Sentinel node in breast cancer as an indicator of quality in medical care: Evaluation of statistics in Colombia

1.Introduction

Sentinel node biopsy in women with breast cancer and clinically negative lymph nodes is considered the standard of care for axillary staging, replacing axillary lymphadenectomy by providing information on lymph node metastatic involvement with minimal morbidity [6].

The safety of sentinel lymph node biopsy in patients with negative nodes was established in the NSABP B-32 trial, which showed no difference in overall survival between patients undergoing axillary lymphadenectomy and those undergoing sentinel node biopsy [27]. In addition, this group has a lower incidence of lymphedema and arm/shoulder morbidity, complications associated with decreased quality of life, and increased costs [32].

Some studies have shown that there is a greater probability of being scheduled for sentinel node biopsy when surgeons specialize or focus on breast cancer [1,26,32,33]. The learning curve for sentinel node biopsy can vary; however, once the multidisciplinary team gains experience with the procedure, identification rates of over 95% are achieved [5]. These results have consolidated this procedure as the technique standard of care in women with breast cancer who meet the selection criteria [18].

Stage I of the anatomical classification of breast cancer by the American Joint Committee on Cancer (AJCC) comprises stage IA with negative nodes and T1 tumor and IB, which is rarely used [25], with microscopic N1 involvement when the tumors are T0 and T1 [17]. Stage II also includes some patients with negative nodes in stages IIA and IIB and patients who have metastases to movable ipsilateral level I and II axillary lymph node(s) (cN1) [17]. The information available on the clinical stages of invasive breast cancer in Colombia groups them into only 4 states, without subdivisions [4]. Therefore, the proportion of patients with negative nodes cannot be determined in stage II. In stage IIIB (T4 N0 M0) or stage III (N1) patients with complete node response after neoadjuvant chemotherapy, sentinel lymph node biopsy was not recommended in Colombia during the years in which the information for this study was collected.

Given that stage I during the years evaluated, presumably is composed entirely of patients with negative nodes (IA) and thus with indication of sentinel node biopsy, it is taken as a reference in the quality evaluation model of breast cancer care in Colombia.

A high-quality cancer care delivery system should incorporate evidence into clinical practice, which involves developing Clinical Practice Guidelines, measuring quality, and improving clinician performance [15]. The Institute of Medicine of the National Academy of Sciences (USA) recommends the use of systematic guidelines based on the best available evidence for prevention, diagnosis, treatment, and palliative care. Therefore, once they are available for one subject of cancer care, it should be done following these guidelines [20].

2.Methods

A search was undertaken in the national database of the Individual Service Provision Registry (RIPS) of the Ministry of Health and Social Protection of Colombia with the sentinel lymph node biopsy codes with staining and radiolabeling and the filters of breast cancer and year. Their results were interpreted with the estimated proportion of their indication, making it equivalent to the stage I breast cancer, and analyzed in the context of their relationship with the quality of medical care. Because the RIPS database does not collect information on sentinel lymph node biopsy by stage groups, the diagnoses of stage I breast cancer were obtained from another source of information that reports the incidence, prevalence, and mortality of the most frequent cancers [4].

3.Results

In Colombia, breast cancer was diagnosed in 24843 cases from 2017 to 2020. Of these, TNM staging was reported in 22154 cases, 3648 in stage I. In the same time frame, the number of sentinel lymph node biopsies for breast cancer in Colombia was 1045, 28.64% of the total cases reported in stage I (Table 1).

4.Discussion

In patients with primary breast cancer and clinically negative nodes, axillary lymphadenectomy has been gradually abandoned. Several randomized studies compare axillary lymphadenectomy with sentinel lymph node biopsy [22], demonstrating lower morbidity and better quality of life with the last procedure due to lower risk of lymphedema, infection, nerve and vessel injury, or shoulder dysfunction [7], with no evidence of long-term adverse effects on survival [8]. Therefore, it is considered the turning point in axillary surgery [6]. These advantages are reflected in the meta-analysis results that support the preferential use of sentinel node biopsy. Routine axillary lymph node dissection does not provide any survival benefit compared with sentinel lymph node dissection in patients with clinically node-negative early-stage breast cancer [31]. Therefore, axillary lymphadenectomy for unaffected clinically and radiologically lymphatic nodes is no longer an acceptable practice in breast cancer [22]. In addition, it has a higher risk of morbidity [23].

The evaluation of costs between these two procedures varies among countries; however, the longer hospital stays and increased risk of lymphedema associated with axillary lymphadenectomy are consistent internationally [10].

Of a projected minimum number of sentinel node biopsy procedures in Colombia by making them equivalent to patients with stage I, the number of sentinel node biopsies obtained constitutes less than one-third of the procedures expected in this stage (although the proportion has progressively increased over the years and in 2020 it was 44.03%). Therefore, despite the evidence in favor of sentinel node biopsy, it is not performed with the expected frequency, thus leading to numerous patients having more complications. This situation is not explained by the poverty of the patients because the health system pays for the procedure, but by administrative decisions that authorize breast interventions in places that are not adequately equipped instead of concentrating the cases in places with human and technological resources that allow the procedure. What happens seems to be caused by organizational limitations and, not by financial constrictions with many cancer patients treated in general hospitals, not in comprehensive cancer centers [13].

Oncology services in Colombia are mostly private (91.1%), and a minimum percentage are public services (7.9%) or mixed (1.0%) [24]. There are national norms regarding the obligation of all sectors (public, private, or mixed) to report the information of patients with breast cancer diagnoses to the corresponding health offices, from where they finally direct it to the Ministry of Health and Social Protection. However, the figures might not be an exact representation of the clinical practice because, despite the mandatory compliance norms and the existence of sanctions in case of non-compliance, it is passive epidemiological surveillance that therefore may have the usual limitations of this system [29].

A key element of quality monitoring is standardized measures of care. These may be used for self-assessment or external review of the quality of care [3], allowing centers to follow patients over time in a standardized manner, and easily recognize when attention is required to improve particular areas of healthcare delivery [14]. The European Society of Breast Cancer Specialists (EUSOMA) includes the sentinel lymph node biopsy as a mandatory quality indicator in the surgery and quality of life section (avoidance of overtreatment). The indicator is described as the proportion of patients with invasive cancer and clinically negative axilla who underwent sentinel lymph node biopsy only (excluding patients who received primary systemic treatment), with a minimum standard of 90% and a target of 95% [14].

A database from EUSOMA started in 2006 showed that 61.5% of patients did not receive axillary clearance (sentinel lymph node only), with an increase in the following years until reaching 96.7% in 2015 [28].

A study in different hospital settings in Portugal found that more than 90% of patients with early-stage breast cancer (stages I or II) and clinically negative axillary nodes underwent sentinel lymph node biopsy [12].

In Colombia, in stage I breast cancer, sentinel lymph node biopsy according to the developed model, is quite far from the minimum recommended standard (28.64% vs 90%) [14], and clearly, the percentage obtained with the model overestimates the real values because it includes some patients in stage II.

Clinical practice guidelines are widely used by medical teams, including physicians, nurses, and pharmacists, as a support tool for providing day-to-day evidence-based care [9]. The guideline of the Ministry of Health and Social Protection of Colombia described the evidence of sentinel node biopsy in breast cancer [21], and it is a recommended procedure in American guidelines [25].

There is consistency in the recommendation of clinical practice guidelines to perform sentinel lymph node biopsy in clinically node-negative early-stage breast cancer cases [16], although its validity should be periodically reviewed to evaluate modifications that arise from new evidence, such as the omission of sentinel lymph node biopsy in patients age ≥70 years with clinically node-negative (T1N0) early-stage invasive breast cancer, that is hormone receptor–positive and human epidermal growth factor receptor 2 (HER2)–negative [19]. In general, adherence to clinical practice guidelines has become a common tool to promote quality and equity of services and control costs [2]. When clinical practice guidelines are followed, clinical outcomes improve [11], which is why they are considered one of the few instruments to improve the quality of cancer care [15].

The low percentage of performance of sentinel lymph node biopsies in Colombia is expected to result in a higher rate of complications and higher costs for the health system. Greater efforts are required in the country to improve the care of patients with breast cancer.

There are several other ways to improve the quality of care. Access to rapid, high-quality diagnosis and multidisciplinary high-quality units is needed as well as advocacy, policy change, innovation, and strengthening of local research and training of specialists and subspecialists [30].

5.Conclusions

Sentinel node biopsy is currently the best approach for axillary staging in patients with clinically node-negative breast cancer. The performance of this procedure is considered to be an indicator of quality. The findings of this study suggest the need to increase the proportion of this surgery. To improve its performance, the management of breast cancer needs to be performed in comprehensive cancer centers in which care is provided by multidisciplinary teams. The government and the companies offering health services must do more to promote the quality of care for breast cancer.