Even the most vocal of critics will admit that there are few long term studies on breast implants, although many are underway now. Others will say this a poor comparison because the cancer-smoking link was also hidden from the public by greedy corporations. This may or may not be true, but another reason is scientific, not commercial. Long term, double blind studies are expensive and difficult to conduct with human subjects. Conversely, results from animal studies are much easier to obtain but often difficult to apply to human situations.
Artificial breasts do fall into the elective category.
So now let's say you are very depressed about the size of your breasts. They make you unhappy. They make your lover or husband unhappy. You feel inferior or somehow incomplete because of the size of your breasts. This choice breaks into two sub-options.