First-time seizures a warning signal for cancers

First-time seizures appear to be associated with increased short-term and long-term risks of cancer, according to a population-based cohort study.

Researchers used nationwide Danish medical registries and identified adults with a first-time hospital diagnosis of seizure and no preceding cancer. They evaluated the risk of neurological and non-neurological cancers as well as site-specific cancer within 1 year, from 1 to <5 years, and from 5–20 years after the first seizure.

The analysis included 49,894 adults with first-time seizure (median age at seizure diagnosis 51.5 years, 41.4 percent female). Within the first year of follow-up, 1,172 neurological and 850 non-neurological cancers occurred.

For the subsequent follow-ups, 87 neurological and 1,226 non-neurological cancers were reported during the period from 1 to <5 years, and 112 neurological and 2,120 non-neurological cancers during the period from 5 to 20 years.

For any cancer, the absolute risks (ARs) were 4.1 percent within 1 year, 3.5 percent from 1 to <5 years, and 13.4 percent from 5 to 20 years. The corresponding standardized incidence ratios (SIRs) were 5.30 (95 percent CI, 5.07–5.54), 1.18 (95 percent CI, 1.12–1.25), and 1.34 (95 percent CI, 1.28–1.40).

For neurological cancers, the ARs were 2.4 percent, 0.2 percent, and 0.7 percent, with SIRs of 76.1 (95 percent CI, 71.8–80.6), 1.85 (95 percent CI, 1.48–2.28), and 1.46 (95 percent CI, 1.20–1.75) within 1 year, from 1 to <5 years, and from 5 to 20 years of follow-up, respectively. For non-neurological cancers, the ARs were 1.7 percent, 3.3 percent, and 12.8 percent, with SIRs of 2.32 (95 percent CI, 2.17–2.48), 1.15 (95 percent CI, 1.09–1.22), and 1.33 (95 percent CI, 1.28–1.39), respectively.