Anaplastic lymphoma kinase-positive lung adenocarcinoma patient with development of sick sinus syndrome while on targeted treatment with crizotinib.

The anaplastic lymphoma kinase (ALK) positive non-small cell lung cancer (NSCLC) patients are younger and have never smoked, while pathologically are predominately adenocarcinomas. Crizotinib as an ALK inhibitor has been used in treating ALK positive NSCLC patients for several years and some adverse effects should be paid attention to. We now describe a case of ALK positive NSCLC patient with development of sick sinus syndrome (SSS) while on targeted treatment with crizotinib. A 46-year-old non-smoking woman with right hilar mass and underwent transesophageal endoscopic ultrasonography lymph node biopsy showed low differentiation adenocarcinoma, immunohistochemistry (IHC) of tumor samples revealed the ALK overexpression. The severe sinus bradycardia and RR interval prolongation were detected 3 months after crizotinib treatment, she underwent pacemaker implantation. Although the severe sinus bradycardia and RR interval prolongation were unusual adverse effects, physicians should be aware of these side effects when using crizotinib.