Breast cancer remains one of the most significant challenges in oncology and is the fourth most common cause of cancer-related deaths overall, ranking first among causes of cancer mortality in women (1). In Poland, it is the third most frequently diagnosed cancer, with 24, 418 new cases reported in 2022, accounting for 11.7% of all cancer diagnoses nationwide. The disease contributes substantially to cancer mortality and prevalence, with 8, 723 deaths (7.3% of all cancer-related deaths) and a five-year prevalence of 100, 017 cases, reflecting a large and growing population of women living with breast cancer or its sequalae (2).

Although breast cancer is increasingly recognized as a chronic disease, survival rates in Poland remain lower than the European average, despite significant global improvements over recent decades resulting from advances in early detection, treatment strategies, and public awareness. Since the mid-2000s, several initiatives have been undertaken in Poland to improve cancer care outcomes. These include two editions of the National Program for Cancer Disease Control. A key policy milestone occurred in January 2015, when a dedicated “fast-track” oncology pathway was introduced to expedite diagnosis and treatment for patients suspected of having cancer. In 2019, the National Oncology Network (NON) was piloted and now constitutes a central component of the National Cancer Strategy for 2020–2030 (3). A deeper understanding of the biological profiles of breast cancer within the Polish population is essential, as these features guide precision medicine approaches and provide prognostic and predictive value regarding treatment response, recurrence risk, metastatic patterns, and overall outcomes.

This article, for the first time, explores the breast cancer survival - encompassing tumor biology and patient characteristics—in women newly diagnosed between 2019 and 2023 in the Lower Silesia region, as part of the pilot implementation of the National Oncology Network.

This study is a retrospective data analysis based on a cohort derived from the pilot implementation of the National Oncology Network (NON) in the Lower Silesia region, coordinated by the Lower Silesian Oncology Center (DCOPiH), covering the period from February 1, 2019, to March 31, 2023. Data were collected by the National Health Fund in cooperation with healthcare providers based on the respective ACT (4) and the MoH Regulations. The security and protection of data was assured. A total of 6, 917 female patients newly diagnosed with primary breast cancer were included. Data collection occurred in multiple stages. In the initial phase, patients who provided informed consent (in NON pilot) and had histopathologically confirmed diagnoses were enrolled. This retrospective cohort study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines.

Eligible participants were adult women (aged ≥18 years) with newly diagnosed primary breast cancer diagnosis (stage 0-IV) between from February 1, 2019, to March 31, 2023, regardless of treatment intent. Clinical data were extracted from medical records and coded according to the International Classification of Diseases for Oncology, Third Edition (ICD-O-3) (5), including invasive carcinoma (code C50) and in situ lesions (code D05). All patients included in the National Cancer Network (NCN) pilot program in Poland made a written declaration of informed consent to participate in the NCN pilot program (6). Before enrollment, each patient obtained information about the principles of the pilot program and the detailed information of personal data processing as part of the NCN (6) and the long effectiveness evaluation. Tumor staging was classified into five categories (0, I, II, III, and IV), and TNM staging was determined based on the AICC/UICC and the ESMO Clinical Practice Guidelines (7). Deaths from any cause were analyzed and survival curves were generated for the entire cohort, stratified by clinical stage and biological subtype, including luminal A, luminal B, HER2-positive, and triple-negative breast cancer.

Nominal variables were summarized using frequencies and percentages, while interval-scaled variables were described using the mean, standard deviation, median, range, and interquartile range (IQR). A statistical significance level of 0.05 was adopted for the analysis. Survival analysis was conducted using the Kaplan–Meier method for the entire cohort, as well as stratified by biological subtype, clinical stage, stage within subtype, and screening status. A complete-case approach was applied, in which follow-up time was calculated from the date of diagnosis to either the date of death or the end of the study period. Differences in survival between subgroups were assessed using the Cox proportional hazards model.

Five-year (60-month) overall survival was estimated using the Kaplan–Meier product-limit method. Because the diagnostic period (2019–2023) includes patients without the possibility of complete 5-year follow-up (e.g., those diagnosed in 2022–2023), the 60-month survival probability represents a Kaplan–Meier estimate at t = 60 months, i.e., an estimate obtained under right censoring rather than observed 5-year follow-up for all individuals. Patients contributed risk time from diagnosis until death or administrative censoring; those without an event by the censoring date were treated as right-censored.

Follow-up time was defined as the time from diagnosis to removal from the risk set (death or censoring). In the analytical cohort, follow-up ranged from 7 to 2, 269 days (median 1, 313 days, IQR 935–1, 723). Among censored individuals, time to censoring ranged from 35 to 2, 269 days (median 1, 388 days, IQR 1, 044–1, 790). Thus, the minimum potential follow-up in the dataset was 7 days (overall) and 35 days among those censored.

This study provides comprehensive population-based insights into breast cancer survival in the Lower Silesia region during the pilot phase of the National Oncology Network (NON), with a specific focus on the prognostic relevance of clinical stage and biological subtype. The results confirm that disease stage at diagnosis remains the strongest determinant of patient outcomes, regardless of tumour biology. These findings align with international evidence and underscore the critical need for early detection, structured care coordination, and standardized reporting.

The share of categories 0+I (combined) fluctuated between 37.2% and 41.7% across the years with the share of stage I within a range of 34.5% to 41.2%. The lowest proportion was recorded in 2022 (37.2%) due to COVID19 pandemia impact, while the highest was in 2023 (41.7%). Overall, the average for the five-year period stands at 39.6%, showing a relatively stable but slightly increasing trend toward the end of the observed period. In contrast, the share of categories III+IV (combined) remained fairly stable, ranging between 27.3% and 29.9%. The highest proportions were observed in 2020 and 2022 (29.9%), whereas the lowest appeared in 2023 (27.3%). The five-year average is 28.9%, with no clear upward or downward trend overall. During the pandemic, from March 2020 to May 2022, the number of tests statistically decreased dramatically to an average of 37.93 per month for overall newly diagnosed breast cancer in DCOPIH, while positive diagnoses dropped to 24.74 per month. In comparison, from January 2018 to February 2020, the number of histopathological tests for breast cancer was relatively stable, averaging 67.23 per month, with 31.50 positive diagnoses (with positive diagnoses during this period was 46.85%) (8).

Consistent with previous studies, patients with the luminal A subtype exhibited the most favourable prognosis, with 60-month survival rates exceeding 90% in total population and 95% in stages 0 and I. This outcome reflects the relatively indolent clinical course and strong responsiveness to endocrine therapy characteristic of this subtype (9, 10). Luminal B tumours, although also hormone receptor–positive, were associated with a moderately worse prognosis—especially at advanced stages—likely due to higher proliferation indices and reduced endocrine sensitivity (11). Among HER2-positive patients, survival was high in early stages but declined at stage IV (54.6%), probably due the availability of targeted therapies such as trastuzumab and pertuzumab (12, 13). Triple-negative breast cancer (TNBC) was associated with the poorest prognosis, showing a precipitous drop in 60-month survival from 86.0-87.5% at stages 0 and I to only 63.8% at stage III. In stage IV TNBC cancer no patient was observed to achieve a 48-month survival and the study documented a 36-month survival rate of only 6.1% (14, 15). The fact that this particular type of cancer has such a low survival rate is especially notable given that this specific subtype comprised the highest proportion of patients in the youngest age group, i.e. those under 30 years of age.

The pattens of age structure within each biological subtype in our study reflect the known association between tumour biology and patient age, with hormone receptor–positive subtypes being more common in older women, and aggressive subtypes such as TNBC and HER2-positive tumours being relatively more prevalent among younger patients within their respective subtype distributions. Age at diagnosis may then inform risk stratification, surveillance intensity, and treatment planning.

Importantly, while biological subtype stratifies risk within stages, survival declined consistently across all subtypes with increasing disease stage. Patients with stage 0 and I disease had 60-month survival rates exceeding 86%, while those diagnosed at stage IV had survival rates as low as 0–54.6%, depending on subtype. Notably TNBC cases showed the most pronounced stage-dependent decline. These findings reflect the biological aggressiveness and limited treatment options for TNBC and reinforce the need for intensified systemic therapy and rapid intervention in this group.

Despite significant improvements in breast cancer treatment, Poland continues to lag behind many EU countries in survival outcomes. In 2021, breast cancer mortality in Poland was 20 per 100, 000 women - 5% higher than the EU average. While the mortality rate declined by 8% in Poland between 2011 and 2021, the EU average saw a 16% reduction during the same period. Moreover, while two-thirds of EU countries had reached five-year survival rates of ~80% for breast cancer patients diagnosed between 2000 and 2007, Poland only achieved a similar benchmark for patients diagnosed between 2015 and 2018 (16). For this period, five-year survival in Poland was 77%, compared to the EU average of 82%. Regional disparities further complicate the landscape: five-year survival in the 2010–2014 period ranged from 69.7% (Podkarpackie) to 79.8% (Mazowieckie), with Lower Silesia at 77.3%—broadly consistent with our observed outcomes.

The pilot implementation of the National Oncology Network in Lower Silesia aimed to address these systemic deficiencies. It introduced standardized diagnostic and treatment pathways, mandatory participation of multi-level care providers (SOLO I–III), and centralized coordination by Provincial Coordinating Centers. Additionally, it was the first nationwide program to implement real-time digital data collection and reporting for oncology quality indicators. The Lower Silesia Oncology Center was also the first in Poland to obtain iPAAC certification in breast cancer care, contributing to consistent and standardized data collection.

Nevertheless, the results reveal persistent gaps in early detection. Only 2.7% of patients in this population were diagnosed at stage 0, but European guidelines recommending that at least 15% of new breast cancer cases should be diagnosed at this stage in this population (17). In the pilot population for the Lower Silesia 7.3% had in situ breast cancer. Furthermore, only 36.0% of cases were detected at stage I, while stages III and IV accounted for 21.9% and 7.0%, respectively. These distributions stand in contrast to results from Norway (2005–2010), where 90.6% of cancers were diagnosed at stages I–II, and just 9.4% at stages III–IV, as well as similar benchmarks in the Netherlands and Spain (18).

These observations are particularly concerning given that participation in screening programs in Poland remains low - only 37% of eligible women underwent screening in 2023. In our analysis, patients aged 50–69 who participated in screening at DCOPiH had 36 and 60-month survival rates of 94.8% and 89.5 respectively, compared to 90.9% and 86.3% among non-participants. Although the difference did not reach conventional statistical significance (HR = 0.66 CI 0.42-1.02 p = 0.059), it reflects a clinically relevant benefit and aligns with previous European data showing that population-based screening programs reduce the incidence of advanced breast cancer and improve survival (19–24).

Indeed, systematic reviews and cohort studies from the Netherlands, Sweden, Finland, Italy, Germany, and France have consistently demonstrated that organized screening programs lead to a measurable reduction in the incidence of advanced-stage disease (T2+, N+, stage II+) (25). For example, Paci et al. (26) reported a risk ratio of 0.72 for stage II+ cancers in screened versus unscreened populations, while Dutch studies (27) showed annual reductions in advanced breast cancer incidence ratios ranging from 0.86 to 0.72 (19, 21). Our findings are consistent with these trends and reinforce the need for broader access and adherence to screening programs in Poland. Finally, while our results generally correspond to international registry data (e.g., Canadian Cancer Registry), notable differences remain in the distribution of disease stages and biological subtypes. For example, Canadian data showed about 47% of luminal A tumours, whereas this figure was 30.3% in our cohort (28). These discrepancies may reflect differences in population structure, access to care, and data completeness.

Survival outcomes in breast cancer in Poland are strongly influenced by both the biological subtype and the stage at diagnosis. Early-stage detection through screening and rapid diagnostic pathways remain the most effective strategies to improve prognosis, particularly for aggressive subtypes such as TNBC and HER2-positive disease. The implementation of the National Oncology Network represents a step toward coordinated, data-driven cancer care in Poland, but further efforts are needed to increase screening participation, reduce diagnostic delays, and standardize treatment across regions.