When doing a breast self-exam (BSE), you feel for anything new or different. You will be able to feel a particularly lumpy portion of the breast. Sometimes cysts appear and disappear. Masses that come and go are generally not cancerous. Other than new lumps, look for nipple discharge (either clear or bloody), dimpling of the skin, thickening of the skin, redness of the skin, pain, new lumps, or a fullness feeling in the armpit.
There is a lack of evidence that breast self-exams can reduce your risk of death from breast cancer. The USPSTF does not recommend this self-screening, and the ACS views the exam as optional for women aged 20 and older. ACOG suggests that it is considered in high-risk women.
If you are unsure as to whether you should do a breast self-exam, talk to your doctor.