Hypertension and risk of brain metastasis from small cell lung cancer: A retrospective follow-up study

Background: Although metastatic brain cancer is one of the most common forms of cancer, little is known about the factors associated with its development. We examined the hypothesis that hypertension may increase the risk for brain metastasis (BM) in patients with primary small cell lung cancer (SCLC). Materials and Methods: A retrospective review of medical charts of patients diagnosed with SCLC between June, 1986 and June, 2003 at MeritCare in Fargo, ND, USA, was done to determine which of these patients subsequently developed brain metastases. The effects of hypertension, age, gender, body mass index and the site of SCLC on the risk of developing BM were examined using both univariate and multivariable Cox proportional-hazards regression models. Two-way interactions between hypertension and other covariates were also included in the analyses. Results: Two hundred and thirty-two patients were identified with SCLC and 185 patients were eligible for this study. Eighty-five (45.9%) patients developed BM. Over 54% of SCLC occurred in the right lobe and more than 70% of the patients with BM had them in multiple locations. The risk of BM is significantly higher in younger patients (p-value < 0.03). Univariate analysis showed a hazard ratio (HR) for hypertension of 1.01 (95% Confidence Interval (CI) 0.6-1.6) for BM from SCLC. The multivariable Cox model showed an adjusted HR for hypertension of 1.06 (95%CI 0.7-1.6) for BM from SCLC. Conclusion: As has been consistently observed for other lung cancers, SCLC is more common in the right lung. The higher incidence of BM in younger patients suggests that more aggressive therapy is needed in these patients. Hypertension does not appear to increase the risk of BM from SCLC.