Paroxetine may cause increase in carcinoebmryonic antigen (CEA)

IntroductionCarcinoebmryonic antigen (CEA) is mostly used to detectearly recurrences after surgery in patients with colorectalcancer [1]. In this report, we present a case in whichparoxetine use caused increase in CEA. In literature, asimilar case has not been previously presented.CaseA 61-year-old male patient, married, with a child, sufferedtwo depressive episodes, with the first one occurring 15years ago and the second one 7.5 years ago. After thesecond episode, he received paroxetine treatment for ayear, but 6 months after the cessation of treatment, a thirddepressive episode occurred, and paroxetine was startedagain at 20 mg/day. After a response was obtained, hecontinued to use 10 mg/day. Six years after the lastepisode, in routine controls, CEA levels began to increase.CEA level was 20 in April 2008, 27 in June 2008 and 34in September 2008. A whole-body cancer screening wasperformed. However, clinical examination and laboratorytests [computed tomography (CT) and ultrasound (US)]did not reveal cancer. Therefore, in this patient, theincrease in CEA was attributed to paroxetine, and thetreatment was discontinued. A month later, CEA levelbecame 17.DiscussionCEA increase during paroxetine use may be related to theincrease in serotonin, serotonin