A method of differentiating among the presence of ductal carcinoma in situ in the breast, benign fibroadenoma of the breast, and non-cancerous breast tissue in a subject is disclosed. The method involves measuring the concentration of at least one protein biomarker selected from a group of forty-nine differentially expressed proteins in the saliva of persons with DCIS, or benign fibroadenoma, or in persons who are cancer-free. The resulting test data is compared to a reference panel. From the comparison the presence in the subject of either ductal carcinoma in situ of the breast, or benign fibroadenoma of the breast is determined.