Sentinel lymph node biopsy (SLNB) is used to assess axillary involvement in patients with early-stage breast cancer and clinically node-negative axillae. In the late twentieth century, SLNB replaced axillary lymph node dissection after randomized trials demonstrated similar survival rates but lower morbidity.^(1,2)

Over the last few years, new advances have resulted in the de-escalation of axillary surgery. A randomized clinical trial with a 10-year follow-up period (ACOSOG Z0011) evaluated the omission of axillary lymph node dissection in patients with early-stage breast cancer, clinically node-negative axillae, and up to two positive axillary sentinel lymph nodes undergoing breast-conserving treatment and radiation therapy and the study found similar overall survival and local recurrence rates between patients who underwent axillary dissection and those who did not.⁽³⁾

Therefore, SLNB may not confer significant benefits and, in some situations, may even increase associated morbidity. Moreover, reducing axillary interventions may improve patient quality of life and decrease treatment-related morbidity. In patients aged 70 years or older with luminal tumors and clinically node-negative axillae, the "Choosing Wisely" campaign recommends avoiding sentinel lymph node biopsy.^(4,5)

Within this framework, the SOUND randomized study, published in 2023, demonstrated that omission of the SLNB procedure is non-inferior to SLNB in patients with early-stage breast cancer and clinically and ultrasonographically node-negative axillae. These results provide further support for SLNB de-escalation in breast cancer surgery, suggesting that patients with small tumors (diameter ≤2cm) and a negative result on preoperative ultrasound may safely avoid SLNB.⁽⁶⁾ Although the SOUND trial has had a significant impact on the decision-making of medical professionals, SLNB remains necessary for staging in many situations, such as in younger women (<50 years), patients undergoing mastectomy, those with human epidermal growth factor (HER2)-positive or triple-negative disease, or those undergoing neoadjuvant chemotherapy.^(6,7)

Nevertheless, de-escalation of axillary surgery, including omission of SLNB in early-stage breast cancer, is not yet routinely performed in clinical practice by surgical specialists.^(8,9)

Owing to the high prevalence of breast cancer and its impact on public health, characterizing how breast disease is managed by specialists in Brazil is essential. Advances in this area may significantly improve the quality of life of patients with breast cancer and help optimize public health costs. Therefore, the aim of this study was to

To analyze the factors associated with the breast surgeons’ decision-making regarding the omission of sentinel lymph node biopsy in Brazil.

In our study, of 274 doctors, 158 (57.7%) reported omitting SLNB, while 116 (42.3%) did not omit the procedure. The mean age of the participants was 48.6 years (46-50 years). The mean duration of practice in the specialty was 15.1 years. Medical residency in Breast Disorders was the most common residency, with 186 professionals (67.9%), while Radiation Therapy was the least frequent, with 0 (0%) professionals. Details of the study population and results of the univariate analysis are described in table 1.

Having completed medical residency in surgical oncology, having a specialist degree in breast disorders (TEMA), duration of practice in the specialty, sphere of professional practice, holding a Master's degree, holding a doctoral degree, use of the FICT, criteria used to exclude the approach, the technique used, and the number of cases operated without SLNB were considered significant factors (p<0.05) in the univariate analysis (Table 1). Based on p-values and greater clinical relevance, the following were selected for multivariate analysis: medical residency in surgical oncology, having a specialist degree in breast disorders (TEMA), duration of practice in the specialty, sphere of professional practice, holding a Master's degree, and holding a doctoral degree.

The final logistic regression model is described in table 2, where statistical significance was observed for the sphere of professional practice (specialists from the private sector had a greater tendency to omit SLNB) and for holding a doctoral degree. The remaining variables (medical residency in surgical oncology, having a specialist degree in breast disorders, duration of practice in the specialty, and holding a Master's degree) were excluded from the final model to avoid loss of accuracy and model significance.

The goal of surgical de-escalation via SLN biopsy omission is to reduce the morbidity associated with the surgical treatment of specific types of breast cancer, such as pain, lymphedema, and restriction of arm/shoulder mobility, all of which significantly impact the patients’ long-term quality of life.⁽⁵⁾

In this study, 158 practicing breast cancer surgeons (57.7%) reported omitting SLNB in patients with early-stage breast cancer. The literature suggests a slow adoption of updated protocols and guidelines for SLNB in several countries, which may explain the relatively balanced proportion of practitioners who omit SLNB and those who continue to perform it.⁽¹⁰⁾ Furthermore, although studies have shown that omission of SLNB does not adversely affect overall patient survival, its omission remains a concern to some specialists given that SLNB can influence systemic treatment decision-making and patient outcomes. This uncertainty can generate considerable apprehension among physicians regarding patient outcomes. Such concerns may partly explain the lack of a clear predominance of specialists who report omitting SLNB.^(9,11,12)

In 2016, the Choosing Wisely campaign recommended against routine SLNB in patients aged 70 years or older with clinical stage I breast cancer, and those with luminal tumors, HER-2-receptor-negative disease, and clinically node-negative axillae, due to the lack of impact on oncological outcomes.⁽⁸⁾ The main study supporting this recommendation is the CALGB 9343 study; however, other current guidelines and recommendations also demonstrate that SLNB may not be necessary in patients older than 70 years of age and/or with poor performance status who have T1cN0 tumors that are HER2-negative and hormone receptor-positive, particularly when the indication for systemic treatment and/or radiation therapy would not be influenced by the result.^(13–16)

In the current study, among the professionals who reported omitting SLNB, 100 (63.29%) used the following omission criteria: patients older than 70 years, those with HER2-negative luminal tumors, and those who were clinically and ultrasonographically node-negative; these criteria align with the descriptions in the literature. Axillary involvement in early-stage breast cancer is uncommon and may not justify SLNB given the potential morbidity associated with the procedure and the possibility that the risks outweigh the potential benefits.⁽¹⁷⁾

In addition, among the surgeons who reported the use of surgical de-escalation, the rate of axillary node-only recurrence was approximately 2.5%. Although this rate is not a determining factor in the decision-making process, it corroborates findings from clinical trials showing a low recurrence rate when SLNB is omitted, supporting the safety of this breast cancer management strategy. However, this rate may be susceptible to recall bias among practitioners who responded to the questionnaire, as these axillary recurrences could not be independently verified.^(18,19)

Similarly, the European Oncology Institute reported no difference in overall survival among patients who did not undergo axillary surgery, and similar results were reported in another Swedish randomized trial.^(20,21) In contrast, a French study demonstrated poorer survival outcomes in patients who did not undergo axillary surgery. To explain these discordant findings compared to those of previous studies, the authors noted that chemotherapy was more frequently administered to the group that underwent axillary surgery. They emphasized that long-term follow-up is required to confirm or refute these initial observations.⁽²²⁾

Moreover, data from The Surveillance, Epidemiology, and End Results (SEER) database were evaluated to determine the implementation rate of the Choosing Wisely recommendations in the United States. Multivariate analysis showed that the main factors associated with axillary surgery were Hispanic ethnicity, family income between $35,000 and $70,000, treatment provided in rural areas, undifferentiated tumors, lobular or mixed lobular-ductal histology, T2 tumors, and the use of radiation or systemic therapy. The median number of lymph nodes removed was two, with lymph node involvement occurring in only 2.1% of cases, highlighting the need for increased implementation of the Choosing Wisely recommendations in real-life clinical practice.⁽²³⁾

In Brazil, the ongoing VENUS randomized study is evaluating the omission of SLNB in patients with early-stage breast cancer and clinically node-negative and ultrasound-negative axillae. This study includes patients with tumors measuring up to 5 cm, undergoing either breast-conserving surgery or mastectomy, with or without neoadjuvant chemotherapy, and is predicted to conclude in October 2025.⁽²⁴⁾

Based on the results of this study and the available literature, the decision to omit SLNB appears to be multifactorial, considering both the patient status and characteristics of the disease, as well as the wide variations in the perspective of medical specialists regarding the performance of SLNB. For example, in our sample, 81 professionals (29.6%) with more than 20 years of medical experience reported omitting SLNB, whereas. only eight (2.9%) with 1-3 years of experience reported omitting SLNB. This finding suggests that longer practicing duration was associated with a greater tendency to omit SLNB, possibly reflecting increased confidence in clinical judgment developed over years of practice. This observation is consistent with studies indicating that both physician experience and patient preference can influence treatment decisions.^(12,25)

In this context, factors related to higher levels of medical training may also influence the decision-making process. Among the respondents, 165 (60.2%) did not hold a Master's degree, and within this group, 87 (31.7%) reported omitting SLNB, and 78 (28.5%) did not. In contrast, of 109 (39.8%) respondents holding a Master's degree, 71 (25.9%) reported omitting SLNB, while only 38 (13.9%) did not, suggesting a greater tendency to omit SLNB among those with a higher academic training. Similarly, among the 59 (21.532%) respondents who held a doctoral degree, 45 (16.4%) reported omitting SLNB, whereas 14 (5.1%) did not. Therefore, omission of SLNB was more prevalent among those holding a doctoral degree than among those without one.

Variables such as holding a specialist degree in breast disorders (TEMA) and the sphere of professional practice, particularly working in the private sector, were also statistical significant factors influencing the decision-making process, possibly reflecting a greater level of professional updating among these physicians.

Although surgical de-escalation in breast cancer is a current and impactful topic, no large studies with a similar profile to ours, including consideration of the technical aspects of surgery and practitioner profile, have been conducted. The current study included a relatively larger sample size, which increases confidence in the findings. However, as the sample was not randomized, but instead obtained through professional groups and social media, selection bias cannot be ruled out; that is, specialists who omit SLNB may have been more likely to respond to the questionnaire. Therefore, further studies are warranted to better elucidate the factors associated with the omission of SLNB among Brazilian breast specialists. Such evidence could support the development of continuing medical education initiatives aimed specifically at younger specialists, those who do hold a doctoral degree, and those who work in the public sector.

Among the Brazilian surgeons evaluated, a considerable proportion reported omitting SLNBs in patients with early-stage breast cancer. The factors most strongly associated with this practice included working in the private sector and holding a doctoral degree.