Our research question is ‘Vitamin D Receptor Polymorphism in breast cancer patients’, the concepts here is, Vitamin D Receptor Polymorphism and breast cancer.
You can use phrase searching, which is one step better than just keyword searching. This is when want words to appear next to each other in an exact phrase. To perform a phrase search, you put the words into quotation marks so as to retrieve the exact match
“attention deficit disorder” will retrieve results with the exact words appearing next to each other
“Vitamin D Receptor Polymorphism” AND “breast cancer”
(You note here we have combine exact phrase searching and Boolean operator “AND” to search for the exact phrases of the 2 identified concepts in our research question)