Join Kristine Kokeny, MD and John Ward, MD as they present their multidisciplinary expertise on a range of cases pertaining to adjuvant systemic therapy for breast cancer.

The purpose of adjuvant systemic therapy is to improve the disease-free survival and overall survival rates after treatment with local therapies (surgery with or without radiation). The incorporation of adjuvant therapy has made a significant positive impact on clinical outcomes in patients with breast cancer.

The benefit from adjuvant systemic therapy differs according to breast cancer subtype. Algorithms have been published estimating rates of recurrence, and a validated computer‑based model (Adjuvant! Online) is available to estimate 10‑year disease‑free and overall survival. These tools aid the clinicians in objectively estimating outcome with local treatment only and in estimating the absolute benefits expected from systemic adjuvant therapy.

Gene‑based assays are used increasingly in making decisions regarding the use of adjuvant chemotherapy in hormone receptor positive, lymph node negative tumors. These assays help quantify risk and make individualized decisions regarding the benefit of adjuvant chemotherapy based on risk of recurrence for early stage breast cancer. The threshold for using adjuvant chemotherapy remains a controversial issue. While the benefit of adjuvant chemotherapy to patients with high risk of recurrence is clear, the additional benefit from adjuvant chemotherapy in addition to endocrine therapy for patients with intermediate‑risk (as assessed by the gene‑based assays) is currently unclear. Prospective randomized clinical trials are addressing the use of Oncotype DX and MammaPrint as predictive and/or prognostic tools in women with early‑stage, lymph node‑negative breast cancer.

Tumor biomarkers (ER/PR and HER-2 receptors) are most useful for predicting response to particular therapies (i.e., endocrine therapy and/or HER2 targeted therapy). Adequate standardization and validation of these biomarker assays used is a concern, and false‑positive determinations are common. The NCCN Panel endorses the recently updated ASCO/CAP recommendations for HER2 testing for quality control and interpretation of results.

Endocrine therapy is mainstay adjuvant treatment for all patients with hormone receptor positive breast cancer regardless of age, lymph node status, and treatment with adjuvant chemotherapy. An ongoing issue in the treatment of hormone receptor positive disease is duration of endocrine therapy.  Selecting the most efficient treatment strategy based on patient characteristics and adverse effects can be challenging. For postmenopausal women the treatment algorithm is complex with several different adjuvant strategies such as: treatment with aromatase inhibitors (AI); versus the sequential strategy, starting with tamoxifen and switching to AI; versus treatment with tamoxifen alone 10 years. The results of a recent large randomized trial (ATLAS) show that for premenopausal women with early hormone positive  breast cancer, 10 years of tamoxifen is better than stopping after 5 years. The NCCN guidelines recommendations for adjuvant endocrine therapy incorporate the findings of the ATLAS trial.