Do fat cells die after a year of the fat transfer to the breast?

I would suggest getting an ultrasound and possible mammogram to check each lump. You may have some fat necrosis from the transfer, but it is best to check to make sure it is not something else. Usually most of the fat necrosis occurs early in the first 6 months.

In order for grafted tissue to remain viable or alive it needs to go through a revascularization process that typically happens within the first couple of weeks after surgery. After that point any fat that does not have a blood supply is dead and will continue along the course of necrotic tissue and the fat cells that are alive will continue to strengthen their blood supply and become permanently incorporated in the body in their new location. Small areas of necrotic fat will be absorbed without clinical significance and will not leave lumps. large collections of necrotic fat will create enough inflammation and scar tissue to become palpable lumps. The absence of having lumps after fat transfer procedure is technically dependent. if grafted fat is properly stratified through the host tissue in various layers without leaving a significant amount of grafted fat in a single location the patient will not develop palpable nodules or noticeable fat necrosis.
In order for fat to survive it needs to be surrounded by live vascular tissue and for this reason surgeons need to avoid overgrafting in any one specific area.
If probable fat necrosis nodules are present patients can either have them surgically excised or simply live with them. patients who are of age of having mammograms should get mammograms and expect mammogram readings to be changed because of the fat transfer procedure.
Fat necrosis evolves over time depending on how much fat the body is trying to absorb.
I suggest you follow up with your provider and have him or her assess your outcome and discuss your current situation.
Best,
Mats Hagstrom MD