Table 2.

Number of results of each keyword per hit.

Keyword	PubMed	Web of Science	Science Direct
“Afatinib” AND “Non-Small-Cell Lung Cancer”	59	782	788
“Afatinib” AND “Randomized Controlled Trial”	52	27	60
“Afatinib” AND “Squamous Cell Carcinoma of Head and Neck”	10	3	4
Total	121	812	852