Dual TMPRSS2:ERG Fusion in a Patient with Lung and Prostate Cancers

The TMPRSS2:ERG fusion is considered prostate specific and has been rarely described in other tumors. We describe the case of a patient who developed lung and prostate cancers, both harboring the TMPRSS2:ERG fusion. The patient developed a cancer of the prostate with lymph node metastases and after two years a nodule of the thoracic wall. The histology and immunohistochemical profile of the two tumors were typical of prostate and lung cancers. The presence of the TMPRSS2:ERG fusion was demonstrated by next-generation sequencing on both malignancies, leading to the assumption that the lung nodule was a metastasis from the prostate cancer. The patient failed to respond to antiandrogen therapy, while chemotherapy for lung cancer led to a significant objective response. To our knowledge, this is the first case of a lung cancer harboring the TMPRSS2:ERG fusion, widening the spectrum of lung cancer-associated molecular alterations.