**6. Radiotherapy**

Radiotherapy is an essential part of the multidisciplinary approach towards treating breast cancer. Post mastectomy radiotherapy is indicated with large tumour size (>5 cm), a positive margin, >4 positive lymph nodes on axillary dissection or cutaneous involvement. Early stage cancers with 1–3 positive nodes are also considered for treatment however hormone treatment is a reasonable alternative in older patients with stage 1 hormone receptor positive tumours. With the advent of neoadjuvant chemotherapy, radiotherapy is also recommended if the patient remains node positive post operatively [50]. These guidelines are derived from the substantial mortality benefit from postmastectomy radiotherapy and multidisciplinary discussion is recommended in their implementation. As early stage cancers are detected and treated earlier resulting in improved overall survival rates, the choice of reconstruction becomes increasingly important for long term quality of life. Radiotherapy has long been associated with soft tissue injury and inhibition of angiogenesis. It compromises breast pocket viability and wound healing while in the long term, irradiation of an implant based reconstruction can develop complications of capsular contraction and implant rupture [51]. Radiotherapy following implant reconstruction has consistently been associated with higher rates of reoperation and failure within the literature. Zhang et al. reported the reoperation rate as 15.4% compared to 6.7% of the control group while Chetta et al. observed that implants were 11 times more likely to result in reconstructive failure post radiotherapy relative to autologous reconstruction [52, 53]. The Mastectomy Reconstruction Outcomes Consortium (MROC) study, the most comprehensive review of post mastectomy radiation therapy, also found that major complications rates occurred in 33.2% of irradiated implant based reconstructions [54]. With this high incidence of complications, post mastectomy radiation is a relative contra-indication for DTI reconstruction.
