A prospective cohort study to analyze the interaction of tumor-to-breast volume in breast conservation therapy versus mastectomy with reconstruction

Purpose: We explored the impact of the relative volume of a tumor versus the entire breast on outcomes in patients undergoing breast conservation therapy (BCT) versus mastectomy and reconstruction (M + R). We hypothesized that there would be a threshold tumor:breast ratio (TBR) below which patient-reported outcomes (PRO) would favor BCT and above which would favor M + R. Methods: We conducted a prospective cohort study of patients with ductal carcinoma in situ (DCIS) or invasive breast cancers undergoing BCT or M + R. A prerequisite for inclusion, analysis of tumor and breast volumes was conducted from three-dimensional magnetic resonance imaging reconstructions to calculate the TBR. Three-dimensional photography was utilized to calculate pre- and postoperative volumes and assess symmetry. Oncologic, surgical, and patient-reported outcome data were obtained from relevant BREAST-Q modules administered pre- and postoperatively. Results: The BCT cohort had significantly smaller tumor volumes (p = 0.001) and lower TBRs (p = 0.001) than patients undergoing M + R overall. The M + R group, however, comprised a broader range of TBRs, characterized at lower values by patients opting for contralateral prophylactic mastectomy. Postoperative satisfaction with breasts, psychosocial, and sexual well-being scores were significantly higher in the BCT cohort, while physical well-being significantly favored the M + R cohort 480.2 ± 286.3 and 453.1 ± 392.7 days later, respectively. Conclusions: Relative to BCT, M + R was used to manage a broad range of TBRs. The relative importance of oncologic and surgical risk reduction, symmetry, and number of procedures can vary considerably and may limit the utility of TBR as a guide for deciding between BCT and M + R. Clinical Trial StatementThis study was registered with clinicaltrials.gov as “A Prospective Trial to Assess Tumor:Breast Ratio and Patient Satisfaction Following Lumpectomy Versus Mastectomy With Reconstruction”, Identifier: NCT02216136.