Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.

Participants who had human epidermal growth factor receptor 2 (HER2) gene amplification or HER2 mutation, advanced non-small cell lung cancer (NSCLC) of any histology and had received prior chemotherapy or prior EGFR-targeted therapy, received dacomitinib 45 mg or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Participants who had not received prior therapy for advanced NSCLC, received 30 mg daily and participants who had received prior systemic therapy for advanced NSCLC, received 45 mg daily as starting dose. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per judgment of the investigator. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg.

Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.

Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.

Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.

Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.

Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.

Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.

Participants who had adenocarcinoma of lung, had not received prior systemic therapy and were either nonsmokers, former light smokers or were known to have an epidermal growth factor receptor (EGFR)-activating mutation, received dacomitinib 45 milligram (mg) or 30 mg tablet orally daily in cycles of 28 days until progression of disease, unacceptable toxicity, or participant withdrawal. Dose escalated to 45 mg in participants after at least 8 weeks of therapy who had started treatment at 30 mg and were tolerating treatment for at least 4 consecutive weeks as per investigator's judgment. Dose modifications for treatment-related toxicity were allowed for up to 2 dose reductions (to 30 mg and then to 15 mg) if the participant started at 45 mg. Dose interruption for treatment-related toxicity was also allowed as per investigator's discretion.