Parsing Progress in Breast Cancer

Treatment and Outcomes of Women With Large Locally Advanced Breast Cancer

Advances in breast cancer research have made breast cancer a treatable disease. However, there is a population of women who present with large, advanced, or sometimes neglected breast cancers who can prove difficult to treat. These women often require multiple modality treatment including chemotherapy, surgery, and radiation. The purpose of our study is to examine the treatment and outcomes on women with large, locally advanced breast cancers (LABCs).

We identified 8 individuals who presented with LABCs requiring extensive treatment. Patients with inflammatory or metastatic cancer at the time of presentation were excluded. These patients' charts were reviewed and analyzed. Patient demographics, hormone receptor status, stage, types of treatment, presence of metastasis, survival, and presence of barriers for seeking treatment sooner were identified.

The median age at presentation was 65 years old. The patients were equally African American and Caucasian. All patients presented with T4 or stage 3 tumors involving the skin and/or pectoralis muscle. Half of the patients were found to have triple-negative (estrogen receptor, progesterone receptor, Her-2/neu negative) tumors. 87% of the patients received chemotherapy; 1 refused. All 8 patients, either neoadjuvantly or adjuvantly, underwent a modified radical or radical mastectomy. Skin graft or flap coverage was necessary in half of the patients. Postmastectomy radiation was received in 87% of the patients; 1 patient refused the treatment. Half of the patients developed metastatic disease. Thirty-seven percent of the patients have since died with a median survival of 44 months. Reasons for delay in seeking care were monetary or social barriers. Many of the patients finally sought care via the emergency room due to symptoms they could no longer ignore.

Women who present with LABC require complex multidisciplinary treatment consisting of chemotherapy, surgery, and radiation treatments. Many of these patients faced economic and social challenges to accessing care. Better access to care and more prompt connection to breast surgeons are required to assist this patient population.

The prognostic role of RANK SNP rs34945627 in breast cancer patients with bone metastases

Receptor activator of NF-kB (RANK) pathway regulates bone remodeling and is involved in breast cancer (BC) progression. Genetic polymorphisms affecting RANK-ligand (RANKL) and osteoprotegerin (OPG) have been previously associated with BC risk and bone metastasis (BM)-free survival, respectively. In this study we conducted a retrospective analysis of the association of five missense RANK SNPs with clinical characteristics and outcomes in BC patients with BM. SNP rs34945627 had an allelic frequency of 12.5% in BC patients, compared to 1.2% in the control group (P = 0.005). SNP rs34945627 was not associated with any clinicopathological characteristics, but patients presenting SNP rs34945627 had decreased disease-free survival (DFS) (log-rank P = 0.039, adjusted HR 2.29, 95% CI 1.04–5.08, P = 0.041), and overall survival (OS) (log-rank P = 0.019, adjusted HR 4.32, 95% CI 1.55–12.04, P = 0.005). No differences were observed regarding bone disease-free survival (log-rank P = 0.190, adjusted HR 1.68, 95% CI 0.78–3.66, P = 0.187), time to first skeletal-related event (log-rank P = 0.753, adjusted HR 1.28, 95% CI 1.42–3.84; P = 0.665), or time to bone progression (log-rank P = 0.618, adjusted HR 0.511, 95% CI 0.17–1.51; P = 0.233). Our analysis shows that RANK SNP rs34945627 has a high allelic frequency in patients with BC and BM, and is associated with decreased DFS and OS.

The DNA cytosine deaminase APOBEC3B promotes tamoxifen resistance in ER-positive breast cancer

Breast tumors often display extreme genetic heterogeneity characterized by hundreds of gross chromosomal aberrations and tens of thousands of somatic mutations. Tumor evolution is thought to be ongoing and driven by multiple mutagenic processes. A major outstanding question is whether primary tumors have preexisting mutations for therapy resistance or whether additional DNA damage and mutagenesis are necessary. Drug resistance is a key measure of tumor evolvability. If a resistance mutation preexists at the time of primary tumor presentation, then the intended therapy is likely to fail. However, if resistance does not preexist, then ongoing mutational processes still have the potential to undermine therapeutic efficacy. The antiviral enzyme APOBEC3B (apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3B) preferentially deaminates DNA C-to-U, which results in signature C-to-T and C-to-G mutations commonly observed in breast tumors. We use clinical data and xenograft experiments to ask whether APOBEC3B contributes to ongoing breast tumor evolution and resistance to the selective estrogen receptor modulator, tamoxifen. First, APOBEC3B levels in primary estrogen receptor-positive (ER+) breast tumors inversely correlate with the clinical benefit of tamoxifen in the treatment of metastatic ER+ disease. Second, APOBEC3B depletion in an ER+ breast cancer cell line results in prolonged tamoxifen responses in murine xenograft experiments. Third, APOBEC3B overexpression accelerates the development of tamoxifen resistance in murine xenograft experiments by a mechanism that requires the enzyme's catalytic activity. These studies combine to indicate that APOBEC3B promotes drug resistance in breast cancer and that inhibiting APOBEC3B-dependent tumor evolvability may be an effective strategy to improve efficacies of targeted cancer therapies.