Get comfortable with your breasts and be aware of what their "normal" state is. "Normal" is unique for each woman, but get to know how your breasts generally look and feel. Establish a familiarity with them and their texture, contours, size, etc. You’ll be better able to recognize any changes and then communicate those changes to your physician. In addition, becoming more aware can help you feel empowered as you take an active role in your own health and well-being.  Increasing breast awareness is one of the best things you can do for yourself if you are concerned about breast cancer. By becoming aware of what is normal for you, you'll be better able to assess when something is abnormal.  Note that even things like breast asymmetry, where one breast is a slightly different size or in a slightly different position, are generally completely normal. You generally should only have cause for concern if things change from the way they usually are (for example, one breast grows significantly larger, etc.). If you have a spouse or partner, make him or her part of the process of checking your breasts and becoming more aware of your breast tissue. This is especially important because your partner sees and touches your body from a different angle and may be able to see things that you cannot. Ask your partner to communicate any changes s/he may notice or feel. In the past, a monthly breast self-examination (BSE) was recommended for all women. However, in 2009 the US Preventative Services Task Force recommended against teaching women to do consistent and formal self-examinations after several large research studies concluded that BSE didn't reduce mortality or increase the number of cancers found. Subsequent studies have confirmed that BSE is of no importance in detecting malignant lesions in the breasts.  At present, the American Cancer Society and the US Preventative Services Task Force recommend that BSE should be done at your own discretion. These organizations also emphasize that the real key is to be aware of what...

TL;DR in Vietnamese:
Tăng cường nhận thức về vú. Tự kiểm tra vú còn là vấn đề gây ra nhiều tranh luận. Biết phải chú ý điều gì. Tự kiểm tra vú bằng mắt. Tự kiểm tra vú bằng tay.