Discussion: immediate post-mastectomy breast reconstruction followed by radiotherapy: risk factors for complications

Dr. Cowen and co-authors should be commended for their efforts to describe patterns and correlates of complications after mastectomy with immediate tissue expander/implant reconstruction and adjuvant post-mastectomy radiotherapy. It is important for clinicians to understand the outcomes and predictors of successful breast reconstruction among patients receiving radiotherapy. Post-mastectomy radiation therapy is now considered to be an integral component of cancer treatment for many patients. Radiation therapy is associated with a two-thirds reduction in the relative risk of loco-regional failure and a survival benefit in appropriately selected patients [1]. However, radiation is not without its risks. Several retrospective studies have suggested that radiation increases the risk of post-operative complications in patients with expander/implant reconstructions [2]. Therefore, understanding the risk factors for post-operative complications in the setting of reconstruction and radiation will help to improve the informed consent process and assist clinicians and patients alike with treatment decisionmaking. The investigators have performed a thoughtful multicenter cohort study with a prospective design. The reliability and validity of the study results are dependent on the quality of the measures along with statistical efforts to control for potential biases. Randomized control trials are the gold standard for producing high level evidence. However, it is not always feasible to perform randomized clinical trials, when evaluating surgical treatments that are highly dependent on patient preferences such as breast reconstruction. In these situations, multi-center cohort studies can provide high level evidence. However, the cohort study cannot ensure an equal distribution of known and unknown factors that may impact the treatment outcome. The authors were correct in using regression analyses to control for possible known confounding factors that may not be evenly distributed in the study sample. However, the authors would have produced a more statistically robust study, if they had controlled for certain other patient and clinical factors that are known to be associated with surgical complications with post-mastectomy breast reconstruction. For example, the authors found an interesting association between the surgeon and incidence of capsular contracture in the multivariate analysis. The reasons are unclear, but were suggested to be related to surgical control of hemostasis. It would be helpful to include in the regression model factors known to be associated with the incidence of capsular contracture, such as postoperative infection and hematoma [3, 4]. There could be an interaction between the surgeon and one of these complications that would provide better insight into this association. The type of implant was also not controlled for in the analyses. The incidence of capsular contracture can vary by the type of implant material (silicone vs. saline) and the type of implant shell (textured vs. smooth) [5, 6]. In addition, while the investigators are to be commended for requiring some degree of homogeneity of radiation doses and An invited commentary to this article can be found at doi:10.1007/s10549-010-0791-5.