The association between tumor epidermal growth factor receptor (EGFR) mutation and multiple primary malignancies in patients with adenocarcinoma of the lungs.

OBJECTIVES: An increased incidence of multiple primary malignancies has been found in recent decades. However, the nature of the association between the epidermal growth factor receptor (EGFR) mutation status and multiple primary malignancies in patients with adenocarcinoma of the lungs is not clearly understood at this time.
METHODS: We retrospectively reviewed the data of our patients with adenocarcinoma of the lungs, and evaluated the association between the tumor EGFR mutation status and multiple primary malignancies.
RESULTS: From December 2008 to November 2011, 655 pulmonary adenocarcinoma patients with tumor EGFR mutation data were available for analysis. Of them, 359 had EGFR mutations (including 336 classic EGFR mutations), 63 had double primary malignancies, and 7 had triple primary malignancies. Patients with classic EGFR mutations had a higher incidence of multiple primary malignancies than those without (P=0.042). Multiple primary malignancies occurred more frequently in patients with exon 19 mutations (including insertions, point mutations, or deletions) or exon 19 deletions than in patients without (P=0.037 and 0.032, respectively). Patients with any EGFR mutations or classic EGFR mutations survived longer than those who did not (P<0.001 and <0.001, respectively). Patients with multiple primary malignancies survived for a longer period than those without (P=0.006).
CONCLUSIONS: Multiple primary malignancies occurred more frequently in patients with classic EGFR mutations, especially those with exon 19 deletions.