Peroxiporins in Triple-Negative Breast Cancer: Biomarker Potential and Therapeutic Perspectives.

Triple-negative breast cancer (TNBC) remains one of the most challenging subtypes since it is initially characterized by the absence of specific biomarkers and corresponding targeted therapies. Advances in methodology, translational informatics, genomics, and proteomics have significantly contributed to the identification of therapeutic targets. The development of innovative treatments, such as antibody-drug conjugates and immune checkpoint inhibitors, alongside chemotherapy, has now become the standard of care. However, the quest for biomarkers defining therapy outcomes is still ongoing. Peroxiporins, which comprise a subgroup of aquaporins, which are membrane pores facilitating the transport of water, glycerol, and hydrogen peroxide, have emerged as potential biomarkers for therapy response. Research on peroxiporins reveals their involvement beyond traditional channeling activities, which is also reflected in their cellular localization and roles in cellular signaling pathways. This research on peroxiporins provides fresh insights into the mechanisms of therapy resistance in tumors, offering potential avenues for predicting treatment outcomes and tailoring successful TNBC therapies.

Correlation between psychological resilience and burnout syndrome in oncologists amid the Covid-19 pandemic.

PURPOSE: Oncologists are predisposed to developing burnout syndrome. Like other health care professionals worldwide, oncologists have endured additional, extreme challenges during the Covid-19 pandemic. Psychological resilience presents a potential protective mechanism against burnout. This cross-sectional study examines whether psychological resilience eased burnout syndrome among Croatian oncologists during the pandemic. METHODS: An anonymized self-reporting questionnaire was electronically distributed by the Croatian Society for Medical Oncology to 130 specialist and resident oncologists working in hospitals. Available for completion from September 6-24, 2021, the survey comprised demographic questions; the Oldenburg Burnout Inventory (OLBI), covering exhaustion and disengagement; and the Brief Resilience Scale (BRS). The response rate was 57.7%. RESULTS: Burnout was moderate or high for 86% of respondents, while 77% had moderate or high psychological resilience. Psychological resilience was significantly negatively correlated with the OLBI exhaustion subscale (r = - .54; p < 0.001) and the overall OLBI score (r = - .46; p < 0.001). Scheffe's post hoc test showed that oncologists with high resilience scored significantly lower on the overall OLBI (M = 2.89; SD = 0.487) compared to oncologists with low resilience (M = 2.52; SD = 0.493). CONCLUSION: The findings thus indicate that oncologists with high psychological resilience are at significantly lower risk of developing burnout syndrome. Accordingly, convenient measures to encourage psychological resilience in oncologists should be identified and implemented.

HER2 Low Breast Cancer: A New Subtype or a Trojan for Cytotoxic Drug Delivery?

Despite the great progress made in the understanding of the biological behavior of certain types of invasive breast cancer, there is still no single histological or molecular classification that encompasses such diversity and accurately predicts the clinical course of distinct breast cancer subtypes. The long-lasting classification of breast cancer as HER2-positive vs. HER2-negative has recently come into question with the discovery of new antibody drug conjugates (ADC), which are proven to be remarkably efficient in treating HER2-low breast cancer. The HER2-low paradigm has challenged the traditional understanding of HER2 overexpression and emphasized the need for more robust HER2 testing in order to encompass HER2 intratumoral heterogeneity and spatial distribution more accurately. It is yet to be seen if low HER2 will remain merely a marker of HER2-equipped tumors targetable with ADCs or if distinctive molecular and phenotypic groups within HER2-low tumors will eventually be discerned.

The First Wave of the COVID-19 Pandemic and Its Impact on the Level of Distress in Patients with Breast Cancer, a Multicentric Study.

BACKGROUND: Information on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), later termed coronavirus disease (COVID-19), first emerged by the end of 2019. As the pandemic spread, cancer patients were immediately recognized as a high-risk population with regard to COVID-19 infection. Moreover, epidemiological measures, like social distancing and lockdowns, additionally burdened patients with cancer. Even outside pandemic breast cancer patients are prone to psychological distress with prevalence ranging approximately 20-40%. This multicentric study aimed to examine the impact of COVID-19 pandemic on the level of distress among breast cancer patients in Croatia while the first wave of COVID-19 pandemic. SUBJECTS AND METHODS: Fife hundred forty-five breast cancer patients were offered to participate in the study. A total of two hundred and one patient, with disease stages ranging I-IV, completed the questionnaire. The questionnaire consisted of disease and socio-demographic characteristics followed by the Distress Thermometer and a problem list. The cut off value of 4 was used to define the high level of distress within Distress Thermometer. RESULTS: High distress level was reported in 54.2% of patients. The most significant problems reported by the participants of our study affected emotions, causing worry, sadness, depression, fear, and nervousness. Additionally, specific practical problems emerged (e.g., child care, housing, and work/school), most probably partly due to the lockdowns and social distancing. Interestingly enough, none of the socio-demographic or disease characteristics were linked to the level of distress. CONCLUSIONS: During first wave of COVID-19 pandemic more than half of breast cancer patients, undergoing active oncologic treatment, experienced a high level of distress. Therefore, distress driven by the COVID-19 pandemic should be promptly addressed and additional psychological and social support, targeting specific practical and emotional problems, should be provided for those patients. All the more so as global COVID-19 pandemic far exceeded the duration of the first wave.

OXALIPLATIN INDUCED PULMONARY FIBROSIS: A CASE REPORT.

Oxaliplatin is part of the standard chemotherapy regimens for treating colorectal carcinoma. Pulmonary fibrosis is a serious but rare side effect of oxaliplatin treatment, which resulted in patient death in more than half of the reported cases. The precise pathophysiological mechanism of this phenomenon has not been clarified yet. Analysis of the reported cases strongly suggests that early diagnosis and immediate corticosteroid treatment are crucial for better prognosis. Here we report a case of pulmonary fibrosis related to the FOLFOX regimen in a patient with early colorectal carcinoma.

Association of Breast Cancer Symptoms with Patients' Quality of Life and Depression; A Croatian Cross-Sectional Study.

AIM: To find out which symptoms are the most associated with a breast cancer patients' quality of life (QoL) and depression. SUBJECTS AND METHODS: We performed this cross-sectional study from February to April 2015 at the Department of Medical Oncology, University Hospital for Tumors, Zagreb University Hospital Center "Sestre milosrdnice", Zagreb, Croatia on the sample of 147 breast cancer patients. Primary outcomes were EORTC QLQ-C30 version 3.0 Global QoL scale and Beck Depression Inventory II. RESULTS: After the adjustment for other symptoms, sociodemographic and clinical variables, fatigue (ß=-0.47, P<0.001), pain (ß=-0.24, P=0.023), and appetite loss (ß=-0.18, P=0.037) were statistically significantly correlated with QoL. Fatigue was the only symptom significantly associated with depression (ß=0.39, P=0.006). CONCLUSION: Fatigue, pain, appetite loss contributes the most to the overall breast cancer patients QoL. Although correlated, fatigue and pain contribution to lower QoL is independent from each other. Future studies should investigate whether there is an interaction between fatigue and pain changes over course of treatment. Fatigue and number of children are positively, while age and treatment in daily hospital are negatively associated with depression measured by BDI-II.

UNCOMMON SIDE EFFECTS OF SUNITINIB THERAPY IN A PATIENT WITH METASTATIC RENAL CELL CANCER: CASE REPORT.

- Sunitinib is an orally administered multikinase inhibitor. This therapy can provoke uncommon side effects such as pancytopenia, tumor lysis syndrome, cardiac disorders, thromboembolic incidents, intestinal perforation, pancreatitis, acute renal failure, etc. We report a case of a 63-year-old female admitted to the hospital due to abdominal pain, nausea, vomiting and elevated blood pressure. One month earlier, sunitinib therapy for metastatic renal cell carcinoma was initiated. During the first cycle of therapy, after three weeks of sunitinib 50 mg daily, symptoms started and she stopped taking the drug. At admission, laboratory tests revealed elevated serum and urine amylase, C-reactive protein, urea and creatinine, and lowered platelet and leukocyte counts and hemoglobin value. Urine test showed proteinuria, erythrocyturia, leukocyturia and granulated cylinder. The patient was diagnosed with acute pancreatitis grade III, acute renal failure grade II, pancytopenia and urinary infection, and was hospitalized for five days. She was treated symptomatically and with antibiotic therapy because of persistently elevated C-reactive protein and pathologic urinary sediment, which led to subjective and clinical improvement. Acute pancreatitis, renal insufficiency and pancytopenia are rarely described side effects of sunitinib therapy, and clear connection between these conditions and drug activity is not yet determined. Medical specialists who prescribe and treat patients with sunitinib should be aware of the possible occurrence of these conditions and perform regular checkups of sunitinib treated patients.

[CANCER PATIENTS FOLLOW-UP ­ CROATIAN SOCIETY FOR MEDICAL ONCOLOGY CLINICAL GUIDELINES Part IV: planocellular head and neck cancer, oesophageal cancer, gastric cancer, colorectal cancer].

Treatment of oncological patients must be based upon multidisciplinary approach, and takes place in specialized oncological centers. By the end of a specific oncological treatment further follow-up is being managed mostly by the oncologists, but the role of the general practitioners becomes more important every day and therefore should be precisely defined. Nowadays, most of the existing follow-up guidelines are not being based on prospective studies, yet on the expert's opinion of a precise oncological center or specialists. The aim of the Croatian Society of Medical Oncology (CSMO) with these recommendations is to standardize and rationalize the diagnostic procedures' algorithm in follow­up of oncological patients after primary treatment, in patients with planocellular head and neck cancer, oesophageal cancer, gastric cancer and colorectal cancer.

Neratinib after trastuzumab-based adjuvant therapy in patients with HER2-positive breast cancer (ExteNET): a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial.

BACKGROUND: Neratinib, an irreversible tyrosine-kinase inhibitor of HER1, HER2, and HER4, has clinical activity in patients with HER2-positive metastatic breast cancer. We aimed to investigate the efficacy and safety of 12 months of neratinib after trastuzumab-based adjuvant therapy in patients with early-stage HER2-positive breast cancer. METHODS: We did this multicentre, randomised, double-blind, placebo-controlled, phase 3 trial at 495 centres in Europe, Asia, Australia, New Zealand, and North and South America. Eligible women (aged ≥18 years, or ≥20 years in Japan) had stage 1-3 HER2-positive breast cancer and had completed neoadjuvant and adjuvant trastuzumab therapy up to 2 years before randomisation. Inclusion criteria were amended on Feb 25, 2010, to include patients with stage 2-3 HER2-positive breast cancer who had completed trastuzumab therapy up to 1 year previously. Patients were randomly assigned (1:1) to receive oral neratinib 240 mg per day or matching placebo. The randomisation sequence was generated with permuted blocks stratified by hormone receptor status (hormone receptor-positive [oestrogen or progesterone receptor-positive or both] vs hormone receptor-negative [oestrogen and progesterone receptor-negative]), nodal status (0, 1-3, or ≥4), and trastuzumab adjuvant regimen (sequentially vs concurrently with chemotherapy), then implemented centrally via an interactive voice and web-response system. Patients, investigators, and trial sponsors were masked to treatment allocation. The primary outcome was invasive disease-free survival, as defined in the original protocol, at 2 years after randomisation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00878709. FINDINGS: Between July 9, 2009, and Oct 24, 2011, we randomly assigned 2840 women to receive neratinib (n=1420) or placebo (n=1420). Median follow-up time was 24 months (IQR 20-25) in the neratinib group and 24 months (22-25) in the placebo group. At 2 year follow-up, 70 invasive disease-free survival events had occurred in patients in the neratinib group versus 109 events in those in the placebo group (stratified hazard ratio 0·67, 95% CI 0·50-0·91; p=0·0091). The 2-year invasive disease-free survival rate was 93·9% (95% CI 92·4-95·2) in the neratinib group and 91·6% (90·0-93·0) in the placebo group. The most common grade 3-4 adverse events in patients in the neratinib group were diarrhoea (grade 3, n=561 [40%] and grade 4, n=1 [<1%] vs grade 3, n=23 [2%] in the placebo group), vomiting (grade 3, n=47 [3%] vs n=5 [<1%]), and nausea (grade 3, n=26 [2%] vs n=2 [<1%]). QT prolongation occurred in 49 (3%) patients given neratinib and 93 (7%) patients given placebo, and decreases in left ventricular ejection fraction (≥grade 2) in 19 (1%) and 15 (1%) patients, respectively. We recorded serious adverse events in 103 (7%) patients in the neratinib group and 85 (6%) patients in the placebo group. Seven (<1%) deaths (four patients in the neratinib group and three patients in the placebo group) unrelated to disease progression occurred after study drug discontinuation. The causes of death in the neratinib group were unknown (n=2), a second primary brain tumour (n=1), and acute myeloid leukaemia (n=1), and in the placebo group were a brain haemorrhage (n=1), myocardial infarction (n=1), and gastric cancer (n=1). None of the deaths were attributed to study treatment in either group. INTERPRETATION: Neratinib for 12 months significantly improved 2-year invasive disease-free survival when given after chemotherapy and trastuzumab-based adjuvant therapy to women with HER2-positive breast cancer. Longer follow-up is needed to ensure that the improvement in breast cancer outcome is maintained. FUNDING: Wyeth, Pfizer, Puma Biotechnology.

[CROATIAN SOCIETY FOR MEDICAL ONCOLOGY CLINICAL GUIDELINES FOR DIAGNOSIS, TREATMENT AND FOLLOW-UP OF PATIENTS WITH MELANOMA]. / KLINICKE PREPORUKE HRVATSKOG DRUSTVA ZA INTERNISTICKU ONKOLOGIJU HLZ-A ZA DIJAGNOZU, LIJECENJE I PRACENJE BOLESNIKA/CA OBOLJELIH OD MELANOMA KOZE.

Melanoma in the Western world has an increasing incidence. One of the most important factor for the increase in incidence is sporadic, uncontrolled exposure to the sun. The basis for the treatment of primary melanoma is surgical treatment. Treatment of metastatic disease of melanoma in recent years experienced significant changes. BRAF and MEK inhibitors, immunotherapy with programmed cell-death immune checkpoint inhibitors (anti-PD-1-antibodies) are new options for the treatment of metastatic disease. A mulitidisiplinary team of Croatian Society for Medical Oncology provides recommendations for diagnosis, treatment and follow-up of melanoma primarily driven to the discovery of new drugs and therapeutic options, that change the prognosis of patients with metastatic melanoma.

[CANCER PATIENTS FOLLOW-UP ­ CROATIAN SOCIETY OF MEDICAL ONCOLOGY CLINICAL GUIDELINES Part I: breast cancer, uterine cancer, cervical cancer, ovarian cancer]. / PRACENJE ONKOLOSKIH BOLESNIKA ­ KLINICKE PREPORUKE HRVATSKOG DRUSTVA ZA INTERNISTICKU ONKOLOGIJU HLZ-a 1. dio: rak dojke, rak tijela maternice, rak vrata maternice, rak jajnika.

Treatment of oncological patients must be based upon multidisciplinary approach, and takes place in specialized oncological centers. By the end of a specific oncological treatment further follow-up is managed mostly by the ­oncologists, but the role of the general practitioners becomes more important every day and therefore should be precisely defined. Nowadays, most of the existing follow-up guidelines are not based on prospective studies, but on the experts ­opinion of a particular oncological center or specialists. The aim of the Croatian Society of Medical Oncology (CSMO) with these recommendations is to standardise and rationalise the diagnostic procedures algorithm in the follow-up of oncological patients after primary treatment.

CANCER PATIENTS FOLLOW-UP ­ CROATIAN SOCIETY OF MEDICAL ONCOLOGY CLINICAL GUIDELINES Part I: breast cancer, uterine cancer, cervical cancer, ovarian cancer. / PRACENJE ONKOLOSKIH BOLESNIKA ­ KLINICKE PREPORUKE HRVATSKOG DRUSTVA ZA INTERNISTICKU ONKOLOGIJU HLZ-a 1. dio: rak dojke, rak tijela maternice, rak vrata maternice, rak jajnika

Treatment of oncological patients must be based upon multidisciplinary approach, and takes place in specialized oncological centers. By the end of a specifi c oncological treatment further follow-up is managed mostly by the oncologists, but the role of the general practitioners becomes more important every day and therefore should be precisely defi ned. Nowadays, most of the existing follow-up guidelines are not based on prospective studies, but on the experts opinion of a particular oncological center or specialists. The aim of the Croatian Society of Medical Oncology (CSMO) with these recommendations is to standardise and rationalise the diagnostic procedures algorithm in the follow-up of oncological patients after primary treatment.

Real-world Outcomes of Dual HER2 Blockade Therapy in Metastatic HER2-Positive Breast Cancer: from Induction to Maintenance.

BACKGROUND AND OBJECTIVE: Dual human epidermal growth factor receptor 2 (HER2) blockade with trastuzumab and pertuzumab combined with taxane-based chemotherapy (Cht) has been the standard first-line treatment for HER2-positive metastatic breast cancer (mBC) for years, due to the impressive results of the CLEOPATRA study. Real-world (RW) studies have become critical for assessing treatment effectiveness and safety in real-life circumstances. The aim of this study was to analyze the treatment outcomes of first-line therapy for HER2-positive mBC in RW clinical practice, specifically focusing on the use of maintenance endocrine therapy (ET) in hormone receptor positive (HR-positive) patients. METHODS: This retrospective analysis included 106 HER2-positive mBC patients treated with trastuzumab and pertuzumab combined with taxane-based Cht from October 2015 to December 2020 at the University Hospital Centre Zagreb. RESULTS: At a median follow-up of 30 months, median progression-free survival (PFS) was 25 months for the total population (95% confidence interval [CI] 16 - not analyzed). Patients with de novo mBC had longer median PFS than patients with recurrent disease (not reached vs. 18 months; hazard ratio 1.99; 95% CI 0.69-3.64, p<0.022). Age, hormone receptor positivity, visceral involvement, number of Cht cycles and previous adjuvant trastuzumab did not impact PFS. Most HR-positive patients (N=55, 88.7%) received maintenance ET after induction Cht. CONCLUSION: This retrospective study provides additional data on patient characteristics, treatment and outcomes of RW HER2-positive mBC patients treated with pertuzumab and trastuzumab as first-line therapy. In our institution, maintenance ET after induction Cht has become standard clinical practice.

Salivary Interleukin-13 and Transforming Growth Factor Beta as Potential Biomarkers of Cancer Cachexia.

Cancer cachexia is a syndrome characterized by weight and muscle loss and functional impairment, strongly influencing survival in cancer patients. In this study, we aimed to establish the role of saliva cytokine measurement in cancer cachexia investigation and define two potential independent salivary biomarkers of the condition. METHODS: serum and saliva specimens were obtained from 78 patients. Forty-six patients were non-cachectic, and 32 patients were cachectic (per SCRINIO group criteria), all with metastatic solid tumors. Commercial ELISA kits were used to determine the salivary and serum concentrations of interleukin 13 (IL-13) and transforming growth factor beta (TGF-ß) in two patient groups and healthy controls. Laboratory values were obtained from the hospital information system, and weight and height were measured at the time of sampling. RESULTS: A statistically significant difference was observed between the groups in saliva IL-13 concentrations but no difference in serum concentrations. Statistically significant differences were also observed between the groups in saliva and serum concentrations of TGF-ß. Logistic regression analysis has identified salivary IL-13 and TGF-ß as independent factors for cancer cachexia. CONCLUSIONS: We demonstrated saliva as a valuable specimen for cachexia investigation and established IL-13 and TGF-ß as potential cancer cachexia biomarkers. Further research is needed to evaluate these findings.

An Unconventional Case Study of Neoadjuvant Oncolytic Virotherapy for Recurrent Breast Cancer.

Intratumoural oncolytic virotherapy may have promise as a means to debulk and downstage inoperable tumours in preparation for successful surgery. Here, we describe the unique case of a 50-year-old self-experimenting female virologist with locally recurrent muscle-invasive breast cancer who was able to proceed to simple, non-invasive tumour resection after receiving multiple intratumoural injections of research-grade virus preparations, which first included an Edmonston-Zagreb measles vaccine strain (MeV) and then a vesicular stomatitis virus Indiana strain (VSV), both prepared in her own laboratory. The intratumoural virus therapy was well tolerated. Frequent imaging studies and regular clinical observations documenting size, consistency and mobility of the injected tumour demonstrate that both the MeV- and VSV-containing parts of the protocol contributed to the overall favourable response. Two months after the start of the virus injections, the shrunken tumour was no longer invading the skin or underlying muscle and was surgically excised. The excised tumour showed strong lymphocytic infiltration, with an increase in CD20-positive B cells, CD8-positive T cells and macrophages. PD-L1 expression was detected in contrast to the baseline PD-L1-negative phenotype. The patient completed one-year trastuzumab adjuvant therapy and remains well and recurrence-free 45 months post-surgery. Although an isolated case, it encourages consideration of oncolytic virotherapy as a neoadjuvant treatment modality.

GISTs' classifications in predicting aggressive behavior: a single institution experience.

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. When making treatment plan it is very important to make proper tumor aggressiveness estimation. Traditionally, the best prognostic factors are tumor size and number of mitoses. The aim of this study was to define which GIST classification (Amin's or Newman's classification or Fletcher's Consensus Criteria) is the most significant determining prognosis and has the strongest impact on survival. This study included 63 GIST patients whose tumor specimens were evaluated by standard histopathological methods and classified based on histological assessment of malignant behavior to the three different systems. Comparison of those classification systems was done and none of them was proven to be statistically significantly better in predicting overall survival and probability of lethal outcome. We conclude that all three classifications are comparable in prediction of malignant behavior. The worst prognostic factor is existence of metastases at the time of disease diagnosis.

Optimisation of dispersive liquid-liquid microextraction for plasma sample preparation in bioanalysis of CDK4/6 inhibitors in therapeutic combinations for breast cancer treatment.

Cyclin D dependent kinase 4 and 6 (CDK 4/6) inhibitors are novel anticancer drugs used in therapeutic combinations with endocrine therapy for breast cancer treatment. Their determination in patient plasma is of high interest as a prerequisite for possible therapeutic drug monitoring. Dispersive liquid-liquid microextraction (DLLME) shows great potential in bioanalytical sample preparation. Its simplicity and speed, along with the suitability for using small amounts of sample and hazardous solvents are some of its main advantages. However, its application on plasma samples is scarce and requires further development. The aim of this work was to explore the applicability of DLLME in the simultaneous extraction of six drugs of interest from human plasma, with an emphasis placed on achieving high extraction recoveries with low sample and solvent consumption. To tackle the low availability and amount of the plasma sample, as well as the complexity of the biological matrix, three novel DLLME modes are proposed: organic sample DLLME (OrS-DLLME), aqueous sample DLLME (AqS-DLLME), and a modified air-assisted DLLME (AA-DLLME). The extractant and disperser type and volume, volume ratios of all the components in the ternary system, effect of pH and salting out were optimised for all three proposed modes of DLLME. Optimised representative DLLME-HPLC-DAD-FLD method was validated and shown to be linear (R > 0.994), precise (RSD ≤13.8%, interday), accurate (bias -13.1-13.1%, interday) and robust (relative effect -3.34-6.08%). Simultaneous extraction of all six drugs with high recoveries (81.65-95.58%) was achieved. Sample volumes used were as low as 50-100 µL, with necessary organic solvent volumes in µL ranges. Greenness scores obtained using the AGREE software were between 0.63 and 0.66, demonstrating compliance with green analytical chemistry principles. Finally, the validated method was successfully applied on breast cancer patient plasma samples.

Optimisation of Solid-Phase Extraction and LC-MS/MS Analysis of Six Breast Cancer Drugs in Patient Plasma Samples.

In the development of bioanalytical LC-MS methods for the determination of drugs in plasma samples in a clinical setting, adequate sample preparation is of utmost importance. The main goals are to achieve the selective extraction of the analytes of interest and attain thorough matrix removal while retaining acceptable ecological properties, cost-effectiveness, and high throughput. Solid-phase extraction (SPE) offers a versatile range of options, from the selection of an appropriate sorbent to the optimisation of the washing and elution conditions. In this work, the first SPE method for the simultaneous extraction of six anticancer drugs used in novel therapeutic combinations for advanced breast cancer treatment-palbociclib, ribociclib, abemaciclib, anastrozole, letrozole, and fulvestrant-was developed. The following sorbent chemistries were tested: octylsilyl (C8), octadecylsilyl (C18), hydrophilic-lipophilic balance (HLB), mixed-mode cation-exchange (MCX and X-C), and mixed-mode weak cation-exchange (WCX), with different corresponding elution solvents. The samples were analysed using LC-MS/MS, with a phenyl column (150 × 4.6 mm, 2.5 µm). The best extraction recoveries (≥92.3%) of all analytes were obtained with the C8 phase, using methanol as the elution solvent. The optimised method was validated in the clinically relevant ranges, showing adequate precision (inter-day RSD ≤ 14.3%) and accuracy (inter-day bias -12.7-13.5%). Finally, its applicability was successfully proven by the analysis of samples from breast cancer patients.

Beliefs about medicines' association with endocrine therapy adherence in early breast cancer survivors in Croatia.

This observational, cross-sectional study conducted at the University Hospital Centre Zagreb (UHC Zagreb) aimed to explore patients' beliefs about adjuvant endocrine therapy (AET) as well as their association with non-adherence and sociodemographic and clinical factors. Out of 420 early breast cancer (BC) patients included in the study, 79.5 % perceived AET necessary and important for their health, as measured by the Belief About Medicines Questionnaire (BMQ), with the mean necessity score (20.4 ± 3.68) significantly higher than the mean concerns score (13 ± 4.81) (p < 0.001). Based on the Medication Adherence Report Scale (MARS-5), 44.4 % (n = 182) of the participants were non-adherers, out of which 63.2 % (n = 115) were unintentional and 36.8 % (n = 67) intentional non-adherers. Significantly higher concern beliefs were found among patients that were younger (p < 0.001), employed (p < 0.001), intentionally non-adherent to AET (p = 0.006), had a lower body-mass index (p = 0.005) and a higher level of education (p < 0.001), were premenopausal at the time of diagnosis (p < 0.001), taking tamoxifen treatment (p = 0.05) and receiving ovarian suppression (p < 0.001). Younger patients should be recognized as being at risk of non-adherence as they hold greater concern beliefs about medicines.

Exploring adherence in patients with advanced breast cancer: focus on CDK4/6 inhibitors.

Treatment adherence is crucial for optimal outcomes in advanced breast cancer, but can be challenging due to various factors, i.e. patients' attitudes and behavior upon diagnosis, and complex therapies with high adverse effect rates. Our aim was to explore the adherence to oral anticancer medications (OAM) in women with advanced breast cancer, focusing on cyclin-dependent kinase 4 and 6 inhibitors (CDKI), and identify factors associated with the adherence. We conducted a cross-sectional study at the University Hospital Centre Zagreb, Croatia, involving women with stage IV advanced breast cancer receiving OAM. Data collection included a questionnaire assessing socio-demographic and clinical information, Beck Depression Inventory-II for depressive symptoms, Medication Adherence Report Scale (MARS-5) for adherence to OAM, and Beliefs about Medicines Questionnaire. Plasma concentrations of CDKI were confirmed by LC-MS/MS in three randomly selected participants. A total of 89 women were included. The most prescribed OAMs were anti-estrogen (71.3 %) and CDKI (60.9 %). MARS-5 scores (mean: 24.1 ± 1.6) correlated with CDKI plasma concentrations. Forgetfulness was the primary reason for non-adherence (25.9 %). Women receiving CDKI (p = 0.018), without depressive symptomatology (p = 0.043), and with more positive beliefs about medicines were more adherent (p < 0.05). This study enhances understanding of medication adherence in advanced breast cancer and identifies influential factors.