My Brother Is 31 Years Old And Has Enlarged Lymph

My brother is 31 years old and has enlarged lymph nodes and has lost a lot of weight. He went to the doctors and they did bloodwork. He called for results on 11/13 and they told him he had to come in for results and to bring someone with him. His appointment is 11/17. We are terrified that it's cancer. Why would they make him wait 4 days if it's something serious? What else could it be besides cancer?