P2.09-09 EGFR Is Highly Mutated in Lung Adenocarcinoma Patients with History of Breast Cancer

Abstract

EGFR gene mutation has been reported to be frequent in the patients with specific clinical features such as female, adenocarcinoma, and East-Asian ethnicity. The mutation rate in lung adenocarcinoma is approximately 50% in Japan. Currently, the molecular mechanism which cause EGFR mutation has not been clarified. If the EGFR mutation in lung adenocarcinoma correlates with specific type of malignancy in the other organ, it could be a clue to find a mechanism which promote carcinogenesis of lung adenocarcinoma. In the current study, we focused on breast cancer. Patients with lung adenocarcinoma who underwent pulmonary resection in our hospital from January 2011 to December 2018 were analyzed. We retrospectively reviewed clinical information such as past illness, radiological findings, pathological diagnosis, and EGFR mutation status. Correlation was tested by chi-square test and p value of less than 0.05 was regarded as statistically significant. A total of 21 patients of lung adenocarcinoma had history of treatment for breast cancer. All patients were female. Among them, EGFR mutation was detected in 20 patients (95%). One patient who were negative for EGFR mutation had history of not only breast cancer but also cervical cancer of uterus and gastrointestinal stromal tumor, and developed angiosarcoma of the skin. Detected EGFR mutation types in 20 patients were as follows; deletion in exon 19 for 9 patients, L858R for 7 patients G719X for two patients, and L861Q for one patient. One patient showed multiple mutation (G719X and L861). In the same period, among 203 lung adenocarcinoma patients without other organ malignancy, 115 showed EGFR mutation (56.7%). There was significant difference in EGFR mutation rate between breast cancer group and no malignancy group (p=0.00058). Patients of lung adenocarcinoma with history of breast cancer showed extremely high positive rate for EGFR mutation in Japan, suggesting underlying common oncogenic molecular mechanism between lung adenocarcinoma and breast cancer. Elucidation of the mechanism may contribute to the diagnosis and treatment of carcinogenesis of breast cancer and lung cancer.