Non-Response of Epstein-Barr Virus-Associated Breast Cancer after Primary Chemotherapy: Report of Two Cases.

Based on epidemiological evidence and molecular findings, a possible association of Epstein-Barr virus (EBV) with the carcinogenesis of breast cancer has been described. However, the frequency of EBV in breast cancer and the role of EBV regarding tumor progression or therapeutic results is largely unexplored. Here, we report on two cases of advanced, lymph node-positive invasive breast cancer of no special type (NST), histologically showing no clinical or histological evidence of tumor regression as an equivalent of a lack of response to primary systemic therapy. Both tumors were considered to be EBV-associated due to their positivity in EBV-encoded RNA (EBER) in situ hybridization (ISH) and their immunoreactivity against EBV Epstein-Barr nuclear antigen 1 (EBNA1). We hypothesize that the unusual non-response to chemotherapy in these cases of breast cancer classified as triple-negative and HER2-positive may be linked to the EBV co-infection of tumor cells. Therefore, EBV tumor testing should be considered in patients with breast cancer presenting with resistance to chemotherapy. This hypothesis may provide a new aspect in the context of EBV-associated mechanisms of tumor progression.

Palliative Radiotherapy for Symptomatic Locally Advanced Breast Cancer.

Objective: Women with locally advanced breast cancer (LABC) or inoperable local recurrence often suffer from a significantly reduced quality of life (QOL) due to local tumor-associated pain, bleeding, exulceration, or malodorous discharge. We aimed to further investigate the benefit of radiotherapy (RT) for symptom relief while weighing the side-effects. Materials and methods: Patients who received symptom-oriented RT for palliative therapy of their LABC or local recurrence in the Department of Radiation Oncology at Heidelberg University Hospital between 2012 and 2021 were recorded. Clinical, pathological, and therapeutic data were collected and the oncological and symptomatic responses as well as therapy-associated toxicities were analyzed. Results: We retrospectively identified 26 consecutive women who received palliative RT with a median total dose of 39 Gy or single dose of 3 Gy in 13 fractions due to (impending) exulceration, pain, local hemorrhage, and/or vascular or plexus compression. With a median follow-up of 6.5 months after initiation of RT, overall survival at 6 and 12 months was 60.0% and 31.7%, and local control was 75.0% and 47.6%, respectively. Radiation had to be discontinued in 4 patients due to oncological clinical deterioration or death. When completed as initially planned, symptom improvement was achieved in 95% and WHO level reduction of analgesics in 28.6% of patients. In 36% (16%) of patients, local RT had already been indicated >3 months (>6 months) before the actual start of RT, but was delayed or not initiated among others in favor of drug alternatives or systemic therapies. RT-associated toxicities included only low-grade side-effects (CTCAE I°-II°) with predominantly skin erythema and fatigue even in the context of re-RT. Conclusion: Palliative RT in symptomatic LABC or locoregional recurrence is an effective treatment option for controlling local symptoms with only mild toxicity. It may thus improve QOL and should be considered early in palliative patient care management.

Age-Dependent Hematologic Toxicity Profiles and Prognostic Serologic Markers in Postoperative Radiochemotherapy Treatment for Uterine Cervical Cancer.

Introduction: In the adjuvant setting for cervical cancer, classical risk factors for postoperative radiochemotherapy have been established. However, data on laboratory changes during therapy and the prognostic value of serological markers are limited and further knowledge is needed to optimize the toxic trimodal regimen. Methods: We retrospectively identified 69 women who underwent weekly postoperative radiochemotherapy with 40 mg/m2 of cisplatin for cervical cancer between 2010 and 2021 at a single center. Laboratory parameters were recorded before, at each cycle and after radiochemotherapy. Kaplan-Meier and log-rank analyses were used to calculate and compare survival, groups were compared using the Mann-Whitney U, χ2, and variance tests. Results: With a median follow-up of 17.7 months, the 1- and 5-year local control rates were 94.0% and 73.7%, respectively, with significantly better rates for more chemotherapy cycles and negative resection margins. Only 68.1% of patients completed all cycles. The most common reasons for early discontinuation were persistent asymptomatic leukopenia in women aged ≤ 50 years, and limiting infections in women aged > 50 years. Leukopenia was more likely to occur after the third cycle. Significantly worse survival was observed for post-radiochemotherapy elevated C-reactive-protein and lactate dehydrogenase levels, low pre-radiochemotherapy nutritional index, and raised C-reactive-protein-levels; the latter were also predictable for local control. The Glasgow prognostic score did not reliably predict survival. Conclusion: Incomplete application of simultaneous chemotherapy leads to inferior local control, and age-dependent limiting factors should be identified at an early stage. In addition to classical risk factors, serological markers (C-reactive-protein, lactate dehydrogenase, nutritional index) show prognostic significance.

Cytokine release syndrome-like serum responses after COVID-19 vaccination are frequent and clinically inapparent under cancer immunotherapy.

Patients with cancer frequently receive immune-checkpoint inhibitors (ICIs), which may modulate immune responses to COVID-19 vaccines. Recently, cytokine release syndrome (CRS) was observed in a patient with cancer who received BTN162b2 vaccination under ICI treatment. Here, we analyzed adverse events and serum cytokines in patients with 23 different tumors undergoing (n = 64) or not undergoing (n = 26) COVID-19 vaccination under ICI therapy in a prospectively planned German single-center cohort study (n = 220). We did not observe clinically relevant CRS (≥grade 2) after vaccination (95% CI 0-5.6%; Common Terminology of Adverse Events v.5.0) in this small cohort. Within 4 weeks after vaccination, serious adverse events occurred in eight patients (12.5% 95% CI 5.6-23%): six patients were hospitalized due to events common under cancer therapy including immune related adverse events and two patients died due to conditions present before vaccination. Despite absence of CRS symptoms, a set of pairwise-correlated CRS-associated cytokines, including CXCL8 and interleukin-6 was >1.5-fold upregulated in 40% (95% CI 23.9-57.9%) of patients after vaccination. Hence, elevated cytokine levels are common and not sufficient to establish CRS diagnosis.

Circulating miR-200 family as predictive markers during systemic therapy of metastatic breast cancer.

PURPOSE: Circulating miRNAs can provide valid prognostic and predictive information for breast cancer diagnosis and subsequent management. They may comprise quintessential biomarkers that can be obtained minimally invasively from liquid biopsy in metastatic breast cancer patients. Therefore, they would be clinically crucial for monitoring therapy response, with the goal of detecting early relapse. This study investigated miRNA expression in patients with early and/or late relapse, and the predictive value for assessing overall (OS) and progression-free survival (PFS). METHODS: Forty-seven patients with metastatic breast cancer from the University Women's Hospital Heidelberg were enrolled in this study. Expression of miR-200a, miR-200b, miR-200c, miR-141, and miR-429 was analyzed by RT-qPCR before a new line of systemic therapy and after the first cycle of a respective therapy. Tumor response was assessed every 3 months using the RECIST criteria. Statistical analysis focused on the relation of miR-200s expression and early vs. late cancer relapse in relation to systemic treatment. The association of miRNAs with PFS and OS was investigated. RESULTS: Before starting a new line of systemic therapy, miR-429 (p = 0.024) expression was significantly higher in patients with early relapse (PFS ≤ 4 months) than in patients with late relapse (PFS > 4 months). After one cycle of systemic therapy, miR-200a (p = 0.039), miR-200b (p = 0.003), miR-141 (p = 0.017), and miR-429 (p = 0.010) expression was higher in early than in late progressive cancer. In addition, 4 out of 5 miR-200 family members (miR-200a, miR-200b, miR-141, and miR-429) predicted PFS (p = 0.048, p = 0.008, p = 0.026, and p = 0.016, respectively). Patients with heightened miRNA levels showed a significant reduction in OS and PFS. CONCLUSION: Circulating miR-200s were differentially expressed among patients with late and/or early relapse. 4 of 5 members of the miR-200 family predicted significantly early relapse after systemic treatment. Our results encourage the use of circulating miR-200s as valuable prognostic biomarkers during metastatic breast cancer therapy.

CATCH: A Prospective Precision Oncology Trial in Metastatic Breast Cancer.

PURPOSE: CATCH (Comprehensive Assessment of clinical feaTures and biomarkers to identify patients with advanced or metastatic breast Cancer for marker driven trials in Humans) is a prospective precision oncology program that uses genomics and transcriptomics to guide therapeutic decisions in the clinical management of metastatic breast cancer. Herein, we report our single-center experience and results on the basis of the first 200 enrolled patients of an ongoing trial. METHODS: From June 2017 to March 2019, 200 patients who had either primary metastatic or progressive disease, with any number of previous treatment lines and at least one metastatic site accessible to biopsy, were enrolled. DNA and RNA from tumor tissue and corresponding blood-derived nontumor DNA were profiled using whole-genome and transcriptome sequencing. Identified actionable alterations were brought into clinical context in a multidisciplinary molecular tumor board (MTB) with the aim of prioritizing personalized treatment recommendations. RESULTS: Among the first 200 enrolled patients, 128 (64%) were discussed in the MTB, of which 64 (50%) were subsequently treated according to MTB recommendation. Of 53 evaluable patients, 21 (40%) achieved either stable disease (n = 13, 25%) or partial response (n = 8, 15%). Furthermore, 16 (30%) of those patients showed improvement in progression-free survival of at least 30% while on MTB-recommended treatment compared with the progression-free survival of the previous treatment line. CONCLUSION: The initial phase of this study demonstrates that precision oncology on the basis of whole-genome and RNA sequencing is feasible when applied in the clinical management of patients with metastatic breast cancer and provides clinical benefit to a substantial proportion of patients.

Frequent Molecular Subtype Switching and Gene Expression Alterations in Lung and Pleural Metastasis From Luminal A-Type Breast Cancer.

PURPOSE: Conversion of tumor subtype frequently occurs in the course of metastatic breast cancer but is a poorly understood phenomenon. This study aims to compare molecular subtypes with subsequent lung or pleural metastasis. PATIENTS AND METHODS: In a cohort of 57 patients with breast cancer and lung or pleural metastasis (BCLPM), we investigated paired primary and metastatic tissues for differential gene expression of 269 breast cancer genes. The PAM50 classifier was applied to identify intrinsic subtypes, and differential gene expression and cluster analysis were used to further characterize subtypes and tumors with subtype conversion. RESULTS: In primary breast cancer, the most frequent molecular subtype was luminal A (lumA; 49.1%); it was luminal B (lumB) in BCLPM (38.6%). Subtype conversion occurred predominantly in lumA breast cancers compared with other molecular subtypes (57.1% v 27.6%). In lumA cancers, 62 genes were identified with differential expression in metastatic versus primary disease, compared with only 10 differentially expressed genes in lumB, human epidermal growth factor receptor 2 (HER2)-enriched, and basal subtypes combined. Gene expression changes in lumA cancers affected not only the repression of the estrogen receptor pathway and cell cycle-related genes but also the WNT pathway, proteinases (MME, MMP11), and motility-associated cytoskeletal proteins (CK5, CK14, CK17). Subtype-switched lumA cancers were further characterized by cell proliferation and cell cycle checkpoint gene upregulation and dysregulation of the p53 pathway. This involved 83 notable gene expression changes. CONCLUSION: Our results indicate that gene expression changes and subsequent subtype conversion occur on a large scale in metastatic luminal A-type breast cancer compared with other molecular subtypes. This underlines the significance of molecular changes in metastatic disease, especially in tumors of initially low aggressive potential.

Estrogen, progesterone, and human epidermal growth factor receptor 2 discordance between primary and metastatic breast cancer.

BACKGROUND: The estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) statuses are frequently discordant between the primary tumor and metastatic lesions in metastatic breast cancer. This can have important therapeutic implications. PATIENTS AND METHODS: In all, 541 patients with available receptor statuses from both primary tumor and metastatic lesion treated at Heidelberg and Tuebingen University Hospitals between 1982 and 2018 were included. RESULTS: Statistically significant discordance rates of 14% and 32% were found for ER and PR. HER2 status was statistically insignificantly discordant in 15% of patients. Gain in HER2 positivity was associated with an improved overall survival, whereas loss of HR positivity was associated with worse overall survival. Antiendocrine treatment differed in 20% of cases before and after biopsy and HER2-directed treatment in 14% of cases. CONCLUSIONS: Receptor statuses are discordant between primary tumor and metastasis in a considerable fraction of patients with metastatic breast cancer. Next to a highly presumed predictive value with respect to efficacy of endocrine and HER2-targeted therapy, discordance seems to provide prognostically relevant information. Where feasible, metastatic lesions should be biopsied in accordance with current guidelines.

HER2-targeted therapy influences CTC status in metastatic breast cancer.

PURPOSE: As an independent, negative-prognostic biomarker for progression-free survival (PFS) and overall survival (OS), circulating tumor cells (CTCs) constitute a promising component for developing a liquid biopsy for patients with metastatic breast cancer (MBC). The effects of HER2-targeted therapy such as trastuzumab, pertuzumab, T-DM1, and lapatinib on CTC status and longitudinal enumeration were assessed in this trial. METHODS: CTC status of 264 patients with MBC was analyzed prior to and after 4 weeks of a new line of palliative systemic therapy. CTCs were assessed using CellSearch®. Three groups were compared: patients with HER2-positive MBC receiving ongoing HER2-targeted therapy (n = 28), patients with de novo HER2-positive MBC and no HER2-targeted therapy in the last 12 months prior to enrollment and start of HER2-targeted therapy (n = 15), and patients with HER2-nonamplified disease and no HER2-targeted therapy (n = 212). RESULTS: Positive CTC status (≥ 5 CTC/7.5 ml blood) at enrollment was observed in the 3 groups for 17.9, 46.7, and 46.2% (p = 0.02) of patients, respectively. At least one CTC/7.5 ml was seen in 28.6, 53.3, and 67.0% (p < 0.001) of these patients. Furthermore, 3.6, 40.0, and 3.3% (p < 0.001) of the patients had at least one HER2-positive CTC. After 4 weeks of therapy 7.1, 0.0, and 31.1% (p = 0.001) of patients had still a positive CTC status (≥ 5 CTC/7.5 ml blood). At least one CTC/7.5 ml was still observed in 25.0, 20.0, and 50.5% (p = 0.004) of the patients. Furthermore, 7.1, 0.0, and 1.9% (p = 0.187) had at least one HER2-positive CTC. After 3 months of therapy, 35.7, 20.0, and 28.3% (p = 0.536) showed disease progression. CONCLUSIONS: HER2-targeted therapy seems to reduce the overall CTC count in patients with MBC. This should be taken into account when CTC status is used as an indicator for aggressive or indolent metastatic tumor disease.

Cut-Off Analysis of CTC Change under Systemic Therapy for Defining Early Therapy Response in Metastatic Breast Cancer.

Detection of circulating tumor cells (CTC) can distinguish between aggressive and indolent metastatic disease in breast cancer patients and is thus considered an independent, negative prognostic factor. A clear decline in CTCs is observed in patients who respond to systemic therapy. Nevertheless, CTCs can decrease in patients experiencing disease progression during systemic therapy, too. This study aims to determine the differences between CTC decline in patients responding to therapy and those in whom disease is progressing. Therefore, CTC values were compared at the start and after one cycle of a new line of systemic therapy. In all, 108 initially CTC-positive patients (with ≥5 intact CTCs in 7.5 mL blood) were enrolled in this study and intact and apoptotic CTCs were measured via the CellSearch® system. A cut-off analysis was performed using Youden's J statistics to differentiate between CTC change in the two groups. Here, 64 (59.3%) patients showed stable disease or partial response vs. 44 (40.7%) presenting disease progression. Median overall survival was 23 (range: 4-92) vs. 7 (2-43) months (p < 0.001). Median intact CTC count at enrollment was 15.0 (5-2760) vs. 30.5 (5-200000) cells (p = 0.39) and 2.5 (0-420) vs. 8.5 (0-15000) cells after one cycle of systemic therapy (p = 0.001). Median apoptotic CTC count at enrollment was 10.5 (0-1500) vs. 9 (0-800) cells (p = 0.475) and 1 (0-200) vs. 3 (0-250) cells after one cycle of systemic therapy (p = 0.01). A 50% reduction in baseline apoptotic CTC count represents the optimal cut-off to differentiate between therapy response and disease progression. An apoptotic CTC reduction of ≤10% is 74% specific for early disease progression.

Atezolizumab for use in PD-L1-positive unresectable, locally advanced or metastatic triple-negative breast cancer.

Since the US FDA-approval of the first immune checkpoint inhibitor, anticytotoxic T-lymphocyte antigen-4 monoclonal antibody ipilimumab, for metastatic melanoma on 28 March 2011, another six agents have been granted use among a multitude of tumors, including renal cell cancer, Hodgkin lymphoma, urothelial carcinoma and non-small-cell lung cancer. The first anti-programmed cell death ligand-1 monoclonal antibody to receive the FDA approval, atezolizumab (Tecentriq®), has yielded promising results among international Phase III trials in triple-negative breast cancer and small-cell lung cancer, expanding the field of cancer immunotherapies. Herein, we review the pharmacodynamic and pharmacokinetic properties of atezolizumab, its safety and efficacy data from early clinical trials and summarize data from Phase III IMpassion130 trial, prompting FDA and EMA approval of atezolizumab in metastatic triple-negative breast cancer. Finally, implications for clinical use and ongoing research will be briefly discussed.

Diagnosis and Therapy of Triple-Negative Breast Cancer (TNBC) - Recommendations for Daily Routine Practice.

The rapid increase in knowledge in tumour biology and tumour pathogenesis of triple-negative breast cancer (TNBC) has resulted in new therapeutic approaches and new therapeutic concepts for treatment. For years, TNBC has been considered to be a difficult-to-treat tumour due to its generally aggressive tumour biology and in view of limited therapeutic options. The risk of recurrence and metastasis is higher than in the case of other breast cancer subtypes of the same stage. In addition to surgery and radiation in the curative situation, systemic chemotherapy with anthracyclines and/or taxanes is still the therapy of choice. New therapeutic approaches are based on the knowledge that TNBC is a molecularly very heterogeneous disease. Research groups are working to classify TNBC better and better on a molecular level and use this molecular subtyping as the basis for new therapeutic strategies. The most promising new approaches and considerations regarding the therapy of TNBCs are shown below. In addition, the current therapeutic strategies are discussed using a fictitious case history, taking the current data and the resultant therapeutic consequence into account.

Mismatch Repair Deficiency Drives Durable Complete Remission by Targeting Programmed Death Receptor 1 in a Metastatic Luminal Breast Cancer Patient.

BACKGROUND: In the field of breast cancer tumor biology, triple-negative breast cancer patients are the main focus of current clinical trials exploring the use of immune checkpoint inhibitors due to higher frequencies of somatic mutations, neoantigens, and resulting tumor-specific T-cell reactivity. CASE REPORT: Here, we present the case of a 66-year-old woman with metastatic luminal breast cancer that rapidly responded to monotherapy with pembrolizumab, a monoclonal anti-PD-1 antibody. This patient obtained a partial clinical response within the first cycle of treatment and an ongoing durable complete remission after 12 weeks. Except for a transient immune-related thyreoiditis, there were no side effects observed offering remarkable quality of life to the patient. To evaluate the underlying mechanisms, we performed immunohistochemistry, explored the mutational landscape by whole-exome sequencing, and identified potential T-cell epitopes by prediction of neoantigens with high affinity binding to one of the patient's HLA. Briefly, we found a strong infiltration of CD8+ T cells without staining for PD-L1 in the tumor stroma. Exome sequencing revealed an enormous frequency of somatic and tumor-specific alterations, mainly C>T/G>A transitions. The mutational pattern was further linked to genome instability and deficient mismatch repair supported by the loss of MSH6 protein expression and therefore leading to susceptibility to immune checkpoint blockade. CONCLUSION: Within the overall goal to establish operating procedures for breast cancer immunotherapy, we propose to re-evaluate testing for deficient mismatch repair and to further intensify the search for biomarkers predictive for the success of immune checkpoint modulation including all tumor biologic subtypes of breast cancer.

Targeted and immuno-biology driven treatment strategies for triple-negative breast cancer: current knowledge and future perspectives.

Introduction: Accounting for about 15% of breast cancer patients, triple-negative breast cancer (TNBC) is responsible for 25% of disease related deaths, more frequent distant spread and visceral metastasis. However, improving survival in TNBC failed and primary resistance, immunological ignorance and tumor heterogeneity limit clinical activity of novel therapies. In view of recent molecular, genetic and immunologic insights, this review aims to describe the current status of immunological and targeted treatments from a hypothesis driven perspective. Areas covered: Recent preclinical studies and ongoing clinical trials for immune directed and targeted treatments of TNBC are summarized, including immune-checkpoint blockade, resistance mechanisms, inhibition of poly (ADP-ribose) polymerase (PARP), combinatorial strategies as well as preclinical, hypothesis generating studies. Expert commentary: Sustained responses have been observed with immune-checkpoint blockade and PARP inhibitors demonstrated remarkable efficacy in germline BRCA mutated TNBC. In order to generate clinical success of many other, to date ineffective, targeted and immune therapies, the integration of multidimensional, large amounts of data, will be essential and likely accelerate treatment progress of TNBC.

Use of complementary and integrative medicine among German breast cancer patients: predictors and implications for patient care within the PRAEGNANT study network.

PURPOSE: The present study aims to analyze a cohort of advanced breast cancer patients in Germany to assess their interest in complementary and alternative medicine (CAM) and patient's use of most frequent CAM methods. PATIENTS AND METHODS: Based on the PREGNANT real-time breast cancer registry which is a multicenter study in Germany, questionnaires of 580 patients with advanced breast cancer were evaluated. The implemented questionnaire for CAM asked for general interest in CAM and for patient's use of different CAM methods at present and in the past. The interest and application of CAM were analyzed for association with patients' characteristics such as tumor, patient, and therapy characteristics. RESULTS: In total, 436 out of 580 (75%) patients claimed to be interested in CAM. Further, interest in CAM is significantly correlated with younger age and absence of metastasis at the time of diagnosis. Multivariate analysis confirmed the patient's age and distant disease status at the time of diagnosis as related to interest in CAM. A total of 56.4% of patients applied any CAM method in the past. Moreover, with increasing lines of therapies, the more frequent use of CAM was observed. Hereby, praying, vitamin supplements, and other food supplements were most frequently applied. CONCLUSION: Our data demonstrate high overall interest and frequent use of CAM in advanced breast cancer patients supporting a strong demand of breast cancer patients for complementary counseling and treatments additional to the established cancer therapies. It is indispensable to implement counseling and evidence-based complementary treatments into clinical routine of cancer centers and to adapt postgraduate medical education, respectively.

Exam preparation course in obstetrics and gynecology for the German Medical State Examination: proof of concept and implications for the recruitment of future residents.

OBJECTIVES: Today´s written part of the medical state examination requires students to retrieve a comprehensive amount of knowledge in a limited period of time. Therefore, the main study objectives were to implement and to evaluate a two-day exam preparation course for the German Medical State Examination in obstetrics and gynecology. The project evaluation focused on acceptability, satisfaction and the gain of knowledge for the participants of such a face-to-face course. STUDY DESIGN: The two-day intensive training for senior medical students offered a review of the entire exam-relevant content in the field of obstetrics and gynecology in combination with interactive discussions along selected exam questions. Skill gains were assessed using pre- and post-course multiple choice tests. In addition, a qualitative questionnaire assessed attitudes and satisfaction of course participants. RESULTS: A total of 101 fifth year senior medical students from Heidelberg University Medical School participated in the two pilot courses (summer 2014 and winter 2015). Pre- and post-course tests showed a significant skill-gain from 14.9 to 18.0 points [of a maximum of 20; pre-post difference 95 % CI (2.21; 3.98), t test: p < 0.001]. Furthermore, the qualitative results showed high satisfaction with the course, with an average Likert scale grading of 5.63 (2014) and 5.44 (2015) on a scale from 1 ("extraordinary bad") to 6 ("extraordinary good"). CONCLUSIONS: This study shows that a two-day intensive course in obstetrics and gynecology is feasible, effective and highly appreciated by senior medical students preparing for the Second German Medical State Examination. It further suggests surplus value for academic clinical departments to recruit future residents. Methods and tools presented in this paper are intended to inspire and guide clinical colleagues in implementing the format at their respective universities.

Mucin 1-specific B cell immune responses and their impact on overall survival in breast cancer patients.

Considering the diverse functions of B cells, responses to tumor-associated antigens (TAA) have been thought to be the main source of B cell-mediated antitumor immunity. Polymorphic epithelial mucin (MUC1) is considered one of the most specific TAA in patients with breast cancer. The present study aims to dissect the level and subclasses of naturally occurring anti-MUC1 antibodies in regard to tumor biologic parameters, clinical characteristics and overall survival. In 288 primary, non-metastatic breast cancer patients, pretreatment serum levels of anti-MUC1 immunoglobulin G (IgG) and its subclasses G1-4 as well as immunoglobulin M (IgM) were analyzed via ELISA. With respect to overall survival (Kaplan-Meier analysis), tumor biologic parameters as hormone receptor status, human epidermal growth factor receptor 2 (Her2), Ki-67 expression and tumor grading have been correlated as well as clinical characteristics as nodal involvement, tumor stage and patients' age at the time of diagnosis. Median follow-up time was 148 mo (IQR: 73.1-158.5 mo). A significant increase in IgG antibody titers was correlated highly significantly with an improved overall survival of patients. In multivariate analysis, total IgG proved to be an independent prognostic marker for overall survival (p = 0.002). IgG subclass analysis did not reveal any correlation of IgG1, IgG3 and IgG4 levels with overall survival, while increased immunoglobulin G2 (IgG2) values, although statistically not significant, tended to correlate with prolonged patient survival. MUC1-specific IgM antibodies were shown not to be predictive of overall survival. Altogether, humoral immune responses appear to play a crucial part in the tumor immunity of breast cancer patients. The present data confirms the positive impact of tumor-specific IgG on prolonged overall survival in breast cancer patients. MUC1-antibody testing might be a useful tool to identify high-risk patients who may need adjuvant therapy and potentially might benefit from MUC1-directed immunotherapy.