Are blood pressure and mastectomy related?

No: The two have no relation. Many people who have had mastectomy may also have lymph nodes removed in the armpit. This may impede the flow of fluid from the arm back to the body. These people are often suggested to avoid trauma, finger sticks for blood work and blood pressure cuffs as that can increase the problem and cause lymphedema. That is the only connection.

BP MASTECTOMY: No. But if you have had a radical mastectomy they may tell you not to have BP taken on that side. This was because some got so much swelling that you could not hear BP well on that side. Once swelling stabilizes it is ok to use that arm if the other arm cannot be used for some reason. Say there is no arm on other side.