Extrathymic malignancies in thymoma patients with and without myasthenia gravis.
OBJECTIVE
The influence of myasthenia gravis (MG) on risk of cancer is uncertain. Using nationwide, comprehensive data, we investigated the association between MG and occurrence of extrathymic malignancies in thymoma patients, and also assessed the risk of consecutive extrathymic malignancies after thymoma diagnosis.


METHODS
Two hundred twelve thymoma patients were identified at the Cancer Registry of Norway between 1969 and 2005. Records on all extrathymic malignancies for these patients were supplied from the Registry's database. Comparisons were made between MG and non-MG patients and between thymoma patients and the general population.


RESULTS
The frequency of extrathymic malignancies was similar in MG and non-MG thymoma patients, and so was the survival after thymoma diagnosis. Extrathymic malignancies occurred in 10% of thymoma patients within 10 years following the thymoma diagnosis. Thymoma patients had a significantly increased risk of developing an extrathymic malignancy compared to the general population. This was not linked to any specific kind of cancer. Thymoma morphology was not a significant predictor for an increased risk of consecutive cancer.


CONCLUSIONS
The immunological process underlying MG does not influence the risk of cancer in thymoma patients. Thymoma patients have a significantly increased risk of extrathymic malignancies. This is an intrinsic effect, being unaffected by a coexisting autoimmune disease such as MG and not specific for any type of cancer. Screening for extrathymic malignancies in thymoma patients is probably not recommendable, but clinicians should be aware of the high rate of extrathymic malignancies occurring in thymoma patients.
Owe
Jone Furlund
JF
Department of Clinical Medicine, University of Bergen, Norway. jone.furlund.owe@helse-bergen.no
Cvancarova
Milada
M
Romi
Fredrik
F
Gilhus
Nils Erik
NE
D017677:Age Distribution; D017668:Age of Onset; D002423:Cause of Death; D015897:Comorbidity; D006801:Humans; D007107:Immune System / Q000503:physiopathology; D016867:Immunocompromised Host / Q000276:immunology; D007166:Immunosuppressive Agents / Q000009:adverse effects; D015994:Incidence; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000188:drug therapy / Q000276:immunology / Q000401:mortality*; D009369:Neoplasms / Q000276:immunology / Q000401:mortality*; D009664:Norway / Q000453:epidemiology; D011159:Population Surveillance; D011379:Prognosis; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D015996:Survival Rate; D013945:Thymoma / Q000188:drug therapy / Q000276:immunology / Q000401:mortality*; D015854:Up-Regulation / Q000276:immunology
D007166:Immunosuppressive Agents