of Health (NIH), Grant Number 1K12CA167540 and the Clinical Translational Science Award (CTSA) program of the National Center for Advancing Translational Sciences at the National Institutes of Health, Grant Number UL1RR024992. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
S.N.W.: reports grants from Washington University Paul Calabresi K12 Career Development Award in Clinical Oncology, National Cancer Institute of the National Institutes of Health (NIH), Grant Number 1K12CA167540, grants from Clinical Translational Science Award (CTSA) program of the National Center for Advancing Translational Sciences at the National Institutes of Health, Grant Number UL1RR024992, during the conduct of the study; grants from Duke-UNC-Wash U partnership for early phase clinical trials in Cancer (UM1 CA186704-02), outside the submitted work. C.G.R.: reports grants from Varian Medical Systems, outside the submitted work. R.G.: reports consultancy honoraria from the following entities: Boehringer Ingelheim, GlaxoSmithKline, Bayer, Celgene, Roche/Genentech, Clovis, Helsinn, AbbVie, Merck, Pfizer, outside the submitted work. D.M. reports that he is on the advisory board for Genentech and Celgene and a Speaker for Boehringer Ingelheim, outside of submitted work. The remaining authors declare no conflicts of interest.
Reprints: Daniel Morgensztern, MD, Division of Oncology, Washington University School of Medicine, 660S. Euclid, P.O. Box 8056, St Louis, MO 63110. E-mail: firstname.lastname@example.org.