STK11 and breast cancer: In addition, germ-line mutations of LKB1 gene are also found in some extraintestinal cancers, such as lung cancer [5,6], breast cancer [7,8], cervical adenocarcinoma [5], pancreatic and biliary carcinoma [5,9,10], testicular cancer , malignant melanoma [11,12], head and neck squamous cell carcinoma [13] and hepatocellular carcinoma [14].