A Case of a Pregnant Woman Diagnosed as Having ALK-rearranged Lung Adenocarcinoma

A 28-year-old woman who was 34 weeks pregnant was admitted with complaints of cough and blood-stained sputum. After delivery of the baby at 37 weeks gestation, computed tomography and magnetic resonance imaging revealed a tumor in the right lung and a 15-mm brain metastasis. A diagnosis of lung adenocarcinoma was made, cT4N3M1b (stage IV disease) by pleural fluid cytology. Additional testing for anaplastic lymphoma kinase (ALK) fusion protein showed a strongly positive result, which was then confirmed by fluorescence in situ hybridization. The patient was started on treatment with alectinib, and the tumor and brain metastasis had almost vanished by 2 months after the start of this treatment. In the literature, there are 59 reports of lung cancer diagnosed during pregnancy, including two cases of cancer with expression of ALK fusion protein and five cases showing epidermal growth factor receptor mutation. The type of mutation should be taken into consideration while selecting for the appropriate therapeutic strategy.