KRAS and lung cancer: Approximately 10% of individuals over the age of 65 years show clonal expansion of cancer-associated mutations in their blood.[23] A Chinese lung cancer gene mutation study showed that ALK, KRAS, and BRAF gene abnormalities were mainly found in patients aged <60 years, while other genes were dominant in elderly patients.[24] Therefore, proto-oncogene is not the only important reference factor for elderly cancer patients, and the corresponding targeted therapies such as lenvatinib mentioned above, have limited efficacy.