Abstract
Background
General practitioners (GPs) play an increasingly central role in the detection and management of breast cancer recurrence (BCR). Socioeconomic position (SEP) has been associated with both risk of BCR and mortality and may influence cancer awareness and beliefs, healthcare-seeking behaviour, referral patterns, and access to and use of healthcare. Nevertheless, knowledge on how SEP is related to BCR detection in general practice remains limited.
Aim
To characterise patients with BCR and examine how SEP is associated with involvement of general practice in the pathway to recurrence diagnosis (index consultation), symptom presentation in general practice, and the GP’s decision to initiate a diagnostic pathway.
Methods
In this nationwide retrospective cohort study, national register data on women diagnosed with BCR between 1 January 2022 and 31 May 2024 were combined with GP survey data from 324 Danish GPs. SEP was measured as educational level and cohabitation status. Associations with study outcomes were analysed by estimating prevalence ratios using Poisson regression models.
Results
Among 392 women with BCR, 52.8% had an index consultation in general practice, 37.2% presented with symptoms in general practice, and 43.6% had the diagnostic pathway initiated by the GP. Across all analyses, no statistically significant associations were found between SEP and the investigated outcomes.
Conclusion
The findings suggest no substantial socioeconomic disparities in the likelihood of having an index consultation in general practice, presenting with symptoms in general practice, or having the diagnostic pathway initiated by the GP when presenting with symptoms.
Keywords: Denmark, general practice, socioeconomic factors, breast neoplasms, recurrence, surveys and questionnaires, cohort studies
Introduction
In recent decades, advances in early detection and treatment have improved breast cancer (BC) survival [1]. Due to increasing incidence and 5-year survival rates exceeding 90% in high-income countries, the prevalence of BC continues to rise [2]. In 2024, the Danish 10-year prevalence of BC was more than 2% among women aged 40 years or more [3].
While the responsibility for surveillance of breast cancer recurrence (BCR) has traditionally been placed in the context of hospital-based follow-up care, recurrence is frequently detected outside these planned visits on the basis of signs or symptoms [4–7]. This underscores the central role of general practice in survivorship care [8,9].
BCR may be identified through several pathways involving both primary care and secondary care, including presentation in general practice, hospital-based follow-up care, mammography screening, direct patient contact with the hospital services, private specialist consultations, out-of-hours-services, or during hospitalisation [6,10,11]. In Denmark, hospital-based follow-up after primary BC diagnosis is organised according to national guidelines, and focus on management of physical and psychosocial late effects and detection of recurrence [10,11]. Follow-up programmes are predominantly needs-based and emphasise easy access to clinical assessment and diagnostic workup in case of relevant symptoms or signs of recurrence. Follow-up in specialised care is recommended until side-effects from primary treatment have stabilised, while all patients are advised to participate in mammography screening until age 80 years, with follow-up every 1–2 years depending on age. Apart from mammography, routine radiological or biochemical examinations are only performed in patients with clinical suspicion of BCR [10]. The Danish College of General Practitioners has published a guideline on cancer survivorship [12]. General practitioners (GPs) contribute to continuity and accessibility in survivorship care and refer patients with suspected recurrence to a diagnostic cancer patient pathway (not recurrence-specific) [11] or to a relevant hospital department [12].
Unlike other cancer types, the risk of BCR remains increased for many years after treatment of the primary cancer [13,14]. Factors associated with BCR include patient age, adjuvant treatments, characteristics of the primary tumour [14–17], and socioeconomic position (SEP) [14]. SEP is multidimensional, and no single indicator captures all of its aspects, as different SEP indicators may reflect different, although related, dimensions of SEP [18,19]. Educational level and cohabitation status may represent complementary indicators of socioeconomic inequalities. Educational level may reflect knowledge- and resource-related socioeconomic factors [18,19], whereas cohabitation status may reflect social and partner support relevant to health behaviour and health outcomes [19,20]. Lower SEP has been associated with a higher risk of recurrence and poorer BC mortality outcomes [14,21–24]. Delayed diagnosis due to lower mammography screening participation rates [25,26], influence of cancer awareness [27], barriers to healthcare-seeking, and negative beliefs about cancer [28] may contribute to these differences. Furthermore, socioeconomic factors have been suggested to influence GPs’ referral patterns to private specialists and hospitals [29]. Additionally, international research suggests that socioeconomic inequalities in access to and use of care differ between primary and specialist care in the general population [8,30]. In Danish cancer survivors, short education has been associated with more GP consultations and fewer private practising specialist consultations, while no differences were seen in the number of hospital contacts [31]. However, evidence on the potential influence of SEP on the pathway to BC recurrence diagnosis remains limited, and an enhanced understanding is needed.
The aim of this study was to characterise patients with BCR and to examine how SEP is associated with general practice involvement in the pathway to recurrence diagnosis (index consultation), symptomatic versus asymptomatic presentation in general practice, and the GP’s decision to initiate a diagnostic pathway.
Methods
Study design and setting
The data originated from a nationwide retrospective cohort study [6] that combined register data on women with BCR and survey data from GPs. In Denmark, all citizens have access to publicly funded healthcare. More than 98% of the population are registered with a general practice, which they must consult for medical advice. As gatekeepers to specialised healthcare services, GPs may refer patients to hospitals. Medical records are kept by the GP, including test results and hospital discharge letters [32].
Study population
We identified female patients with a primary BC (diagnosis code C50 in the International Classification of Diseases, 10th revision (ICD-10)) [33], diagnosed between 2012 and 2024, with no other cancer diagnoses, using data from the Danish Cancer Registry (DCR) [33]. The most recent BC diagnoses were identified through the Danish National Patient Register (DNPR) [34]. Patients identified with BCR were eligible for inclusion. A validated register-based algorithm using pathology records and procedure- and diagnosis codes as indicators of BCR was used to identify patients diagnosed with BCR between 1 January 2022 and 31 May 2024 [35]. See Supplementary material, Table S1, for an overview of the data sources and information obtained from each source.
Indicators and definition of BCR
Indicators of BCR were based on pathology test results from the Danish National Pathology Register [36] and BCR-related procedure and diagnosis codes from the DNPR [34]. BCR was defined as the return of cancer at the original site or a distant location after curative treatment and a subsequent period with no register-based evidence of ongoing disease to indicate remission [6]. Based on the most recent event, this period was defined as 30 days after the end of adjuvant therapy or 90 days after surgery [35].
Data collection
Information on the registered general practice for each included patient was obtained from the Danish National Health Service Register [37]. Eligible GPs were invited to complete a questionnaire regarding the diagnostic pathway between January 2023 and July 2024. The first invitations were sent for patients diagnosed with BCR within the first 12 months and thereafter every four months, followed by a reminder to non-respondents after three weeks. Participation was remunerated with DKK 146 (EUR 20).
Questionnaire variables
The questionnaire included items regarding the specific patient with BCR and covered (1) whether the patient presented symptoms or signs of illness in general practice in the months leading up to the recurrence diagnosis, (2) the place of diagnostic initiation, and (3) whether the patient was enrolled in specialised follow-up at the time of BCR diagnosis. The GP response rate was 51.3% (Figure 1). An English translation of the questionnaire items is provided in the Supplementary material, Table S2.
Figure 1.
Flowchart of the study population. Abbreviations: BCR: breast cancer recurrence; n: number.
To assess general practice involvement in the pathway to recurrence diagnosis, an index consultation was defined as (1) presentation of symptoms in general practice and/or (2) general practice as the place of diagnostic initiation, thereby also capturing asymptomatic presentations. An asymptomatic presentation was defined as patients who had not presented symptoms in general practice, but general practice was ticked as the place of diagnostic initiation. Based on symptom presentation and place of diagnostic initiation, patients with an index consultation were categorised into different diagnostic pathways: 1) symptomatic presentation in general practice and diagnostics initiated by the GP, 2) symptomatic presentation in general practice and diagnostics initiated outside general practice, and 3) asymptomatic presentation in general practice and diagnostics initiated by the GP.
Study variables
The study outcome variables were: (1) an index consultation in general practice (yes/no), (2) symptom presentation in general practice (yes/no), and (3) GP initiation of the diagnostic pathway among symptomatic patients (yes/no).
SEP was based on educational level and cohabitation status obtained from Statistics Denmark [38] at the time of BCR diagnosis. Educational level was categorised according to the International Standard Classification of Education (ISCED) [39] by number of years of education:’ short’ (<10 years),’ medium’ (10–15 years), and’ high’ (>15 years). Cohabitation status was divided into two categories:’ living alone’ (unmarried, divorced, or widowed) and’ cohabitating’ (married or registered as living with a partner).
Physical comorbidity was assessed using the Charlson Comorbidity Index (CCI) [40]. CCI scores were based on diagnosis codes (excluding cancer-related diagnoses) in the DNPR [34] for hospital contacts during the 10 years prior to BCR diagnosis. Patients were categorised into’ low’ (score 0),’ moderate’, (scores 1–2), and’ severe’ (scores >2). Age was obtained at the time of BCR diagnosis and categorised into four groups:’ 18–54’,’ 55–64’,’ 65–74’, and’ >74’ years. Time from the primary BC diagnosis was modelled as a continuous variable, defined as the number of years between the date of primary BC (obtained from the DCR [33] and the DNPR [34]) and the date of BCR diagnosis, as identified by the algorithm.
Statistical analysis
All analyses were performed on the server of Statistics Denmark. Frequencies and percentages were used to summarise study variables. Associations between SEP and outcome variables were assessed by estimating crude and adjusted prevalence ratios (PRs) with 95% confidence intervals (CIs) using generalised linear models for the Poisson family with logarithmic link and robust variance estimation (binary outcome). Due to a small number of events, the analysis of symptomatic presentation in general practice was adjusted only for age and the other SEP indicator, and the analysis of GP-initiated diagnostic procedures was adjusted only for age. Age was categorised based on clinical relevance and to allow for potential non-linear associations between age and the outcomes. Sensitivity analysis modeling age as a continuous variable using restricted cubic splines yielded similar results, thereby supporting the robustness of the findings.
Data analysis was conducted in Stata®, version 18.0.
Results
From 911 patients identified with BCR, a total of 392 patients from 324 general practices were included in the study as the GP provided complete questionnaire information and verified the BCR diagnosis (Figure 1). Characteristics of the study population are presented in Table 1. Most patients were aged 65–74 years. Most patients had a medium educational level, and about half were cohabitating. Median time since primary diagnosis was 5.3 years, and 58% of patients were enrolled in specialised follow-up.
Table 1.
Characteristics of the study population of patients with incident breast cancer recurrence (January 2022 to May 2024) as identified by the algorithm (n = 392).
| Study population n (%) | |
|---|---|
| Total | 392 (100.0) |
| Age group (years) | |
| 18–54 | 86 (21.9) |
| 55–64 | 82 (20.9) |
| 65–74 | 116 (29.6) |
| >74 | 108 (27.6) |
| Educational level a | |
| Short | 101 (25.8) |
| Medium | 154 (39.3) |
| High | 137 (35.0) |
| Cohabitation status b | |
| Living alone | 182 (46.4) |
| Cohabitating | 210 (53.6) |
| Comorbidity level c | |
| Low | 306 (78.1) |
| Moderate | 75 (19.1) |
| Severe | 11 (2.8) |
| Time since primary cancerd (years), median [IQI] | 5.3 [2.9–8.4] |
| Follow-up status | |
| Active follow-up | 227 (57.9) |
| Completed follow-up | 150 (38.3) |
| Unknown | 15 (3.8) |
| Diagnostic pathway | |
| Index consultatione in general practice | |
| Symptomatic presentation to GP and diagnostics by GP | 110 (28.1) |
| Symptomatic presentation to GP and diagnostics by non-GP | 36 (9.2) |
| Asymptomatic presentation to GP and diagnostics by GP | 56 (14.3) |
| Diagnostics by GP and unknown status of symptom presentation | 5 (1.3) |
| No index consultation in general practice | |
| No consultation with GP or asymptomatic presentation to GP and diagnostics by non-GP | 169 (43.1) |
| Unknown status of index consultation in general practice | |
| Diagnostics by non-GP and unknown status of symptom presentation | 16 (4.1) |
Abbreviations: GP: general practitioner; IQI: interquartile interval.
aFollowing the International Standard Classification of Education (ISCED) [39], divided into categories based on years of education:’ short’ (<10 years),’ medium’ (10–15 years), and’ high’ (>15 years).
bDivided into: ‘living alone’ (unmarried, divorced, or widowed) and ‘cohabitating’ (married or registered as living with a partner).
cFollowing the Charlson Comorbidity Index (CCI) [40], divided into CCI scores: ‘low’ (score 0), ‘moderate’ (scores 1–2), and ‘severe’ (scores >2). CCI scores are based on diagnosis codes, excluding cancer diagnosis, from the Danish National Patient Register (DNPR) [34] in the 10 years prior to a recurrence diagnosis.
dDefined as the number of years between primary breast cancer diagnosis and date of recurrence diagnosis. Data from the Danish Cancer Registry (DCR) [33] and the Danish National Patient Register (DNPR) [34].
eDefined as (1) symptom presentation in general practice and/or (2) general practice as place of diagnostic initiation.
Diagnostic pathways
Of all patients, 207 (52.8%) had an index consultation in general practice, 146 (37.2%) presented with symptoms in general practice, and 171 (43.6%) had their diagnostic pathway initiated by the GP. Among those who presented symptoms, 110 (75.3%) had their diagnostic pathway initiated by the GP (Table 1).
SEP and index consultation in general practice
No statistically significant associations were observed between SEP and having an index consultation in general practice. The point estimate comparing patients with a high educational level with those with a short educational level was above 1 (PR 1.13 95%CI 0.88–1.45) (Table 2).
Table 2.
Prevalence ratios of having an index consultationa in general practice among patients with incident breast cancer recurrence.
| n | Unadjusted (PR 95%CI) |
Adjustedb (PR 95%CI) | |
|---|---|---|---|
| Educational level c | |||
| Short | 100 | 1 (reference) | 1 (reference) |
| Medium | 146 | 1.04 (0.82–1.32) | 1.02 (0.80–1.29) |
| High | 130 | 1.12 (0.89–1.43) | 1.13 (0.88–1.45) |
| Cohabitation status d | |||
| Living alone | 177 | 1 (reference) | 1 (reference) |
| Cohabitating | 199 | 0.95 (0.79–1.14) | 1.03 (0.85–1.25) |
Patients with unknown status of index consultation were excluded (n = 16) (n = 376).
Abbreviations: CI: confidence interval; PR: prevalence ratio.
aDefined as (1) symptom presentation in general practice and/or (2) general practice as the place of diagnostic initiation.
bAdjusted for educational level, cohabitation status, age, comorbidity, time since primary diagnosis, and follow-up status.
cFollowing the International Standard Classification of Education (ISCED) [39], divided into categories based on years of education:’ short’ (<10 years),’ medium’ (10–15 years), and’ high’ (>15 years).
dDivided into: ‘living alone’ (unmarried, divorced, or widowed) and ‘cohabitating’ (married or registered as living with a partner).
SEP and symptom presentation in general practice
Among patients with an index consultation in general practice, no statistically significant associations were observed between SEP and symptom presentation in general practice. Specifically among patients whose diagnostic pathway was initiated in general practice, no statistically significant associations between SEP and symptom presentation were observed. In both analyses, the point estimates among patients with a high educational level were below 1 (PR 0.86, 95%CI 0.68–1.08 and PR 0.80, 95%CI 0.59–1.09, respectively), and the point estimates among cohabitating patients were above 1 (PR 1.06, 95%CI 0.88–1.27 and PR 1.11, 95%CI 0.88–1.39, respectively) (Table 3).
Table 3.
Prevalence ratios of symptomatic versus asymptomatic presentation in general practice.
|
Among patients with an index consultationa
in general practice (n = 202) |
Among patients with initiation of the diagnostic pathway in general practice (n = 166)
|
|||||
|---|---|---|---|---|---|---|
| N | Unadjusted (PR 95%CI) | Adjustedb (PR 95%CIb) | n | Unadjusted (PR 95%CI) | Adjustedb (PR 95%CI) | |
| Educational level c | ||||||
| Short | 51 | 1 (reference) | 1 (reference) | 42 | 1 (reference) | 1 (reference) |
| Medium | 76 | 0.98 (0.80–1.20) | 0.98 (0.80–1.20) | 66 | 1.00 (0.78–1.27) | 1.00 (0.78–1.29) |
| High | 75 | 0.87 (0.70–1.09) | 0.86 (0.68–1.08) | 58 | 0.80 (0.59–1.07) | 0.80 (0.59–1.09) |
| Cohabitation status d | ||||||
| Living alone | 98 | 1 (reference) | 1 (reference) | 78 | 1 (reference) | 1 (reference) |
| Cohabitating | 104 | 1.02 (0.86–1.21) | 1.06 (0.88–1.27) | 88 | 1.06 (0.85–1.32) | 1.11 (0.88–1.39) |
Abbreviations: CI: confidence interval; PR: prevalence ratio.
aDefined as (1) symptom presentation in general practice and/or (2) general practice as the place of diagnostic initiation.
bAdjusted for educational level, cohabitation status, and age.
cFollowing the International Standard Classification of Education (ISCED) [39], divided into categories based on years of education:’ short’ (<10 years),’ medium’ (10–15 years), and’ high’ (>15 years).
dDivided into: ‘living alone’ (unmarried, divorced, or widowed) and ‘cohabitating’ (married or registered as living with a partner).
SEP and diagnostic initiation in general practice
No statistically significant associations between SEP and initiation of the diagnostic pathway by the GP were observed among patients who presented with symptoms in general practice. The point estimates were lower among patients with a high educational level (PR 0.89, 95%CI 0.68–1.15) and higher among cohabitating patients (PR 1.13, 95%CI 0.93–1.37) (Table 4).
Table 4.
Prevalence ratios of initiation of the diagnostic pathway in general practice among patients with symptomatic presentation in general practice (n = 146).
| n | Unadjusted (PR 95% CI) | Adjusteda (PR 95%CI) | |
|---|---|---|---|
| Educational level b | |||
| Short | 39 | 1 (reference) | 1 (reference) |
| Medium | 57 | 1.07 (0.87–1.32) | 1.08 (0.87–1.35) |
| High | 50 | 0.86 (0.66–1.12) | 0.89 (0.68–1.15) |
| Cohabitation status c | |||
| Living alone | 70 | 1 (reference) | 1 (reference) |
| Cohabitating | 76 | 1.11 (0.92–1.34) | 1.13 (0.93–1.37) |
Abbreviations: CI: confidence interval; PR: prevalence ratio.
aAdjusted for age.
bFollowing the International Standard Classification of Education (ISCED) [39], divided into categories based on years of education:’ short’ (<10 years),’ medium’ (10–15 years), and’ high’ (>15 years).
cDivided into: ‘living alone’ (unmarried, divorced, or widowed) and ‘cohabitating’ (married or registered as living with a partner).
Discussion
Main findings
Half of the women with BCR had an index consultation in general practice, one third presented with symptoms, and nearly half had their diagnostic pathway initiated by the GP. No statistically significant associations were found between SEP and the likelihood of having an index consultation in general practice, presenting with symptoms in general practice, or having the diagnostic pathway initiated by the GP.
Strengths and limitations
A main strength of the study is the use of a validated register-based algorithm to identify patients with BCR (sensitivity of 97.3% and specificity of 97.2%), as recurrences are not routinely and completely registered [35]. Other key strengths include the unique GP-reported data on diagnostic pathways, which are not available in registers, and the use of high-quality register-based SEP data derived from Danish registries generally considered to have a high validity and coverage [41,42].
The study is susceptible to information and selection bias. To reduce the risk of false positive recurrence status, the BCR diagnosis was confirmed by the GP. Patients with severe comorbidity or frailty may potentially have been missed by the algorithm due to lower likelihood of undergoing biopsy or cancer treatment [35]. The risk of recall bias was reduced by the GP’s use of medical records. Misclassification of register-based SEP data is expected to be minimal. Even though some degree of misclassification of GP-reported outcomes cannot be excluded, such misclassification is most likely non-differential, which would generally be expected to lead to an underestimation of the association between SEP and the study outcomes [43]. The GP response rate was 51.3%, which is comparable to that reported in other recent Danish studies using GP survey data [44]. Surveying GPs rather than patients likely mitigated selection bias and allowed for the inclusion of deceased patients. Substantial non-response bias is considered unlikely as patient characteristics, including educational level and cohabitation status, were similar between GP respondents and non-respondents.
A limitation is that a small number of events in some subgroups precluded full adjustment for covariates in all analyses, and data on the clinical characteristics of recurrences were not available. Consequently, residual confounding cannot be ruled out and may have affected the estimates. Particularly, in the analysis of diagnostic pathway initiation in general practice, the limited number of events may have reduced statistical precision as reflected in the wide CIs. However, even in the analyses with large numbers and full adjustment, the CIs remained relatively wide, and no substantial differences were seen between adjusted and unadjusted estimates. The wide variation in time since primary diagnosis suggests that patients differed in their degree of contact with specialised follow-up care at the time of recurrence diagnosis. Findings from the underlying cohort across multiple cancer types demonstrate that GP-involvement in recurrence pathways varies according to follow-up status, as the GPs initiated diagnostic pathways more often after completed follow-up than during active follow-up [6]. Adjustments for time since primary diagnosis and follow-up status were included in the analyses of SEP and index consultation in general practice. After adjustment, no statistically significant associations between SEP and index consultation in general practice were observed. However, due to limited number of events, adjustment for these variables was not possible in the other analyses.
Although nationwide register data covering the total population with information on the study outcomes could have enabled larger subgroup analyses, improved statistical precision, and further reduced the risk of selection bias, no Danish registries currently contain information on symptom presentation and GP involvement in the recurrence pathway.
Interpretation and comparison with previous literature
Our findings align with a previous Danish study, which found that among patients attending outpatient follow-up at time of recurrence, nearly half of BCR cases were detected following referral from a GP or another specialist [7]. In the present study, GPs were involved in a substantial proportion of recurrence pathways with half of the patients having an index consultation in general practice and 43.6% having their diagnostic pathway initiated in general practice, including pathways involving both symptomatic and asymptomatic presentations. These findings point to an important role of general practice in the pathway to BCR diagnosis.
In the present study, patients with BCR were relatively evenly distributed across age groups, supporting continued awareness of possible recurrence, regardless of age. The importance is highlighted by other findings from the present dataset showing that younger patients seem to experience the longest diagnostic intervals for recurrence across multiple cancer types [6].
The median time from primary diagnosis to BCR was comparable to that in a recent Swedish cohort study, which reported a median of 4.3 years [interquartile range 2.1–8.2] [5]. The consistent findings illustrate the heterogeneity in the timing of BCR. Moreover, a Danish study demonstrated a continuously increasing cumulative incidence proportion of BCR over an 8-year study period [14]. Together, the findings suggest that sustained awareness of signs and symptoms of recurrence is important among patients, GPs and other healthcare professionals involved in survivorship care, as Danish BC follow-up recommendations emphasise needs-based access to assessment and diagnostic workup in case of relevant symptoms [10].
To the best of our knowledge, no studies have investigated the association between SEP and the outcomes examined here among patients with BCR. Socioeconomic inequalities have been reported in several areas of the cancer continuum across cancer types, including stage at diagnosis, treatment, and survival [45,46]. In this study, however, we found no statistically significant associations between SEP and the investigated steps of the diagnostic pathway for BCR in general practice, although small differences in point estimates were observed across SEP groups and outcomes. The findings are generally reassuring in the context of the Danish healthcare system. Although socioeconomic differences in cancer awareness [27], barriers in healthcare-seeking, and beliefs about cancer [28] have previously been described, one possible explanation for the absence of a socioeconomic gradient across the investigated GP-related steps is that general practice may represent a point of relatively equal access to the healthcare system. International evidence from the general population suggests that socioeconomic inequalities are more pronounced in specialist than in primary care physician visits, with specialist visits generally more common among individuals with higher SEP [8,30]. In addition, another possible explanation is that patients may generally be more aware of the risk of recurrence after a primary BC diagnosis, regardless of SEP, and GPs may be more observant, potentially reducing the influence of educational level and cohabitation status on presenting with symptoms in general practice and having the diagnostic pathway initiated by the GP. To some extent, these factors may be relevant when interpreting the absence of a socioeconomic gradient across the investigated GP-related steps. As we found no statistically significant associations between cohabitation status and presenting with symptoms in general practice, this may reflect that women’s health behaviour is not influenced by partner support alone, as previous research on patient delay among cancer patients suggests that broader support from the social network may also be important for women [47].
Conclusion
The findings of this study add novel insight into the role of SEP on the pathway to BCR diagnosis in general practice. We found no statistically significant associations between SEP and the likelihood of having an index consultation in general practice, presenting with symptoms in general practice, or having the diagnostic pathway initiated by the GP when presenting with symptoms.
Supplementary Material
Acknowledgements
We thank the participating GPs for their contributions.
Ethical approval
In accordance with the General Data Protection Regulation (GDPR), this study was registered in the record of processing activities at the Research Unit for General Practice in Aarhus. Approval from the Danish Committees on Health Research Ethics was not required for this study. Permission to contact GPs, who were subsequently authorised to access medical records without individual patient consent, was granted by the Central Denmark Region (ID: 1-45-70-19-21).
Use of artificial intelligence
ChatGPT (GPT-5) from OpenAI was used for minor language improvements. ChatGPT was used to propose potential synonyms for search terms, to identify potential supplementary relevant literature following initial searches, and to provide brief preliminary perspectives on selected articles. Outputs were critically evaluated and verified through independent literature searches. All original articles were examined in full text.
Disclosure statement
No potential conflict of interest was reported by the authors.
Data availability statement
Under Danish data protection legislation, the dataset may be accessed only by pre-approved collaborative partners.
References
- 1.Amato O, Guarneri V, Girardi F.. Epidemiology trends and progress in breast cancer survival: earlier diagnosis, new therapeutics. Curr Opin Oncol. 2023;35(6):612–619. doi: 10.1097/cco.0000000000000991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Arnold M, Morgan E, Rumgay H, et al. Current and future burden of breast cancer: global statistics for 2020 and 2040. Breast. 2022;66:15–23. doi: 10.1016/j.breast.2022.08.010. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.NORDCAN AotNCR . 10 years prevalence, Proportion per 100 000, Females, age [40-85+]. Accessed 13 February; 2026. https://nordcan.iarc.fr/en/dataviz/prevalence?mode=cancer&group_populations=1&multiple_cancers=1&cancers=180&sexes=2&group_cancers=0&key=crude_rate&survival=10&populations=208&age_start=8.
- 4.Grunfeld E, Mant D, Yudkin P, et al. Routine follow up of breast cancer in primary care: randomised trial. BMJ. 1996;313(7058):665–669. doi: 10.1136/bmj.313.7058.665. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Sartor H, Hagberg O, Hemmingsson O, et al. Breast cancer recurrence in relation to mode of detection: implications on personalized surveillance. Breast Cancer Res Treat. 2025;209(1):85–92. doi: 10.1007/s10549-024-07475-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Grooss K, Rasmussen LA, Christensen KS, et al. Detecting cancer recurrence in general practice: a Danish national cohort study. Br J Gen Pract. 2026;76(765):e275–e283. doi: 10.3399/bjgp.2025.0174. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Saltbæk L, Horsboel TA, Offersen BV, et al. Patterns in detection of recurrence among patients treated for breast cancer. Breast Cancer Res Treat. 2020;184(2):365–373. doi: 10.1007/s10549-020-05847-4. [DOI] [PubMed] [Google Scholar]
- 8.Rubin G, Berendsen A, Crawford SM, et al. The expanding role of primary care in cancer control. Lancet Oncol. 2015;16(12):1231–1272. doi: 10.1016/s1470-2045(15)00205-3. [DOI] [PubMed] [Google Scholar]
- 9.Sisler J, Chaput G, Sussman J, et al. Follow-up after treatment for breast cancer: practical guide to survivorship care for family physicians. Can Fam Physician. 2016;62(10):805–811. [PMC free article] [PubMed] [Google Scholar]
- 10.Danish Breast Cancer Cooperative Group . Brystkræft - opfølgning [Breast cancer - follow-up]. 2025. Accessed 6 September 2025. https://www.dmcg.dk/siteassets/kliniske-retningslinjer/opdelt-paa-dmcg/brystcancer/opfolgning/dbcg_brystkraft–opfolgning_v.1.0_admgodk_030425.pdf.
- 11.The Danish Health Authority . Pakkeforløb for brystkræft [Cancer patient pathway for breast cancer]. 2018. Accessed 16 May 2026. https://www.sst.dk/udgivelser/2018/pakkeforloeb-for-brystkraeft.
- 12.Danish College of General Practitioners . Kræftopfølgning i almen praksis [Cancer follow-up in general practice]. 2019. Accessed 15 May 2026. https://www.dsam.dk/vejledninger/cancer.
- 13.Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). Reductions in recurrence in women with early breast cancer entering clinical trials between 1990 and 2009: a pooled analysis of 155 746 women in 151 trials. Lancet. 2024;404(10461):1407–1418. doi: 10.1016/s0140-6736(24)01745-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Rasmussen LA, Jensen H, Virgilsen LF, et al. Time from incident primary cancer until recurrence or second primary cancer: risk factors and impact in general practice. Eur J Cancer Care (Engl). 2019;28(5):e13123. doi: 10.1111/ecc.13123. [DOI] [PubMed] [Google Scholar]
- 15.Colleoni M, Sun Z, Price KN, et al. Annual hazard rates of recurrence for breast cancer during 24 years of follow-up: results from the International Breast Cancer Study Group Trials I to V. J Clin Oncol. 2016;34(9):927–935. doi: 10.1200/jco.2015.62.3504. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 16.Braunstein LZ, Taghian AG, Niemierko A, et al. Breast-cancer subtype, age, and lymph node status as predictors of local recurrence following breast-conserving therapy. Breast Cancer Res Treat. 2017;161(1):173–179. doi: 10.1007/s10549-016-4031-5. [DOI] [PubMed] [Google Scholar]
- 17.Witteveen A, Vliegen IM, Sonke GS, et al. Personalisation of breast cancer follow-up: a time-dependent prognostic nomogram for the estimation of annual risk of locoregional recurrence in early breast cancer patients. Breast Cancer Res Treat. 2015;152(3):627–636. doi: 10.1007/s10549-015-3490-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 18.Galobardes B, Shaw M, Lawlor DA, et al. Indicators of socioeconomic position (part 1). J Epidemiol Community Health. 2006;60(1):7–12. doi: 10.1136/jech.2004.023531. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Hjorth CF, Kjærulff TM, Thomsen MK, et al. SEPLINE: socioeconomic position in epidemiological research-A National Guideline on Danish Registry Data. Clin Epidemiol. 2025;17:593–624. doi: 10.2147/clep.S520772. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Pinquart M, Duberstein PR.. Associations of social networks with cancer mortality: a meta-analysis. Crit Rev Oncol Hematol. 2010;75(2):122–137. doi: 10.1016/j.critrevonc.2009.06.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.van Maaren MC, Rachet B, Sonke GS, et al. Socioeconomic status and its relation with breast cancer recurrence and survival in young women in the Netherlands. Cancer Epidemiol. 2022;77:102118. doi: 10.1016/j.canep.2022.102118. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 22.Dalton SO, Olsen MH, Johansen C, et al. Socioeconomic inequality in cancer survival - changes over time. A population-based study, Denmark, 1987-2013. Acta Oncol. 2019;58(5):737–744. doi: 10.1080/0284186x.2019.1566772. [DOI] [PubMed] [Google Scholar]
- 23.Trewin CB, Johansson ALV, Hjerkind KV, et al. Stage-specific survival has improved for young breast cancer patients since 2000: but not equally. Breast Cancer Res Treat. 2020;182(2):477–489. doi: 10.1007/s10549-020-05698-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 24.Hjorth CF, Damkier P, Ejlertsen B, et al. Socioeconomic position and prognosis in premenopausal breast cancer: a population-based cohort study in Denmark. BMC Med. 2021;19(1):235. doi: 10.1186/s12916-021-02108-z. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 25.Mottram R, Knerr WL, Gallacher D, et al. Factors associated with attendance at screening for breast cancer: a systematic review and meta-analysis. BMJ Open. 2021;11(11):e046660. doi: 10.1136/bmjopen-2020-046660. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.von Euler-Chelpin M, Napolitano G, Lynge E, et al. Non-participation in breast screening in Denmark: sociodemographic determinants. BMC Public Health. 2024;24(1):2024. doi: 10.1186/s12889-024-19547-x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 27.Hvidberg L, Pedersen AF, Wulff CN, et al. Cancer awareness and socio-economic position: results from a population-based study in Denmark. BMC Cancer. 2014;14(1):581. doi: 10.1186/1471-2407-14-581. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 28.Hvidberg L, Wulff CN, Pedersen AF, et al. Barriers to healthcare seeking, beliefs about cancer and the role of socio-economic position. A Danish population-based study. Prev Med. 2015;71:107–113. doi: 10.1016/j.ypmed.2014.12.007. [DOI] [PubMed] [Google Scholar]
- 29.Sørensen TH, Olsen KR, Vedsted P.. Association between general practice referral rates and patients’ socioeconomic status and access to specialised health care a population-based nationwide study. Health Policy. 2009;92(2-3):180–186. doi: 10.1016/j.healthpol.2009.03.011. [DOI] [PubMed] [Google Scholar]
- 30.Lueckmann SL, Hoebel J, Roick J, et al. Socioeconomic inequalities in primary-care and specialist physician visits: a systematic review. Int J Equity Health. 2021;20(1):58. doi: 10.1186/s12939-020-01375-1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 31.Levinsen AKG, Kjaer TK, Maltesen T, et al. Educational differences in healthcare use among survivors after breast, prostate, lung, and colon cancer - a SEQUEL cohort study. BMC Health Serv Res. 2023;23(1):674. doi: 10.1186/s12913-023-09683-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 32.Christiansen T. Organization and financing of the Danish health care system. Health Policy. 2002;59(2):107–118. doi: 10.1016/s0168-8510(01)00201-9. [DOI] [PubMed] [Google Scholar]
- 33.Gjerstorff ML. The Danish Cancer Registry. Scand J Public Health. 2011;39(7 Suppl):42–45. doi: 10.1177/1403494810393562. [DOI] [PubMed] [Google Scholar]
- 34.Lynge E, Sandegaard JL, Rebolj M.. The Danish National Patient Register. Scand J Public Health. 2011;39(7 Suppl):30–33. doi: 10.1177/1403494811401482. [DOI] [PubMed] [Google Scholar]
- 35.Aagaard Rasmussen L, Jensen H, Flytkjær Virgilsen L, et al. A validated algorithm for register-based identification of patients with recurrence of breast cancer – Based on Danish Breast Cancer Group (DBCG) data. Cancer Epidemiol. 2019;59:129–134. doi: 10.1016/j.canep.2019.01.016. [DOI] [PubMed] [Google Scholar]
- 36.Erichsen R, Lash TL, Hamilton-Dutoit SJ, et al. Existing data sources for clinical epidemiology: the Danish National Pathology Registry and Data Bank. Clin Epidemiol. 2010;2:51–56. doi: 10.2147/clep.s9908. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 37.Andersen JS, Olivarius Nde F, Krasnik A.. The Danish National Health Service Register. Scand J Public Health. 2011;39(7 Suppl):34–37. doi: 10.1177/1403494810394718. [DOI] [PubMed] [Google Scholar]
- 38.Erlangsen A, Fedyszyn I.. Danish nationwide registers for public health and health-related research. Scand J Public Health. 2015;43(4):333–339. doi: 10.1177/1403494815575193. [DOI] [PubMed] [Google Scholar]
- 39.UNESCO . International Standard Classification of Education ISCED 2011. Montreal, Quebec: UNESCO Institute for Statistics; 2012. [Google Scholar]
- 40.Charlson ME, Pompei P, Ales KL, et al. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5):373–383. doi: 10.1016/0021-9681(87)90171-8. [DOI] [PubMed] [Google Scholar]
- 41.Sørensen ST, Kristensen FP, Troelsen FS, et al. Health registries as research tools: a review of methodological key issues. Dan Med J. 2023;70(4):A12220796. [PubMed] [Google Scholar]
- 42.Jensen VM, Rasmussen AW.. Danish Education Registers. Scand J Public Health. 2011;39(7 Suppl):91–94. doi: 10.1177/1403494810394715. [DOI] [PubMed] [Google Scholar]
- 43.Rothman KJ, Greenland S, Lash TL.. Modern epidemiology. 3rd ed. Philadelphia (PA): Wolters Kluwer Health/Lippincott Williams & Wilkins; 2008. [Google Scholar]
- 44.Sætre LMS, Naamansen SB, Balasubramaniam K, et al. Follow-up cancer care in Danish general practice: a questionnaire study. BJGP Open. 2024;8(2):BJGPO.2023.0215. doi: 10.3399/bjgpo.2023.0215. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 45.Ammitzbøll G, Levinsen AKG, Kjær TK, et al. Socioeconomic inequality in cancer in the Nordic countries. A systematic review. Acta Oncol. Nov. 2022;61(11):1317–1331. doi: 10.1080/0284186x.2022.2143278. [DOI] [PubMed] [Google Scholar]
- 46.Olsen MH, Kjær TK, Dalton SO.. Social Inequality in Cancer in Denmark. ; 2023. Accessed 28 June 2026. https://mediebibliotek.cancer.dk/m/7484eb8e03945662/original/Whitepaper_2023_Social_Inequality_in_Cancer.pdf.
- 47.Pedersen AF, Olesen F, Hansen RP, et al. Social support, gender and patient delay. Br J Cancer. 2011;104(8):1249–1255. doi: 10.1038/bjc.2011.87. [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
Under Danish data protection legislation, the dataset may be accessed only by pre-approved collaborative partners.