BMI, Not Implant Size Mismatch, May Best Predict MSFN Risk

Lisa Cassileth, MD, FACS, chief executive officer and founder of The Practice Healthcare, discussed findings from her retrospective study, published in Aesthetic Surgery Journal Open Forum, in which multivariate logistic regression identified body mass index (BMI), rather than the numerical difference between implant and mastectomy specimen size, as the key predictor of mastectomy skin flap necrosis (MSFN). She explained how reconstructive teams should weigh BMI, tissue tension, and mastectomy flap quality when planning direct-to-implant (DTI) cases and described how intraoperative imaging can support that decision.

Transcript:

CancerNetwork: The multivariate analysis identified BMI, rather than the implant-to-specimen size discrepancy, as the key predictor of MSFN. How should reconstructive teams weigh patient BMI vs tissue tension when planning DTI cases?

Cassileth: Doctors [hearing] this, and patients too, will already know it’s not as simple as looking at BMI or making a straight decision about whether to go up or down [in size]. It’s about looking at that patient on that day. There’s a huge variation in the quality of the mastectomy flap. The mastectomy flap is what’s left behind, the tissue and subcutaneous fat, after I’ve removed the breast. That plane isn’t easy [to find]. We’re asking general surgeons and breast surgeons, the mastectomy surgeons, to cut between the subcutaneous fat and the breast. If you think about it, in a fatty, larger breast, that plane is harder to find because you’re trying to find a plane between fat and fat. Not only that, I’m often finding that plane starting from the inframammary crease, at the bottom of the breast, working up. By the time I get to the top, it’s fat on fat. It’s technically difficult for the general surgeon, breast surgeon, or breast oncologist, whoever performs the mastectomy.

The reconstructive team comes in and asks, can I upsize? It depends on how it looks. It’s not a knee-jerk answer that upsizing is wrong; that’s what we know from the study. I also wouldn’t say you have to upsize [because] it’s safer. I’d say you have to trust your gut in terms of looking at the quality of the skin and the quality of the mastectomy flap. There are now devices, like SPY PHI , where I can give the patient an indocyanine green [ICG] dye and look at the blood flow. Those measurements are much stronger predictors than BMI or absolute size. Ultimately, it comes down to the surgeon choosing an implant for that patient on that day, and that’s what we need to trust: the surgeon’s judgment. If a surgeon tells their patient, “When I work with this general surgeon, I’m going to use a smaller size, take more skin off, and place a tissue expander,” that’s because they have experience with that surgeon. It’s not that they’re not capable of doing it; they’re telling the patient what’s safe for that patient and for that surgeon’s patients.

Reference

Cassileth LB, Killeen KL, York A, Rosen D. Does breast implant size larger than mastectomy specimen size increase the risk of flap necrosis? Aesthet Surg J Open Forum. 2026;8:ojag063. doi:10.1093/asjof/ojag063