# Design and Evaluation of Masteromy Bras Using 3D Virtual Prototyping
## 1 Introduction  
Breast cancer is the most common type of cancer in women worldwide, with approximately 99% of breast cancer cases occurring in women and 0.5-1% in men [1]. Mastectomy, a common and effective treatment option for breast cancer, involves the complete surgical removal of breast tissue [2]. Mastectomy has been shown to lead to physical complications in a significant proportion of patients. As a result of the altered body structure, 78% of patients develop upper body curvature of up to 3 deg, often leading to physical complications such as postural imbalances, scoliosis, and restricted shoulder mobility [3]. Unilateral mastectomy can lead to back pain, kyphosis, balance loss, and gait disorders [4, 5, 6]; regular useof mastectomy bras and prostheses is crucial for maintaining balanced posture and body image [7]. The regular use of breast prostheses helps alleviate scoliosis while improving shoulder mobility, thereby preventing spinal disorders [8]. Mastectomy can negatively impact body image, potentially leading to psychosocial issues including reduced self-confidence, social isolation, and decreased sexual interest [9; 10]. Studies conducted after breast cancer treatment have found a significant decrease in sexual desire among women who have undergone mastectomy [11]. In this context, mastectomy bras not only provide physical support but also contribute to psychological recovery by improving women's body image [12]. These bras, designed to hold external prostheses, are vital for correcting posture and ensuring prosthesis stability [13]. Next-generation mastectomy bras should be improved in terms of comfort and aesthetics to positively contribute to the quality of women's life [14]. Rather than being perceived solely as medical products, the diversity of these bras as part of daily life provides both aesthetic and psychological benefits. The global mastectomy bra market is rapidly growing, expected to reach USD 1624.2 million by 2024 and grow at a rate of 9.50% between 2024 and 2031 [15]. This significant market growth highlights the increasing demand for innovative and personalized mastectomy bra designs that not only meet physical and functional needs but also address aesthetic expectations. Existing studies on mastectomy bras indicate that these bras do not fully meet user needs. Factors such as fit problems and deficiencies in prosthesis placement are highlighted as negatively affecting user satisfaction [16]. Several studies in the literature highlight existing problems, analyze women's needs and preferences, and provide functional design suggestions for bra designers [17; 18]. For example, [PERSON] et al. (2014) conducted a study on the support needed by women who underwent mastectomy during exercise and developed suggestions to improve quality of life by focusing on skin sensitivity and asymmetric cup sizes [19]. Additionally, previous studies include findings indicating that imported mastectomy bras are not suitable for local body structures due to differences in body types across nations [20]. In the existing literature, strategies aimed at enhancing bra satisfaction generally focus on two main approaches: the use of sizing tools and software, and the diversification of bra styles and designs [21]. Studies on mastectomy bras have also followed a similar direction, employing methods such as 3D scanning [22] and Magnetic Resonance Imaging (MRI) [16] to conduct sizing studies and evaluate body fit and ergonomics using physical prototypes. The diversity of body shapes following surgery makes the standardization of mastectomy bras extremely challenging. Therefore, personalized bras can better accommodate different body types and needs. However, achieving proper fit and comfort in such designs requires careful consideration of garment pressure, which is influenced by design, fabric structure, and mechanical properties. Garment pressure plays a critical role in clothing comfort, as excessive pressure causes discomfort, while insufficient pressure reduces functionality.