Modulation of Epidermal Growth Factor Receptor Status by Chemotherapy in Patients With Locally Advanced Non–Small-Cell Lung Cancer Is Rare

To determine whether epidermal growth factor receptor (EGFR) expression in non-small-cell lung cancer (NSCLC) is modulated by chemotherapy and to assess the agreement of EGFR status between mediastinal nodes and the primary tumor after chemotherapy. Patients with NSCLC stage IIIa/b pN2/3 confirmed by mediastinoscopy or mediastinostomy were treated with at least three cycles of chemotherapy before undergoing surgery. EGFR expression was evaluated on mediastinal nodes at the time of initial diagnosis and on both the primary tumor and residual metastatic nodes after treatment. EGFR expression determined on 138 of 164 patients who underwent mediastinoscopy or mediastinostomy was 0 (22 patients), 1+ (27 patients), 2+ (28 patients), and 3+ (61 patients). Fifty-four patients of 164 received chemotherapy followed by surgery. Of the 89 of 138 patients with EGFR score of 2+/3+ at the time of diagnosis, 34 patients underwent surgery after induction chemotherapy. None changed to zero EGFR immunoreactivity, with 29 patients (88%) maintaining a score of 2+/3+. Of the 22 of 138 patients with no EGFR expression at the time of diagnosis, six underwent surgical resection after induction chemotherapy. Of these six patients, four changed their EGFR expression from an EGFR score of 0 to 2+/3+. After treatment, the agreement of EGFR status between tumor and nodes in the subgroup of patients with EGFR score 2+/3+ was 89% to 92%. Our data suggest a very good agreement of EGFR status before and after chemotherapy in EGFR-positive NSCLC. Induction chemotherapy can induce EGFR expression in occasional EGFR-negative tumors.