Within the first month following a first-time evaluation for a psychiatric symptom, Danish researchers found that the odds of being diagnosed with any type of malignancy were increased 2.61-fold. But for brain tumors, the incidence rate ratio was increased almost 19-fold.
"Our study illustrates the importance of making a thorough physical examination of patients with first-time psychiatric symptoms," said lead author Michael E. Benros, MD, from the University of Aarhus, in Denmark, and the Danish Cancer Society. "The overall cancer incidence was highest in persons older than 50 years of age admitted with a first-time mood disorder, where 1 out of 54 patients would have a malignant cancer diagnosed within the first year."
The highest risk was concentrated in the range of 50 to 64 years of age, he told Medscape Oncology. "The overall incidence of cancer was increased almost 4-fold and the incidence of brain tumors was increased 37 times."
Dr. Benros also noted that paraneoplastic neurological disorders have previously been reported in patients who subsequently were found to have small-cell lung cancer. "But our study is the first to indicate that this is also the case with psychiatric symptoms, where patients with SCLC had the highest incidence after patients with brain tumors," he said.
It is hypothesized that paraneoplastic neurological disorders are most often induced in patients with SCLC, as well as in non-SCLC but with less frequency, because patients with SCLC produce antibodies that react with both the tumor antigens and the nervous system, explained Dr. Benros. This is turn might induce both the paraneoplastic neurological disorders and the psychiatric symptoms.
"The etiology of paraneoplastic psychiatric disorders is also partly explained by the fact that lung cancer, especially SCLC, tends to have the highest risk of metastasis to the brain," he added. "These metastases could then induce psychiatric symptoms by direct pressure. SCLC can also stimulate ectopic hormone production, which might then induce psychiatric symptoms, but our study cannot provide any evidence regarding causal mechanisms."
High Incidence of Brain Tumors and Lung Cancer
In their study, Dr. Benros and colleagues investigated the possibility that psychiatric symptoms could be caused by an undetected malignancy or be part of a paraneoplastic syndrome. Using data from the Danish Psychiatric Central Register and the Danish Cancer Registry, the researchers evaluated the occurrence of psychiatric symptoms and cancer in 4,320,623 million individuals who were followed in the 10-year period from 1994 to 2003. During this time, 202,144 persons had a first-time psychiatric contact and 208,995 were diagnosed with cancer.
From 1994 to 2003, a total of 4132 persons had a first-time psychiatric in- or outpatient contact and were subsequently diagnosed with cancer. Of this group, 1267 patients were diagnosed with cancer within the first year following their first-time psychiatric contact, and within this cohort, 145 persons had primary brain tumors.
The team observed that there was an increased overall incidence rate ratio of cancer during the initial 3-month period following a first-time psychiatric contact. During the first month, the incidence rate ratio of overall cancer was 2.61 (95% CI, 2.31 – 2.95), for brain tumors 18.85 (95% CI, 14.52 – 24.48), and for lung cancer 2.98 (95% CI, 2.16 – 4.12). The specific incidence rate ratio for SCLC was 6.13 (95% CI, 3.39 – 11.07).
In general, the increased incidence rates for most cancers decreased to a nonsignificant level within the first 3 months. The exception was for brain tumors, for which the incidence rate ratio remained significantly elevated during the first 9 months following a first-time psychiatric contact.
"Future studies should address a possible screening of subgroups of psychiatric patients with first-time symptoms," said Dr. Benros. "Psychiatric disorders with onset after the age of 50 could be an indication for brain imaging and, if they are smokers, patients could be examined for antibodies such as anti-Hu, but a more formal analysis of costs and benefits was beyond the scope of our study."
Source : http://www.medscape.com/viewarticle/705450?src=mpnews&spon=34&uac=133298AG
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