New research was presented at SABCS 2018, the annual San Antonio Breast Cancer Symposium, from December 4-8. The features below highlight some of the studies that emerged from the conference.
QOL Outcomes after Local Therapy
Data indicate a dramatic increase in recent years in the rates of young women with breast cancer undergoing mastectomy, primarily bilateral mastectomy. The impact of these procedures on the long-term quality of life (QOL) of this patient population is largely unknown. Women diagnosed with breast cancer at age 40 or younger were administered the BREAST-Q, a validated patient-reported outcomes measure, for a study. Mean BREAST-Q scores in the domains of breast satisfaction, physical, psychosocial, and sexual were compared by surgery types. Mean BREAST-Q scores for breast satisfaction, psychosocial, and sexual well-being were lower for patients who had unilateral or bilateral mastectomy, when compared with breast-conserving surgery. Physical function was similar among groups. In multivariate analysis, lower BREAST-Q psychosocial scores were associated with radiation and mastectomy. Lower sexual well-being scores were also associated with mastectomy. Lower satisfaction with breast scores following radiation were of a clinically significant magnitude. Lower scores for physical well-being were seen for patients with lymphedema and higher for those who had undergone surgery more than 5 years prior. Lower scores across all domains were associated with reported financial distress.
Exercise Training During Adjuvant Breast Cancer Treatment
Although previous studies indicate that breast cancer survival rates are increasing, cardiovascular disease has emerged as a competing cause of death among breast cancer survivors, with treatment-induced cardiotoxicity remaining a major concern. However, few studies have assessed the effect of aerobic exercise on cardiovascular function during adjuvant breast cancer treatment. For a study, women aged 18-75 with stage I-II breast cancer were randomized after surgery to a control group or an intervention group. The latter group participated in a 12-month exercise program that started 2-3 weeks after surgery and included a detailed training program personalized by baseline maximal oxygen uptake (VO2max), training sessions in groups of 10-12 women for 60 minutes twice a week, and a request to perform at least 240 minutes of exercise at home per week. The intervention group had a 2.7% decrease in VO2max of 2.7% after 6 months, but improved by 2.3 % at 12 months compared with before surgery. Breast cancer patients in the control group had a 10% reduction in VO2max at 6 months and a 3.8% decrease in at 12 months. Among patients who received chemotherapy, those in the control group had a 16.2% decrease in VO2max at 6 months, compared with only a 7.5% decrease for those in the intervention group.
Comparing Approaches for Positive SNBs
Evidence indicates that sentinel node biopsy (SNB) is standard in assessing axillary lymph node status in patients with clinically node-negative breast cancer. Analysis of 5-year data from prior research suggests that axillary radiotherapy is a reasonable alternative for axillary lymph node dissection, with less side effects, when locoregional treatment is advised after a tumor-positive axillary SNB. Researchers conducted further analyses on this same study population to assess outcomes at 10 years. Patients who underwent axillary lymph node dissection had 5- and 10-year axillary recurrent rates of 0.41% and 0.93%, respectively. These rates were 1.04% and 1.82%, respectively, for those who underwent axillary radiotherapy. No significant differences were observed between the groups in overall or distant metastasis-free survival. Cumulative incidence estimates of 10-year locoregional recurrence were 3.59% for axillary lymph node dissection and 4.07% for axillary radiotherapy. The study authors concluded that axillary radiotherapy is a safe treatment option for breast cancer patients with a tumor-positive SNB.
Post-Pathological Complete Response Outcomes
Although the prognostic significance of pathological complete response (pCR) after neoadjuvant chemotherapy for patients with breast cancer is relatively well established, less is known regarding the impact of adjuvant therapy in modulating the relationship between pCR and long-term outcomes. Researchers conducted a systematic review of published neoadjuvant chemotherapy studies to comprehensively evaluate the association between pCR with subsequent breast cancer recurrence and mortality, stratified by breast cancer subtypes and adjuvant chemotherapy usage. Among nearly 28,000 patients from 52 studies, attainment of pCR was associated with significantly reduced disease recurrence overall as well as in triple-negative and HER2+ breast cancers, while trending toward significance for HR+ breast cancer. Overall and among all three major disease subtypes, pCR after neoadjuvant chemotherapy was associated with reduced mortality. The association of pCR with reduced recurrence was similar among studies in which patients did and did not receive subsequent adjuvant chemotherapy.
Cutting Cardiotoxicity Risk in HER+ Breast Cancer
Data indicated that adjuvant trastuzumab is the standard of care for patients with early-stage HER2+ Breast cancer, despite a potential for cardiotoxicity that requires monitoring and often leads to dose interruption, discontinuation, or both. Results of several small studies suggest that treatment-induced cardiotoxicity might be prevented by prophylaxis with an ACE inhibitor or beta blocker. For a study, patients with early HER2+ breast cancer being treated with trastuzumab were stratified by use of anthracycline-containing chemotherapy and randomized to a beta-blocker, ACE inhibitor, or placebo for 52 weeks starting on day 1 of trastuzumab treatment. Patients who received trastuzumab without anthracycline-containing chemotherapy had similar rates of cardiotoxicity in all three groups. However, the incidence decreased by about half among those who received anthracycline-containing adjuvant or neoadjuvant therapy and either the beta-block or ACE inhibitor, when compared with those who received placebo. Interruption of trastuzumab therapy occurred significantly more often in the placebo group, with anthracycline use accounting for most of the difference, as trastuzumab interruption occurred in 40.3% of the placebo group, 19.7% of the beta-blocker group and 23.0% of the ACE inhibitor group. Adverse events associated with the beta-blocker and ACE inhibitor were consistent with their known safety profiles.