I have some pain on the lower left side of my left breast for the past 4 years. 3 years ago i took a mammogram and there were no findings.is it tumor?

No: For the most part breast pain is not a hallmark of breast cancer. The inability to note a lump in the area of pain with a negative mammogram further reinforces the pain process as benign . In addition the presence of t he pain symptoms for 4 yrs without progression of the degree of pain further suggests stability of the process which for the most part is related to fibrocystic disease.