Effects of letrozole on serum estradiol and estrone in postmenopausal breast cancer patients and tolerability of treatment: a prospective trial using a highly sensitive LC-MS/MS (liquid chromatography-tandem mass spectrometry) method for estrogen measurement.

PURPOSE: To analyze serum estradiol (E2) and estrone (E1) during letrozole treatment and their association to Quality of Life (QoL) and side-effects. METHODS: Postmenopausal breast cancer patients starting adjuvant letrozole were eligible. Serum samples were taken at baseline, three, and 12 months. E2 and FSH were measured with routine chemiluminescent immunoassays. E2 and E1 were analyzed after trial completion with a highly sensitive liquid chromatography-tandem mass spectrometry method (LC-MS/MS) with lower limits of quantification (LLOQ) of 5 pmol/L. QoL was measured at baseline and at 12 months with the EORTC QLQ-C30 and QLQ-BR23 and the Women's Health questionnaires, and menopause-related symptoms with the modified Kupperman Index. RESULTS: Of 100 screened patients 90 completed the trial. Baseline mean LC-MS/MS E2 and E1 were 12 pmol/L (range < 5-57) and 66 pmol/L (< 5-226), respectively. E2 levels measured by immunoassay and LC-MS/MS showed no correlation. E2 and E1 were completely suppressed by letrozole except for one occasion (E1 11 pmol/L at 3 months). Pain, side effects of systemic therapy, vasomotor symptoms, joint and muscle aches, and vaginal dryness increased during letrozole treatment. A high baseline E2 was significantly associated with increased aching joints and muscles, but not with the other side effects. CONCLUSIONS: Letrozole supresses E2 and E1 completely below the LLOQ of the LC-MS/MS in postmenopausal women. High pre-treatment E2 levels were associated with more joint and muscle pain during letrozole. Automated immunoassays are unsuitable for E2 monitoring during letrozole therapy due to poor sensitivity.

Well-being trajectories in breast cancer and their predictors: A machine-learning approach.

OBJECTIVE: This study aimed to describe distinct trajectories of anxiety/depression symptoms and overall health status/quality of life over a period of 18 months following a breast cancer diagnosis, and identify the medical, socio-demographic, lifestyle, and psychological factors that predict these trajectories. METHODS: 474 females (mean age = 55.79 years) were enrolled in the first weeks after surgery or biopsy. Data from seven assessment points over 18 months, at 3-month intervals, were used. The two outcomes were assessed at all points. Potential predictors were assessed at baseline and the first follow-up. Machine-Learning techniques were used to detect latent patterns of change and identify the most important predictors. RESULTS: Five trajectories were identified for each outcome: stably high, high with fluctuations, recovery, deteriorating/delayed response, and stably poor well-being (chronic distress). Psychological factors (i.e., negative affect, coping, sense of control, social support), age, and a few medical variables (e.g., symptoms, immune-related inflammation) predicted patients' participation in the delayed response and the chronic distress trajectories versus all other trajectories. CONCLUSIONS: There is a strong possibility that resilience does not always reflect a stable response pattern, as there might be some interim fluctuations. The use of machine-learning techniques provides a unique opportunity for the identification of illness trajectories and a shortlist of major bio/behavioral predictors. This will facilitate the development of early interventions to prevent a significant deterioration in patient well-being.

Predictive factors for prolonged sick leave in breast cancer patients treated with adjuvant therapies: a retrospective registry study.

BACKGROUND: Being able to work during and after breast cancer treatments is important for patients to have a sense of normalcy, financial security, and improved quality of life, and for society due to the economic burden of sick leave. Factors influencing the length of sick leave can be sociodemographic factors, workplace adaptations, recurrences, symptoms, and type of treatment. The aim of this study is to analyse factors associated with prolonged sick leave after adjuvant breast cancer treatments. METHODS: The population of this registry study consists of 1333 early breast cancer patients diagnosed and treated in Helsinki University Hospital between 2016 and 2018. Data on patient demographics, disease characteristics, treatment, and healthcare resource utilization were obtained from Helsinki University Hospital and data on income level and sick leave were obtained from Kela sickness benefits registry. Prolonged sick leave was determined as the patient accumulating 30 or more reimbursed sick leave days during a 60-day follow-up period after the end of active oncological treatment. Univariate analysis and multivariate analysis were conducted. RESULTS: A total of 26% of the patients in this study were on sick leave for 30 or more days after the active treatments ended. Study findings show that chemotherapy, triple-negative breast cancer, reconstructive surgery, amount of outpatient visits, and income are associated with prolonged sick leave. Independent predictors of prolonged sick leave were treatment line, number of outpatient contacts, reconstruction, and triple-negative breast cancer. CONCLUSIONS: Our study shows that prolonged sick leave affects a substantial number of working-age women with early breast cancer. Independent predictors for prolonged sick leave were all treatment-related. Targeted support for treatment-related side-effects already during the treatment period could lead to better recovery and earlier return to work.

Digital solution in the follow-up of early breast cancer a randomized study.

BACKGROUND: After primary treatment, patients with early breast cancer (EBC) are followed-up for at least 5 years. At the Helsinki University Hospital (HUS) surveillance includes appointments at 1, 3 and 5 years, and between pre-planned visits a phone call service operated by a nurse practitioner for counseling about symptoms related to side-effects or potential recurrence. In 2015 HUS launched a digital solution for cancer patients. This study was designed to find out patient preference, Health related (HR) quality of life (QOL) and satisfaction with a digital solution compared to a phone call service during the first year of follow-up. MATERIAL AND METHODS: Patients with EBC were randomized at the final visit of radiotherapy to surveillance by phone calls or by the digital Noona solution during the first year outside pre-planned visits. After six months the groups were crossed over to the other arm. Primary endpoint was patient preference for either follow-up method among those who had contacted the study nurse at least once by both phone service and digital solution. RESULTS: Out of the 765 patients randomized, 142 had contacted the hospital with both methods and were eligible for inclusion in the analyses of the present study. Out of the 142 patients, 56 preferred phone calls, 43 the digital solution while 43 considered both modalities equal. Preference for the digital solution was higher among patients aged 65 or less. There were no differences in HR QoL or overall satisfaction between the modalities. However, the patients rated the timeliness of response better while using the digital solution. CONCLUSION: Of the patients 30% preferred the digital solution, 40% phone calls while 30% found them equal as the primary follow-up method for EBC during the first year outside pre-planned visits. There is a need to include also digital solutions in surveillance of EBC. CLINICALTRIALS.GOV IDENTIFIER: NCT04980989.

Personalized Risk Analysis to Improve the Psychological Resilience of Women Undergoing Treatment for Breast Cancer: Development of a Machine Learning-Driven Clinical Decision Support Tool.

BACKGROUND: Health professionals are often faced with the need to identify women at risk of manifesting poor psychological resilience following the diagnosis and treatment of breast cancer. Machine learning algorithms are increasingly used to support clinical decision support (CDS) tools in helping health professionals identify women who are at risk of adverse well-being outcomes and plan customized psychological interventions for women at risk. Clinical flexibility, cross-validated performance accuracy, and model explainability permitting person-specific identification of risk factors are highly desirable features of such tools. OBJECTIVE: This study aimed to develop and cross-validate machine learning models designed to identify breast cancer survivors at risk of poor overall mental health and global quality of life and identify potential targets of personalized psychological interventions according to an extensive set of clinical recommendations. METHODS: A set of 12 alternative models was developed to improve the clinical flexibility of the CDS tool. All models were validated using longitudinal data from a prospective, multicenter clinical pilot at 5 major oncology centers in 4 countries (Italy, Finland, Israel, and Portugal; the Predicting Effective Adaptation to Breast Cancer to Help Women to BOUNCE Back [BOUNCE] project). A total of 706 patients with highly treatable breast cancer were enrolled shortly after diagnosis and before the onset of oncological treatments and were followed up for 18 months. An extensive set of demographic, lifestyle, clinical, psychological, and biological variables measured within 3 months after enrollment served as predictors. Rigorous feature selection isolated key psychological resilience outcomes that could be incorporated into future clinical practice. RESULTS: Balanced random forest classifiers were successful at predicting well-being outcomes, with accuracies ranging between 78% and 82% (for 12-month end points after diagnosis) and between 74% and 83% (for 18-month end points after diagnosis). Explainability and interpretability analyses built on the best-performing models were used to identify potentially modifiable psychological and lifestyle characteristics that, if addressed systematically in the context of personalized psychological interventions, would be most likely to promote resilience for a given patient. CONCLUSIONS: Our results highlight the clinical utility of the BOUNCE modeling approach by focusing on resilience predictors that can be readily available to practicing clinicians at major oncology centers. The BOUNCE CDS tool paves the way for personalized risk assessment methods to identify patients at high risk of adverse well-being outcomes and direct valuable resources toward those most in need of specialized psychological interventions.

Associations between Physical Exercise, Quality of Life, Psychological Symptoms and Treatment Side Effects in Early Breast Cancer.

Background: Identifying and understanding modifiable factors for the well-being of cancer patients is critical in survivorship research. We studied variables associated with the exercise habits of breast cancer patients and investigated if the achievement of exercise recommendations was associated with enhanced quality of life and/or psychological well-being. Material and Methods. 311 women from Finland, Portugal, Israel, and Italy receiving adjuvant therapy for stage I-III breast cancer answered questions about sociodemographic factors and physical exercise. Quality of life was assessed by the EORTC C30 and BR23 questionnaires. Anxiety and depression were evaluated using the HADS scale. Results: At the beginning of adjuvant therapy and after twelve months, 32% and 26% of participants were physically inactive, 27% and 30% exercised between 30 and 150 minutes per week, while 41% and 45% exercised the recommended 150 minutes or more per week. Relative to other countries, Finnish participants were more likely to be active at baseline and at twelve months (89% vs. 50%, p < 0.001 and 87% vs. 64%, p < 0.001). Participants with stage I cancer were more likely to be active at twelve months than those with a higher stage (80% vs. 70%,p < 0.05). The inactive participants reported more anxiety (p < 0.05) and depression (p < 0.001), lower global quality of life (p < 0.001), and more side effects (p < 0.05) than the others at twelve months. Accordingly, those who remained inactive or decreased their level of exercise from baseline to twelve months reported more anxiety (p < 0.01) and depression (p < 0.001), lower global quality of life (p < 0.001), and more side effects (p < 0.05) than those with the same or increased level of exercise. Conclusion: For women with early breast cancer, exercise was associated with a better quality of life, less depression and anxiety, and fewer adverse events of adjuvant therapy. Trial registration number: NCT05095675. Paula Poikonen-Saksela on behalf of Bounce consortium (https://www.bounce-project.eu/).

Monitoring serum estradiol levels in breast cancer patients during extended adjuvant letrozole treatment after five years of tamoxifen: a prospective trial.

PURPOSE: To analyze whether monitoring serum estradiol (E2) levels using a highly sensitive and specific liquid chromatography tandem mass spectrometry (LC-MS/MS) method may identify patients with AI failure with E2 levels below the lower limit of quantification (LLOQ) after schwitching from tamoxifen to letrozole. METHODS: In a prospective study of breast cancer patients switching to letrozole treatment after previous tamoxifen, plasma estrogen levels were measured at baseline and after 3- and 12-months using LC-MS/MS. RESULTS: Forty-six patients were classified postmenopausal and entered into the final analysis. Thirty-nine (85%) patients had three- and 12-month E2 concentrations below the LLOQ (5 pmol/L). In the seven patients classified as AI-failures during letrozole treatment, serum E2-MS level rose above 5 pmol/L at 3 months with a mean E2-MS 77.5 pmol/L or 12 months with a mean E2-MS 21 pmol/L. None of the baseline variables i.e., age at diagnosis, age at study entry, age at menarche, BMI, endometrial thickness, total ovarian volume, baseline FSH, E2-IA, or E2-MS were significantly associated with the risk of AI failure in logistic regression. E2 levels at baseline measured by E2-IA did not significantly correlate to the levels measured by E2-MS. CONCLUSIONS: There is a relatively high risk of inadequate estrogen suppression in patients who switch from tamoxifen treatment to AIs. The use of sensitive and specific assays, such as LC-MS/MS methods, to monitor estrogen levels during AI treatment is essential to minimize the risk of a proceeding inefficient endocrine therapy.

Cognitive, emotional, and behavioral mediators of the impact of coping self-efficacy on adaptation to breast cancer: An international prospective study.

OBJECTIVE: The main objective of this prospective multicenter study was to examine whether illness representations of control, affect, and coping behaviors mediate the effects of self-efficacy to cope with cancer on psychological symptoms and overall quality of life, in breast cancer patients. METHOD: Data from 413 women (Mean age = 54.87; SD = 8.01), coming from four countries (i.e., Finland, Israel, Italy, Portugal), who received medical therapy for their early breast cancer, were analyzed. Coping self-efficacy was assessed at baseline. Potential mediators were assessed three months later, and outcomes after six months. RESULTS: Coping self-efficacy was related to all mediators and outcomes. Illness representations of treatment control, positive and negative affect, and certain coping behaviors (mostly, anxiety preoccupation) mediated the effects of coping self-efficacy. Coping self-efficacy was related to each outcome through a different combination of mediators. CONCLUSIONS: Coping self-efficacy is a major self-regulation factor which is linked to well-being through multiple cognitive, emotional, and behavioral pathways. Enhancement of coping self-efficacy should be a central intervention goal for patients with breast cancer, towards promotion of their well-being.

Expression of markers of stem cell characteristics, epithelial-mesenchymal transition, basal-like phenotype, proliferation, and androgen receptor in metaplastic breast cancer and their prognostic impact.

BACKGROUND: Metaplastic breast cancer (MpBC) is a heterogeneous subtype of invasive mammary carcinoma associated with epithelial-mesenchymal transition (EMT) and cancer stem cell characteristics. Data regarding prognostic markers and potentially actionable targets for therapy are still limited. The present study aimed to characterize the immunohistochemical landscape of this rare malignancy and to identify potential prognostic factors and targets for therapy. MATERIAL AND METHODS: A total of 75 patients diagnosed with MpBC over a 15-year period were included in the study. We performed immunohistochemical analyses for Ki-67 (MIB-1), epidermal growth factor receptor (EGFR), cytokeratin 5/6, vimentin, CD44, and androgen receptor (AR) and correlated their expression with clinicopathologic features and clinical outcomes. The p-values for survival analyses were corrected for multiple testing (threshold 0.01). RESULTS: Most tumors expressed CK5/6 (73%), EGFR (59%), CD44 (81%), and vimentin (87%). Eighty-nine percent had a high Ki-67 index. Eighty-four percent were classified as basal-like (CK 5/6 or EGFR positive). AR was expressed in 21% of the tumors. The basal-like phenotype was significantly (p = 0.009) associated with inferior disease-free (DFS) and breast-cancer-specific overall survival (BCOS) with borderline significance (p = 0.01). In addition, a low Ki-67 index was associated with improved DFS (p = 0.033) and BCOS (p = 0.03). CONCLUSION: Most MpBCs express basal markers (CK5/6, EGFR), epithelial-mesenchymal transition marker vimentin, and the stem cell marker CD44. Expression of basal-like markers was significantly related to inferior DFS. All the 11 patients with a lack of expression of basal markers survived without relapse.

Neuroendocrine Breast Carcinomas Share Prognostic Factors with Gastroenteropancreatic Neuroendocrine Tumors: A Putative Prognostic Role of Menin, p27, and SSTR-2A.

OBJECTIVES: Due to the rarity of breast carcinomas with neuroendocrine features (NEBC), the knowledge on their biology is very limited but the identification of their biology and prognostic factors is essential to evaluate both pathogenesis and possible targeted treatment options. We assessed the expression of the well-characterized prognostic factors of gastroenteropancreatic neuroendocrine tumors (GEP-NET) in NEBC. METHODS: We assessed the immunohistochemical expression of neuron-specific enolase (NSE), thymidylate synthase (TS), p27, CD56, menin, and somatostatin receptor type 2A (SSTR-2A) in a series of 36 NEBC and 45 invasive ductal carcinomas (IDC). RESULTS: Nuclear and cytoplasmic TS, nuclear and cytoplasmic NSE, and nuclear p27 had significant overexpression in NEBC compared with IDC (for all, p < 0.01). In NEBC, cytoplasmic SSTR-2A expression was associated with excellent distant disease-free survival (p = 0.013), cytoplasmic menin expression with poorer relapse-free survival (p = 0.022), and nuclear p27 with longer breast cancer-specific survival (p = 0.022). CONCLUSIONS: There is a striking similarity in GEP-NET and NEBC regarding prognostic factors. GEP-NET and NEBC also appear to show similar expression patterns of the studied markers, while there are notable differences compared to IDC. Due to the wide expression of SSTR-2A, the treatment option with somatostatin analogs in NEBC should be evaluated.

Metaplastic carcinoma of the breast: Prognosis and response to systemic treatment in metastatic disease.

BACKGROUND: Metaplastic breast carcinomas (MpBCs) are rare, aggressive breast cancers. Due to the scant literature of this disease most guidelines do not give recommendation for this entity. The aim of the study was to review the clinicopathologic features, treatment, and outcomes of the patients with MpBC treated at our institution. MATERIAL AND METHODS: We searched databases for patients with histologically confirmed MpBC from 2002 to 2016. RESULTS: A total of 78 patients with MpBC were included in the study. All histological material was reviewed by an experienced breast pathologist. Most tumors were grade 3 (83%) and triple negative (85%). Eighty-two percent were node negative. Sixty-four percent received adjuvant chemotherapy. The 5-year disease free survival was 63% and 5-year breast cancer specific overall survival was 61%. Tumor size and mixed metaplastic histology were associated with worse outcome in this patient group. One third of the patients (n = 28) had metastatic disease at initial presentation or developed metastases at follow-up. The lungs were the most common site of first distant recurrence. Half (n = 14) of these patients received palliative chemotherapy. Of those only 6% (n = 2) had partial response and 18% had stable disease as best response to treatment. The median overall survival time with metastatic disease was only 3.4 months. CONCLUSION: MpBC is an aggressive type of breast cancer with poor outcome despite low nodal involvement and aggressive local and systemic therapy. Tumor response to palliative systemic chemotherapy remains poor for MpBC patients.

Primary neuroendocrine breast carcinomas are associated with poor local control despite favourable biological profile: a retrospective clinical study.

BACKGROUND: Breast carcinomas with neuroendocrine features (NEBC) are a very rare entity of mammary neoplasms, WHO classification of which has recently been revised. There are very limited data available about the clinical behaviour and treatment options of NEBC. METHODS: We collected retrospectively patients with NEBC from Oulu and Helsinki University Hospitals in 2007-2015. There were 43 NEBC cases during the period. RESULTS: The incidence of NEBC from all breast cancers varied from 0.1% in Helsinki to 1.3% in Oulu. The mean tumor size was 2.2 cm and 23 patients (55.8%) had no lymph node metastases when diagnosed. In total, 4 patients (9.3%) had distant metastases at the time of diagnosis. High estrogen receptor (ER) expression was observed in 41 (97.7%) patients. When non-metastatic NEBC were compared to a prospective set of ductal carcinomas (n = 506), NEBC were more often HER2 negative (p = 0.046), ER positive (p = 0.0062) and the NEBC patients were older (p < 0.0005) than patients with ductal carcinomas. Plasma chromogranin A correlated only to higher age at diagnosis (p = 0.0028). Relapse-free survival (p = 0.0013), disease-free survival (p = 0.024) and overall survival (p = 0.0028) favoured ductal carcinomas compared to NEBC, while no difference was observed in distant disease-free survival or in breast cancer-specific survival. CONCLUSIONS: There is remarkable variation in the incidence of NEBC in Finland, which is likely to be explained by differences in the use of neuroendocrine marker immunostainings. Poor local control and worse overall survival may be linked to the more aggressive biology of the disease, despite its association with apparently indolent prognostic factors.

CHEK2 c.1100delC mutation is associated with an increased risk for male breast cancer in Finnish patient population.

BACKGROUND: Several susceptibility genes have been established for female breast cancer, of which mutations in BRCA1 and especially in BRCA2 are also known risk factors for male breast cancer (MBC). The role of other breast cancer genes in MBC is less well understood. METHODS: In this study, we have genotyped 68 MBC patients for the known breast or ovarian cancer associated mutations in the Finnish population in CHEK2, PALB2, RAD51C, RAD51D, and FANCM genes. RESULTS: CHEK2 c.1100delC mutation was found in 4 patients (5.9%), which is significantly more frequent than in the control population (OR: 4.47, 95% CI 1.51-13.18, p = 0.019). Four CHEK2 I157T variants were also detected, but the frequency did not significantly differ from population controls (p = 0.781). No RAD51C, RAD51D, PALB2, or FANCM mutations were found. CONCLUSIONS: These data suggest that the CHEK2 c.1100delC mutation is associated with an increased risk for MBC in the Finnish population.

[Male breast cancer]. / Miehen rintasyöpä.

Breast cancer is rare in men. Diagnosis of the illness may be delayed due to the fact that the doctor and the patient fail to suspect it. Male breast cancer is treated mainly on the same principles as female breast cancer. A man affected with breast cancer should always be directed to genetic testing, as inherited mutations increasing the risk of developing cancer are more common than in female breast cancer. Most breast cancers in men are hormone receptor positive. Among hormone treatments, the antiestrogen tamoxifen exhibits the best efficacy both in early-state and advanced cases.

Current follow-up of a breast cancer patient.

The number of patients with breast cancer is on the rise, which leads to an increasing number of patients in need of follow-up and support for recovery from treatments. The disease will recur in one out of five patients. With the exception of imaging of the breasts carried out at intervals of 1 to 2 years, frequent appointments or imaging have not been shown to be beneficial for the prognosis. Follow-up care of breast cancer is well suited to be carried out by the nursing staff. The status of mobile applications developed for patient monitoring as part of the surveillance is becoming more clear.

[Treatment of disseminated breast cancer]. / Levinneen rintasyövän hoito.

Although several effective drugs have in recent years been introduced for the treatment of disseminated breast cancer, it is still an incurable illness. Many patients live a fairly normal life with their illness for a long time, and some of them are able to continue working in spite of the therapies. Factors considered in tailoring the treatment include tumor subtype, extent of the disease, symptoms, previous treatments and the achieved treatment outcome, and adverse effects of the treatments.

[Adjuvant drug therapies for breast cancer]. / Rintasyövän liitännäislääkehoidot.

Most breast cancers are hormone receptor positive and exhibit a slow growth pattern. Based on biological properties, breast cancers are divided into four different biological subtypes. Furthermore, these subtypes are indicative of the risk of recurrence, which is also influenced by the size of the tumor and extension to lymph nodes. Postoperative adjuvant drug therapy is chosen on the basis of the biological type. Chemotherapy can be used in all subtypes. Hormonal therapies are used exclusively for the treatment of hormone receptor positive breast cancer. Trastuzumab antibody belongs to the treatment of the HER2 positive subtype.

Respiratory complex I regulates dendritic cell maturation in explant model of human tumor immune microenvironment.

BACKGROUND: Combining cytotoxic chemotherapy or novel anticancer drugs with T-cell modulators holds great promise in treating advanced cancers. However, the response varies depending on the tumor immune microenvironment (TIME). Therefore, there is a clear need for pharmacologically tractable models of the TIME to dissect its influence on mono- and combination treatment response at the individual level. METHODS: Here we establish a patient-derived explant culture (PDEC) model of breast cancer, which retains the immune contexture of the primary tumor, recapitulating cytokine profiles and CD8+T cell cytotoxic activity. RESULTS: We explored the immunomodulatory action of a synthetic lethal BCL2 inhibitor venetoclax+metformin drug combination ex vivo, discovering metformin cannot overcome the lymphocyte-depleting action of venetoclax. Instead, metformin promotes dendritic cell maturation through inhibition of mitochondrial complex I, increasing their capacity to co-stimulate CD4+T cells and thus facilitating antitumor immunity. CONCLUSIONS: Our results establish PDECs as a feasible model to identify immunomodulatory functions of anticancer drugs in the context of patient-specific TIME.

Predictors of successful neoadjuvant treatment in HER2­positive breast cancer.

The prognosis of local or locally advanced human epidermal growth factor receptor 2 (HER2)-positive breast cancer after a complete response from neoadjuvant systemic treatment (NAT) is excellent. However, some of the patients succumb to their disease, so novel predictive factors to identify these patients at risk are needed. Retrospective data from 119 patients treated at the Helsinki University Hospital Comprehensive Cancer Centre (Helsinki, Finland) were collected. All patients had in situ hybridization-confirmed HER2-positive breast cancer and underwent NAT with a curative intention. The primary tumours were relatively large, most patients had cytologically confirmed lymph node metastases and the treatments used were current regimens. A total of 63 (52.1%) patients had a pathological complete response (pCR) to neoadjuvant therapy. Achieving pCR predicted longer disease-free survival (DFS; P=0.0083) but not overall survival (P=0.061). The patients with a pCR had an estimated DFS rate of 96.8% at 5 years, compared with only 59.7% of the patients with non-pCR. Radiological complete response (CR) was associated with pCR (P=0.00033), although imaging yielded 30.4% false-negative and 36.9% false-positive results. The association between the radiological CR and pCR was more obvious in oestrogen receptor-negative tumours. Moderate (compared with strong) immunohistochemical HER2 expression predicted a lower chance of pCR (P=0.0078) and worse breast cancer-specific survival (P=0.0015). In conclusion, pCR after NAT served as an important prognostic factor in women with high-risk HER2-positive breast cancer. The patients with only moderate immunohistochemical HER2 expression had a lower chance of reaching a pCR, as well as a shorter breast cancer-specific survival.