Primary brain tumours as second primary: a novel association between meningioma and colorectal cancer

In a previous study, a decreased risk for first degree relatives of patients with astrocytoma has been observed for breast and colorectal cancer. The aim of this study was to examine the associations between breast and colorectal cancer as first primary cancer and the risk of developing astrocytoma and meningioma as a second primary cancer. Two cohorts were constructed, one from all cases with breast cancer (1,036,466 person-years) and one from all cases of colorectal cancer (572,422 person-years) in Sweden during the period 1958-1994. The risk of developing astrocytoma and meningioma after breast or colorectal cancer was calculated. A significant increased risk for developing meningioma was seen after colorectal cancer, standardized incidence ratio (SIR) 1.60 confidence interval (CI; 1.32-1.94) and after breast cancer, SIR 1. 57 CI (1.36-1.81). The previously observed decreased risk for astrocytoma could not be verified in this study. A novel association between meningioma and colorectal cancer, particularly in females, was observed, which justifies further studies to evaluate common aetiological factors.