Residual Breast Tissue After Four Types of Mastectomy: A Prospective, Comparative Study

Residual breast tissue (RBT), defined as glandular tissue left behind after mastectomy, raises concerns about oncologic safety. However, data on its prevalence and clinical significance remain limited, with existing studies hampered by small sample sizes and inconsistent methodologies. This study evaluated the prevalence of RBT across four mastectomy types-simple mastectomy (SM), modified radical mastectomy (MRM), skin-sparing mastectomy (SSM), and nipple-sparing mastectomy (NSM)-and identified factors influencing its presence.

This prospective study investigated 350 patients undergoing 403 mastectomies. Tissue samples were collected systematically from eight standardized locations beneath the skin flap for SM, MRM, and SSM, with an additional sample from under the nipple-areolar complex (NAC) for NSM. The study assessed RBT prevalence and associated factors including mastectomy type, breast size, prior surgeries, and surgeon experience.

The study found RBT in 34.2 % of cases, with no significant differences across mastectomy types (p = 0.71). In NSM, 93 % of the cases had RBT under the NAC. Larger breast size was associated with lower RBT prevalence, whereas prior surgeries significantly increased its occurrence (p = 0.03). Surgeon experience (≥ 50 mastectomies annually) was linked to reduced RBT rates in NSM.

Residual breast tissue is a frequent finding regardless of mastectomy type, highlighting the need for standardized evaluation methods and further research into its clinical implications. Tailored surgical approaches and experienced surgeons may help mitigate RBT risk. This study provided critical insights into RBT prevalence and risk factors, offering a foundation for optimizing mastectomy techniques and improving patient outcomes.