The NYT reports in an article that attributes the decision to irrational fear.
But there's a link in the sidebar, under "related coverage," to a piece from last October, by the same reporter, Roni Carin Rabin, titled "‘Going Flat’ After Breast Cancer," about women choosing not to go through breast reconstruction after a mastectomy. This article — with many photographs — celebrates the post-mastectomy, unreconstructed look. But all of these women have had both breasts removed.
Putting the 2 articles together, I would guess that at least some of the women opting for a double mastectomy are at least partly thinking about the aesthetics of symmetry. The new article does have this:
Researchers initially thought that women would be more likely to choose a double mastectomy in regions where reconstructive surgery is more commonly done because they wanted symmetrical reconstructed breasts, but many states with high rates of double mastectomies do not have high rates of reconstructive surgery, and vice versa.How about symmetrical unreconstructed breasts? I'm surprised Rabin doesn't consider this possibility, because the article she wrote last year shows women who are critical of the pressure to reconstruct:
For years, medical professionals have embraced the idea that breast restoration is an integral part of cancer treatment.... In promoting the surgery, doctors cite studies that suggest breast reconstruction improves a woman’s quality of life after cancer. But some women say that doctors focus too much on physical appearance, and not enough on the toll prolonged reconstructive procedures take on their bodies and their psyches. Up to one-third of women who undergo reconstruction experience complications. A systematic review of 28 studies found that women who went without reconstruction fared no worse, and sometimes did better, in terms of body image, quality of life and sexual outcomes.