MRI-based comparison of skin flap thickness and short-term oncologic outcomes after manual versus robotic nipple-sparing mastectomy.

BACKGROUND

Robotic nipple-sparing mastectomy (R-NSM) has been increasingly adopted because of its potential cosmetic advantages. However, concerns remain regarding thicker skin flaps, residual breast tissue, and oncologic safety compared with manual nipple-sparing mastectomy (M-NSM). This study aimed to compare skin flap thickness and clinical outcomes between M-NSM and R-NSM using postoperative magnetic resonance imaging (MRI).

METHODS

A total of 222 patients who underwent M-NSM (n = 88) or R-NSM (n = 134) with immediate breast reconstruction were retrospectively reviewed. Skin flap thickness was measured on postoperative breast MRI performed approximately 6 months after surgery. Measurements were performed at the subareolar point and peripheral point (mean value of the four measurements located 2 cm from the nipple in the 12-, 3-, 6-, and 9-o'clock directions). Measurements were performed on postoperative T1-weighted breast MRI by two breast surgeons independently. Recurrence and postoperative complications were also evaluated and compared between the two groups.

RESULTS

There was no statistically significant difference in skin flap thickness between the M-NSM and R-NSM groups at either the subareolar point (P = 0.155) or the peripheral point (P = 0.349). Overall recurrence rates were not significantly different between the two groups (P = 1.000), and the postoperative complication rate also showed no statistically significant difference between the two groups (P = 0.853). The median follow-up periods were 659 days in the M-NSM group and 639 days in the R-NSM group. The proportion of patients who received post-mastectomy radiotherapy (PMRT) was significantly higher in the M-NSM group than in the R-NSM group (P < 0.001), which represents a potential confounding factor in the interpretation of both the recurrence outcomes and the measured skin flap thickness.

CONCLUSION

Robotic nipple-sparing mastectomy was not associated with increased postoperative MRI-based skin flap thickness compared with manual nipple-sparing mastectomy, and no apparent differences in short-term recurrence or postoperative complication rate were observed during the follow-up period. However, the short-term follow-up duration, limited number of recurrence events, the significant between-group difference in PMRT use and its variable timing relative to postoperative MRI, and the indirect nature of skin flap thickness as a surrogate marker limit the interpretation of oncologic outcomes. Further studies with longer follow-up are required to clarify long-term oncologic outcomes.