Syncope as a sign of occult cancers: a population-based cohort study

Abstract

Background We examined if syncope was a marker of an occult cancer by comparing the risk in patients with a syncope episode with that of the general population. Methods Using Danish population-based medical registries, we identified all patients diagnosed with syncope during 1994–2013 and followed them until a cancer diagnosis, emigration, death or end of follow-up, whichever came first. We computed cumulative risks and standardised incidence ratios (SIR) with 95% confidence intervals (CI). Results Among 208,361 patients with syncope, 20,278 subsequent cancers were observed. The 6-month cumulative risk of any cancer was 1.2%, increasing to 17.9 % for 1–20 years of follow-up. The highest cumulative risks after 6 months of follow-up were lung cancer (0.2%), colorectal cancer (0.2%), prostate cancer (0.1%) and brain cancer (0.1%). The 6-month SIR were 2.7 (95% CI: 2.4–3.0) for lung cancer, 2.0 (95% CI: 1.8–2.2) for colorectal cancer, 1.7 (95% CI: 1.5–1.9) for prostate cancer and 10.0 (95% CI: 8.6–11.4) for brain cancer. Conclusions Syncope was a weak marker of an occult cancer. In short-term the highest cumulative risks were observed for lung, colorectal, prostate and brain cancers. An aggressive search for occult cancer in a patient with syncope is probably not warranted.

Association between Syncope and the 6-Month Incidence of Ischemic Stroke, Arrhythmia, Brain Tumor, Epilepsy, and Anxiety Disorder

“…Only slightly more than one in a thousand patients in the group with syncope were diagnosed with a brain tumor in the 6-month period, and this figure was even lower than one in three thousand in the group without syncope. These results are consistent with the findings of Lorenzen et al, who's large population-based cohort study investigated whether syncope was a marker for hidden cancer, showing an increased but relatively low cumulative risk of brain tumor over a six-month period for a cohort of syncope patients [20].…”

“…As possible mechanisms of an association between brain tumors and syncope, the authors of the study identified, among other factors, compression of blood vessels, infiltration of the vagus and glossopharyngeal nerves, and infiltration of the brain areas relevant for cardiovascular functions, as well as tumor-induced anemia and tumor-induced venous thromboembolism, all of which can cause cerebral hypoperfusion and, thus, result in syncope [ 20 ]. Furthermore, the association between syncope and brain tumor diagnosis was only significant in the age groups 61–70 years and >70 years.…”

“…However, it is known that syncope can occur as a symptom or early sign of a variety of medical conditions, such as brain tumors, cardiac arrhythmia, transient ischemic attack (TIA), and epilepsy [ 1 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], and can also be associated with a variety of psychiatric disorders, most notably depression and anxiety disorders [ 26 , 27 , 28 , 29 , 30 ].…”