First-Time Seizures may be Potential Marker of Underlying Cancer: Study
Researchers have found in a large Danish study involving 50,000 patients that first-time seizures are associated with a significantly increased risk of both neurologic and non-neurologic cancers within one year and beyond. Compared to the general population, the standardized incidence ratio was markedly elevated at 76.1 for neurologic cancers and 2.32 for non-neurologic cancers. These findings suggest that a first seizure may serve as an early clinical indicator of occult malignancy, particularly in cases of metastatic or advanced disease. The study was published in JAMA Neurology by Andreas L. P. and colleagues.
The community-based study involved 49,894 adults who had a median age of 51.5 years (interquartile range [IQR], 35.6-67.8). Of this population, 41.4% (20,648) comprised females. The researchers employed the powerful Danish registry system to track their subjects either until they were diagnosed with cancer (not nonmelanoma skin cancer), died, or left the country. The team then determined the incidence of cancer in these individuals relative to that in the overall Danish population, enabling them to estimate the SIRs for various time frames: within a year, between one and five years, and between five and 20 years following the seizure.
Key findings:
- During the first year of follow-up, 1,172 neurological cancers and 850 nonneurological cancers were reported.
- Any type of cancer had a very high AR of 4.1% during the first year, with an extremely high SIR of 5.30 (95% CI, 5.07-5.54) relative to the general population.
- For neurological cancers, there was a remarkably high SIR of 76.1 (95% CI, 71.8-80.6) during the first 12 months.
- Also, for nonneurological cancers, an increased risk of 2.32 (95% CI, 2.17-2.48) was seen during the first 12 months.
- The risks decreased and became stable over the next years.
- From year 1 through 5, there was a risk of 1.18 (95% CI, 1.12-1.25), whereas from 5 through 20 years, the risk increased to 1.34 (95% CI, 1.28-1.40).
- During the longest follow-up period, the risk of any type of cancer increased to 13.4%, including a risk of 12.8% of nonneurological cancer with an AR of 12.8% and an SIR of 1.33.
The results of this national study indicate that new-onset seizures are a significant indicator of hidden cancer, especially during the initial year following the occurrence of seizures. Such results emphasize the need to conduct comprehensive evaluations on patients who have experienced their first seizure. These patients need to be screened for not only brain cancers but also for non-brain cancers. The high risk of cancer occurrence in the short-term period and the slight risk in the long-term period require ongoing medical attention to these patients.
Reference:
Pedersen AL, Farkas DK, Fuglsang CH, et al. Risk of Cancer in Patients With First-Time Seizure. JAMA Neurol. Published online April 27, 2026. doi:10.1001/jamaneurol.2026.0894
