If A Person Has A Lump And Your Doctor Sends

If a person has a lump and your doctor sends you for a mammogram, can the doctor see from mammogram results whether the lump is cancerous or would a person have to have a biopsy? I'm concerned because my doctor never saw my results because he went away for his own family emergency. I never heard from any other doctor who was taking his test results. My mother and my sister both have had breast cancer.