METHODS FOR QUANTIFYING BREAST CANCER-RELATED LYMPHEDEMA IN PATIENTS UNDERGOING A CONTRALATERAL PROPHYLACTIC MASTECTOMY

Patients treated for breast cancer are at risk of developing breast cancer-related lymphedema (BCRL). A significant proportion of patients treated for breast cancer are opting to undergo a contralateral prophylactic mastectomy (CPM). Currently, it remains unclear as to whether the relative volume change (RVC) equation may be used as an alternative to the weight adjusted change (WAC) equation to quantify BCRL in patients who undergo CPM. In order to simplify BCRL screening, our cohort of patients who underwent a CPM (n=310) was matched by BMI to a subset of patients who underwent unilateral breast surgery (n=310). Arm volume measurements were obtained via an optoelectronic perometer preoperatively, postoperatively, and in the follow-up setting every 6-12 months. The correlation of ipsilateral RVC and WAC values for those who underwent bilateral surgery was calculated (r=0.60). Contralateral WAC values for patients in both cohorts were compared, and there was no significant difference between the two distributions in variance (p=0.446). The RVC equation shows potential to be used to quantify ipsilateral postoperative arm volume changes for patients who undergo a CPM. However, a larger trial in which RVC and WAC values are prospectively assessed is needed.

Association Between Genetic Testing for Hereditary Breast Cancer and Contralateral Prophylactic Mastectomy Among Multiethnic Women Diagnosed With Early-Stage Breast Cancer

PURPOSE Increasing usage of multigene panel testing has identified more patients with pathogenic or likely pathogenic (P or LP) variants in low-moderate penetrance genes or variants of uncertain significance (VUS). Our study evaluates the association between genetic test results and contralateral prophylactic mastectomy (CPM) among patients with breast cancer. METHODS We conducted a retrospective cohort study among women diagnosed with unilateral stage 0-III breast cancer between 2013 and 2020 who underwent genetic testing. We examined whether genetic test results were associated with CPM using multivariable logistic regression models. RESULTS Among 707 racially or ethnically diverse women, most had benign or likely benign (B or LB) variants, whereas 12.5% had P or LP and 17.9% had VUS. Racial or ethnic minorities were twice as likely to receive VUS. Patients with P or LP variants had higher CPM rates than VUS or B or LB (64.8% v 25.8% v 25.9%), and highest among women with P or LP variants in high-penetrance genes (74.6%). On multivariable analysis, P or LP compared with B or LB variants were significantly associated with CPM (odds ratio = 4.24; 95% CI, 2.48 to 7.26). CONCLUSION Women with P or LP variants on genetic testing were over four times more likely to undergo CPM than B or LB. Those with VUS had similar CPM rates as B or LB. Our findings suggest appropriate genetic counseling and communication of cancer risk to multiethnic breast cancer survivors.

Contralateral Prophylactic Mastectomy Improves Survival Only Marginally in Patients with Unilateral Triple-Negative Breast Cancer: A Cohort Study Based on SEER Database

Background: The effect of contralateral prophylactic mastectomy (CPM) on the survival rate of triple-negative breast cancer (TNBC) patients is still controversial. The purpose of this study was to confirm whether unilateral TNBC patients benefit from CPM.Methods: 10006 patients with unilateral TNBC in the Surveillance, Epidemiology and End Results (SEER) database were enrolled in this study, propensity score matching (PSM) was applied to balance patient assignments. After PSM,3039 pairs of patients were divided into a CPM group and no-CPM group, respectively. All the patients have undergone total mastectomy or radical mastectomy. Cox proportional hazards regression models were used to evaluate overall survival (OS) and breast cancer-specific survival (BCSS) of the two groups. Subgroup analysis was introduced to exclude the effect of confounding factors. To identify potential variables for prognosis, Kaplan–Meier survival analysis and Cox regression analysis were used and were presented by Kaplan–Meier curve and forest plot separately.Results: With a median follow‐up time of 34.5months (IQR 1–83 months), the estimated 5-year BCSS rates for patients in the CPM group and the no-CPM group were 81.96% and 78.71%, the 5-year OS rates were 80.10% and 75.05%, respectively. CPM improved the BCSS (hazard ratio [HR]= 0.79; 95% confidence interval [CI]=0.69-0.90, p=0.001) and OS (HR= 0.74; 95% CI=0.66-0.84, p<0.001) of unilateral TNBC patients. Univariate subgroup analyses revealed that there was no significant difference in survival time for patients in stage N3 who underwent CPM or not (p>0.05).Conclusions: CPM only limitedly improved BCSS and OS in patients with unilateral TNBC undergoing total mastectomy or radical mastectomy and was not recommended for stage N3 patients.