Seasonal variability in the incidence of carcinomatous meningitis.

ABSTRACT

OBJECT The aim of the study was to investigate whether there are seasonal differences in the occurrence of carcinomatous meningitis (CM), with a greater prevalence of the disease in months with higher temperatures. METHODS: The authors searched the records of all patients with a diagnosis of CM from 1998 until 2013 at the University Hospital of Patras, Greece. The date of hospitalization was extracted for each patient. The cases were divided into 2 categories depending on the time of CM diagnosis. Based on the official data regarding the annual temperature distribution in this region, the authors divided the patients into 2 groups. The first group consisted of cases diagnosed with CM from October 15 to April 15 (cold climate and shorter daytime duration), whereas the second group comprised patients diagnosed between April 15 and October 15 (warm climate and longer daytime duration). RESULTS: Overall, 44 confirmed cases of CM were found. The most common type of malignancy associated with the development of CM was breast cancer (27 patients), while the second most common tumor was lung carcinoma (11 patients). The median interval between the time of initial cancer diagnosis and CM was 4.5 years. Thirty-one patients were diagnosed with CM during the period between April 15 and October 15, while the remaining 13 patients developed CM between October 15 and April 15, a significant difference (p = 0.01). CONCLUSIONS: Significantly more patients developed CM during the warm season of the year. To the authors' knowledge, this is the first study to provide evidence for the potential seasonal variability in CM incidence. However, these results should be validated prospectively in larger cohorts.