Breast cancer is the most common cancer among women worldwide, with more than 2.3 million new cases reported in 2022.1 Advances in early detection and treatment have substantially improved survival, resulting in a large and diverse population of breast cancer survivors (BCS) who face unique long-term physical, psychological, and social challenges.2 As survivorship continues to increase, care now extends beyond cancer treatment to focus on health maintenance, quality of life, and the management of late treatment-related effects.

Cardiovascular disease (CVD) has emerged as a major concern in this population. Certain cancer therapies, such as anthracyclines, HER2-targeted agents, radiation, and hormonal treatments, can cause acute or chronic cardiotoxicity, leading to left ventricular dysfunction, heart failure, or ischemic heart disease.3 The risk of cardiovascular mortality is also elevated among BCS and may not become apparent until 7 years after diagnosis.4 However, substantial gaps remain in the characterization of long-term cardiovascular risk in cancer survivors.5 These gaps highlight the need for structured surveillance strategies. Annual clinical cardiovascular risk assessments are recommended for all adult cancer survivors to optimize the management of cardiovascular risk factors, promote healthy lifestyles, and monitor symptoms.6 However, the implementation of such protocols remains limited and inconsistent7,8 and BCS are often not properly informed of their cardiovascular risk.9

Only a limited number of studies have directly assessed health care service utilization by BCS.10,11 While several studies have highlighted the need to develop cardio-oncology services for a more tailored follow-up of BCS,12,13 the actual use of cardiology services by BCS remains relatively unexplored, as most published studies are cross-sectional or have small sample sizes.7,14

Understanding patterns of health care utilization among BCS is essential to identify care gaps and improve follow-up strategies. Therefore, we aimed to describe cardiovascular comorbidities and specialized health services use, especially cardiology services, among BCS, and to examine their association with mortality.

We analyzed a large, retrospective Spanish cohort of long-term BCS, focusing on cardiovascular comorbidities and health care services utilization, especially the use of cardiology services, and their association with mortality (figure 4). This setting reflects a phase of survivorship characterized by aging and greater acquired comorbidity, and the findings should be interpreted within this specific context.

Figure 4.

Central illustration. Cardiovascular comorbidity, cardiology care, and mortality among long-term breast cancer survivors. Retrospective cohort of 6186 Spanish breast cancer survivors (diagnosed 2000-2006; ≥ 5-year survival) followed up from 2012 to 2016. Panel 1: cohort overview. Panel 2: nonsurvivors (12.6%) were older, had higher comorbidity, more severe cardiovascular disease, and more intense health care use. Panel 3: Covariate-adjusted survival probabilities derived from the time-dependent Cox model. These curves should be interpreted as model-based standardized survival functions under fixed exposure regimes, rather than observed survival trajectories. aHR, adjusted hazard ratio; BCS, breast cancer survivors.

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The prevalence of CVD in our BCS cohort (43%), which included only women surviving at least 5 years after diagnosis, was higher than that in studies including 1-year survivors,17 likely reflecting older age and longer follow-up. However, it was lower than hypertension rates reported at diagnosis in other cohorts.18 These differences may reflect varying follow-up durations, measurement timing, and survivor bias, as early events or more severe disease may be underrepresented in long-term survivors.19 Furthermore, women with baseline CVD were older and had a higher comorbidity burden than those without baseline CVD, suggesting that CVD in this population occurs within a broader context of multimorbidity, likely influenced by older age.20

Although the overall health care use among BCS has been described previously,10 evidence is scarce on specialist or cardiology utilization and its impact on outcomes.14 We extend these findings by characterizing longitudinal patterns of specialist care.

Nonsurvivors showed more intensive health care use but consulted fewer distinct specialists, consistent with evidence of increasing service concentration near the end of life, regardless of the cause of death.21 In particular, the concentration of visits in cancer management-related services may reflect cancer recurrence and a cancer-related cause of death. These patterns are consistent with time-dependent health care utilization as measures capturing underlying disease severity, which explains their positive association with mortality in adjusted analyses. Furthermore, these patterns and are in line with prior studies reporting greater end-of-life healthcare use among individuals dying of cancer.22,23

Many BCS, including those with baseline CVD, and particularly those who died during follow-up, did not access cardiology services. Importantly, cardiovascular care in this population is not exclusively delivered by cardiologists and may be provided by primary care or other specialties. Nevertheless, this mismatch between need and specialized care delivery may arise from limitations in the referral system or patient-related barriers.24,25 Notably, the subgroup of nonsurvivors who had CVD and did not use cardiology services had the highest mean age and the greatest comorbidity burden at baseline. These patients also consulted the lowest number of different specialists. This finding highlights the need for tailored strategies to ensure adequate cardiology follow-up, especially in BCS with a higher CVD comorbidity burden, as seen here and in earlier studies,26 and who might face additional barriers such as frailty, mobility limitations, or competing health priorities.27 Previous studies have reported less intensive health care use at the end of life among older patients compared with younger nonsurvivors, regardless of the cause of death.21 There have also been reports of the increased challenges encountered by older adults, especially women, in accessing health care, influenced by health, socioeconomic, and contextual factors.28

Several studies have reported higher cardiovascular mortality among BCS.29,30 In our study, although cause of death was not available, crude mortality was slightly higher among survivors with baseline CVD, and nonsurvivors had a higher prevalence of CVD, particularly severe conditions such as arrhythmia, cerebrovascular disease, heart failure, and ischemic heart disease.30–32

Among women with baseline CVD, cardiology utilization was associated with lower mortality. After adjustment for age, baseline and the cumulative number of comorbidities, and health care use intensity, cardiology use remained associated with a lower hazard of all-cause mortality, although this association did not reach statistical significance. These findings are consistent with current onco-cardiology recommendations emphasizing structured, risk-adapted cardiovascular follow-up and clinically indicated cardiology referral in long-term cancer survivors.6

Differences in cardiology services use over time between survivors and nonsurvivors at the end of follow-up were observed. Nonsurvivors consistently showed more intense cardiology use throughout follow-up, without a decline near the end of life. Conversely, the reduced cardiology use observed among survivors toward the end of follow-up may reflect a general decline in long-term surveillance among those with fewer comorbidities, as previously reported,33 potentially reflecting a natural tendency to disengage from care as the perceived health threat diminishes. The inverse association with comorbidity burden may reflect more medical visits and closer follow-up, which may explain the apparent protective effect of higher baseline comorbidities.

The main strengths of this study include its large, population-based national cohort with real-world health care data, enabling detailed assessment of health care use among BCS. Its longitudinal design allowed the evaluation of long-term patterns and outcomes across specialties, highlighting gaps in cardiology care and opportunities for integrated cardio-oncology management. Modeling cardiology use and the cumulative number of comorbidities as time-dependent covariates provides a more accurate representation of patients’ evolving clinical status, although it may reduce statistical power. As with any study using administrative health care data, our analysis may be affected by incomplete or inaccurate visit codes and dates, as well as missing or outdated patient information. Cause of death data were unavailable, limiting the ability to directly link outcomes to cardiovascular or cancer-related events. Accordingly, findings should be interpreted in terms of all-cause mortality only. Data on molecular cancer type and treatments were not available, preventing assessment of treatment effects on cardiology follow-up and outcomes, as well as treatment-related heterogeneity. Furthermore, other unmeasured factors related to disease severity or health care-seeking behaviors may have influenced the observed associations. In particular, patients referred to cardiology are likely to differ systematically from those who are not, as referral decisions are influenced by the physician's assessment of cardiovascular risk and clinical need, which can only be partially addressed by our adjustment strategy. Finally, the follow-up extended only until 2016, when cardio-oncology practices in Spain were still emerging and were not widely implemented, which should be considered when extrapolating these findings to current clinical practice.34

The prevalence of CVD among BCS was high, although only 18.8% used cardiology services. Comorbidity, overall health care utilization, and cardiology service use in particular were higher in women with baseline CVD. Nonsurvivors had a higher baseline CVD burden, more severe cardiovascular conditions, and made greater use of health care services. The use of cardiology services was not statistically significantly associated with lower mortality.

This work was supported by PI22/00020 and PI19/00056 funded by the Instituto de Salud Carlos III (ISCIII) and cofunded by the European Union; and RD24/0005/0002, and RD21/0016/0020 funded by Instituto de Salud Carlos III (ISCIII), and by the European Union NextGenerationEU, Mecanismo para la Recuperación y la Resiliencia (MRR).

The study was performed in accordance with the Declaration of Helsinki of the World Medical Association and approved by the Parc de Salut Mar Research Ethics Committee (CEIM PSMAR 2019/8639/I). This was a retrospective study using anonymized data; therefore, the need for written informed consent was waived by the Ethics Committee. The SAGER guidelines were not applicable to this study, as the population exclusively consisted of women and no sex/gender comparisons were performed.

During the preparation of this work, the authors used ChatGPT for minor language refinement in limited portions of the text. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

M. Botello-Marabotto performed data analysis and drafted the manuscript. M. Comas helped with the relevant statistical tests and with interpreting the results. D. Abbad-Gómez, L. Domingo, B. Ibañez-Beroiz, I. Tamayo, B. Poblador-Plou, A. Gimeno-Miguel, M. Redondo, M. Padilla, I. del Cura, T. Sanz, A. Díaz-Holgado, H. Tizón-Marcos, and X. Castells revised the manuscript and provided feedback on epidemiological and statistical issues. M. Sala supervised the work, helped with interpreting the results, and revised and approved the final manuscript.

H. Tizón-Marcos reports a public institutional leadership role as Director of the Pla Director de Malalties Cardiovasculars (Generalitat de Catalunya), outside the submitted work. The remaining authors declare no conflicts of interest.