INTRODUCTION — The lymphatic drainage pathways of the breast (axillary, internal mammary [IM], and supraclavicular nodal groups) are the regional areas most likely to be involved with metastatic breast cancer.

The risk of metastatic breast cancer to regional lymph nodes, the preoperative assessment of the axilla, and the indications and extent of an axillary dissection, as well as complications, are reviewed in this topic. The techniques for performing a sentinel lymph node dissection, an axillary dissection, and the management of the axilla in the clinical setting of a mastectomy are discussed elsewhere.

●(See "Overview of sentinel lymph node biopsy in breast cancer".)

●(See "Sentinel lymph node biopsy in breast cancer: Techniques".)

●(See "Technique of axillary lymph node dissection".)

●(See "Mastectomy".)

RISK FACTORS FOR LYMPH NODE INVOLVEMENT IN BREAST CANCER

Axillary lymph nodes — The axillary lymph nodes (ALNs) receive 85 percent of the lymphatic drainage from all quadrants of the breast; the remainder drains to the internal mammary, infraclavicular, and/or supraclavicular lymph nodes. The likelihood of ALN involvement is related to tumor size and location, histologic grade, and the presence of lymphatic invasion [1,2]. The presence of axillary metastases is also independently related to intrinsic tumor biology and the time the primary tumor has been present; these observations are not well documented in the literature.

Tumor size and margins — Larger tumors are associated with a higher likelihood of axillary involvement, and the likelihood of ALN involvement increases as the size of the primary tumor increases [3-5]. In a series of 2282 women with invasive breast cancer or ductal carcinoma in situ (DCIS), the incidence of ALN involvement was as follows [5]:

●Tis – 0.8 percent

●T1a – 5 percent

●T1b – 16 percent

●T1c – 28 percent

●T2 – 47 percent

●T3 – 68 percent

●T4 – 86 percent

Similar findings were reported in a contemporary series of 6800 women diagnosed with invasive breast cancer after screening mammography (table 1) [6]. Thus, ALN metastases are relatively common even with invasive breast cancers ≤1 cm in size [1,2,7-10]. In a report of 919 women who underwent ALN dissection (ALND), ALN metastases were detected in 16 and 19 percent of those with T1a (tumor size 0.1 to 0.5 cm in greatest dimension) and T1b tumors (tumor size 0.5 to 1.0 cm), respectively [10]. (See "Tumor, Node, Metastasis (TNM) staging classification for breast cancer".)

ALN positivity rates are higher in women who are found to have residual tumor after re-excision for positive margins following partial mastectomy, as compared with those whose tumors were either excised to a negative margin initially or who had negative re-excisions for an initially positive margin [11]. This is likely attributable to an underestimate of tumor burden. Tumor size is generally recorded as the largest dimension on the first excision. If there is even a moderate amount of residual disease at re-excision, the initial excision may have underestimated the true volume of the lesion.

Histologic features — Low-grade (grade 1) tumors have a significantly lower rate of ALN metastases compared with grade 2 or 3 tumors [9]. As an example, in data derived from the Surveillance, Epidemiology, and End Results (SEER) database, the incidence of ALN involvement in patients with grade 1 and grade 3 tumors of similar size was 3.4 and 21 percent, respectively [9].

Tumors that are associated with a less than 5 percent risk of ALN metastases include those with a single focus of microinvasion [12,13], <5 mm grade 1 tumors without lymphatic invasion, and pure mucinous or pure tubular carcinomas <1 cm [14,15]. (See "Pathology of breast cancer".)

The reported incidence of ALN metastases in modern series of women with DCIS ranges from 0 to 4 percent. This is generally accepted to be due to the presence of a small, undetected invasive component rather than the ability of pure DCIS to metastasize to the axilla. Thus, axillary dissection is not routinely performed in women who have pure DCIS. (See "Breast ductal carcinoma in situ: Epidemiology, clinical manifestations, and diagnosis" and "Ductal carcinoma in situ: Treatment and prognosis" and "Microinvasive breast carcinoma".)

Tumor location — ALNs are more commonly involved with tumors involving the lateral rather than the medial portion of the breast [3,16,17]. The most likely explanation for this difference is preferential drainage of some medial tumors to the internal mammary (IM) nodes [18].

Internal mammary lymph nodes — Like the ALNs, the IM nodes receive lymph drainage from all quadrants of the breast [19]. However, medial tumors have a significantly higher rate of IM nodal metastases [20]. Although the IM nodal chain extends from the fifth intercostal space to the retroclavicular region, nodes in the upper three interspaces are most likely to contain metastases [21-23].

Isolated IM nodal metastases are infrequent; more often, axillary nodes are involved as well [18,20,24]. In a report of over 7000 cases in which the IM and ALNs were examined, IM metastases were detected in 22 percent but were the only site of metastases in 4.9 percent [18]. Isolated IM involvement was more frequent for medial than lateral tumors (7.6 versus 2.9 percent).

As with axillary nodes, it is possible to have reactive IM nodes after breast biopsy that can confound imaging results. Positron emission tomography (PET) scans and integrated PET/computed tomography (CT) may reveal IM nodal disease that is unrecognized by conventional staging methods, but neither of these modalities can provide pathologic confirmation [25]. The use of PET-CT in staging breast cancer patients is discussed elsewhere. (See "Clinical features, diagnosis, and staging of newly diagnosed breast cancer".)

The IM nodes can be classified as pN1, pN2, or pN3, depending on the method of detection and the presence or absence of coexistent regional nodal disease. The American Joint Committee on Cancer (AJCC) Cancer Staging Manual classifies metastasis to internal mammary nodes as pN1 if they are detected by sentinel lymph node dissection (SLND) but not clinically detected, pN2 if they are clinically detected in the absence of axillary lymph node metastases, and pN3 if they are clinically detected in the presence of axillary lymph node metastases [26]. The prognosis is worse when both axillary and IM nodal groups are involved with tumor [23,27-29]. (See "Tumor, Node, Metastasis (TNM) staging classification for breast cancer".)

The management of IM nodes is controversial. Sentinel lymph node (SLN) mapping often identifies nonaxillary nodes, although the ability to identify these nodes does not imply a clinical benefit for biopsy or removal. Following four early randomized trials showing no survival benefit from extended mastectomy (which included IM nodal dissection) as compared with radical or modified radical mastectomy (even in the absence of chemotherapy), routine dissection of IM nodes was abandoned [30-33]. Furthermore, the widespread use of adjuvant systemic therapy for women with both node-positive and node-negative breast cancer has diminished the importance of the IM nodes in clinical care.

However, results from randomized trials testing the value of postmastectomy radiation therapy and a meta-analysis by the Early Breast Cancer Trialists Collaborative Group (EBCTCG) provide high-level evidence that local-regional tumor control is associated with long-term survival benefits [34]. These benefits have been limited to trials that used systemic therapy, which may explain why earlier randomized trials (in which adjuvant systemic therapy was not routinely administered) failed to show a survival benefit from resection of the IM nodes. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer" and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'RT of internal mammary nodes'.)

A benefit for regional nodal irradiation has also been shown in selected women undergoing whole breast radiation therapy (RT) as a component of breast-conserving therapy (BCT). (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer".)

Supraclavicular lymph nodes — Supraclavicular metastases are usually associated with extensive ALN involvement and are rare in its absence. As an example, in a series of 274 women undergoing routine supraclavicular dissection, supraclavicular metastases were found in 18 and 0.7 percent of those with and without ALN metastases, respectively [35].

Supraclavicular metastases are considered a late stage of regional metastatic involvement; however, some patients have a long disease-free survival with aggressive combined modality therapy [36]. The AJCC Cancer Staging Manual classifies metastasis to supraclavicular nodes as N3c rather than M1 disease [26]. (See "Tumor, Node, Metastasis (TNM) staging classification for breast cancer" and "Clinical features, diagnosis, and staging of newly diagnosed breast cancer", section on 'Staging' and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer".)

ASSESSMENT OF THE AXILLA — Physical examination is neither a sensitive nor reliable method to ascertain the status of the axillary lymph nodes because metastatic lymph nodes are often not palpable, and reactive lymph nodes may be mistaken for metastases. The positive predictive value of clinical palpation (ie, likelihood of finding axillary metastases in a patient with suspicious findings on physical examination) ranges from 61 to 84 percent, while the negative predictive value (ie, the likelihood that axillary nodal metastases are absent in a patient with no suspicious findings on physical examination) is only 50 to 60 percent [37-39]. Thus, surgical evaluation is indicated, even in the setting of a clinically negative axilla, if it will change clinical management. Selected older women with small (≤2 cm) estrogen receptor (ER)-positive tumors who will receive adjuvant endocrine therapy and who are clinically node negative may be managed without axillary surgery. (See "Overview of the approach to early breast cancer in older women", section on 'Management of the axilla'.)

Histologic examination of removed lymph nodes is the most accurate method for assessing spread of disease to these nodes.

For clinically node negative patients, or for patients without confirmed histologic cancer in a palpable node, sentinel lymph node mapping and excision accurately predicts the lymph node status, thereby avoiding axillary lymph node dissection in sentinel lymph node negative patients. For patients with clinically palpable or suspicious axillary nodes, axillary ultrasound with fine needle aspiration or core biopsy may identify patients who may be candidates for axillary lymph node dissection rather than sentinel lymph node biopsy.

Axillary ultrasound — For clinically palpable or suspicious axillary nodes, axillary ultrasound with fine needle aspiration or core biopsy may identify patients who may be candidates for axillary lymph node dissection rather than sentinel lymph node biopsy. For clinically node negative patients, or for patients without confirmed histologic cancer in a palpable node, sentinel lymph node mapping and excision accurately predicts the lymph node status, thereby avoiding axillary lymph node dissection in sentinel lymph node negative patients. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Indications'.)

Sentinel lymph node biopsy — In patients with clinically node negative breast cancer, sentinel lymph node dissection (SLND) identifies patients without axillary node involvement, thereby obviating the need for more extensive surgery. The decision about proceeding with axillary lymph node dissection (ALND) is based on the results of SLND, primary tumor size, and other factors. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Management after sentinel lymph node biopsy'.)

Axillary dissection — ALND has historically been a routine component of the staging and management of breast cancer [40]. However, SLND is now accepted as the initial approach for women with early-stage breast cancer. Accordingly, the use of full ALND for staging purposes in clinically node negative patients is contraindicated [41].

The potential benefits of ALND for patients with clinically positive axillary lymph nodes include its impact on disease control (ie, axillary recurrence), its prognostic value, and its role in treatment selection. Histologic examination of removed lymph nodes at the time of ALND is thought to be the most accurate method for assessing spread of disease to these nodes. The anatomic disruption caused by ALND may result in lymphedema, nerve injury, and shoulder dysfunction, which compromise functionality and quality of life. Thus, the role of ALND in breast cancer management has been questioned, particularly in older women who are receiving tamoxifen. (See "Overview of the approach to early breast cancer in older women", section on 'Management of the axilla'.)

Indications — ALND is indicated for most patients with clinically positive ipsilateral axillary lymph nodes, either by fine needle aspirate or sentinel lymph node biopsy. However, completion axillary dissection may not benefit women with estrogen receptor positive T1 or T2 tumors that are clinically node negative with fewer than three positive sentinel lymph nodes (SLNs) who will be treated with whole breast radiation [42]. The clinical approach to such patients is best resolved on a case-by-case basis, taking into account all of the other risk factors and comorbidities for each patient to determine whether or not to complete the ALND. Patient autonomy should be incorporated in the decision-making process. The management of a positive SLN biopsy is controversial and is discussed in detail elsewhere. (See "Overview of sentinel lymph node biopsy in breast cancer", section on 'Pathologic analysis of nodal metastases' and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer" and "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer", section on 'Indications for regional nodal irradiation'.)

Indications for a completion ALND in the clinical setting of a mastectomy are reviewed separately. (See "Mastectomy".)

ALND is not indicated in most patients with ductal carcinoma in situ. (See "Microinvasive breast carcinoma", section on 'Management of the axilla'.)

Extent of dissection — The number of positive ALNs affects the determination of disease stage and also influences locoregional recurrence rates. The extent of dissection is a tradeoff between the greater morbidity of a more extensive ALND and the possibility of leaving residual untreated axillary disease. In general, a level I and II anatomic ALND is the preferred procedure for axillary assessment. The technique of axillary dissection is discussed in detail elsewhere. (See "Technique of axillary lymph node dissection".)

Axillary sampling (removal of four to six nodes) is an imprecisely defined procedure in which variable amounts of the axillary contents are removed, often without reference to anatomic structures. It has been performed, mainly for staging purposes, in an attempt to reduce the morbidity of ALND [43,44]. One study found that 24 percent of women undergoing axillary sampling were erroneously classified as determined by subsequent complete ALND [45]. This is significantly higher than the false negative rate with sentinel node biopsy (approximately 5 to 10 percent). Thus, axillary sampling does not represent the standard of care. Sentinel node biopsy represents a strategy for directed sampling that increases the probability of identifying positive nodes over undirected sampling techniques, thus allowing fewer nodes to be removed without increasing the axillary failure rate. (See "Overview of sentinel lymph node biopsy in breast cancer" and "Sentinel lymph node biopsy in breast cancer: Techniques".)

The risk of axillary recurrence is inversely related to the number of removed ALNs in a formal axillary lymph node dissection. The axillary failure rates increase when fewer than five lymph nodes (LNs) are removed (5 to 21 percent) as compared with when more than five LNs are removed (3 to 5 percent) [46-48].

Impact of ALND on survival — The impact of the number of resected axillary lymph nodes on survival is unclear. Retrospective reports suggest inferior survival with fewer (often <10) resected ALNs [49-55] while others suggest no prognostic impact [44,56,57]. The available data regarding the presence of a survival advantage for lymphadenectomy over observation alone are conflicting. Some studies have raised the possibility that failure to remove tumor-bearing ALNs could be detrimental in patients with breast cancer:

●In one study of 658 women with a clinically negative axilla, patients were randomly assigned to partial mastectomy alone or partial mastectomy plus ALND [58]. Radiation therapy (RT) was given to both groups, and women who had histologically positive LNs found on ALND received chemotherapy. ALND was associated with significantly better five-year survival (97 versus 93 percent), and a reduced frequency of visceral and supraclavicular metastases and lymph node recurrences. There was a lower incidence of axillary and supraclavicular failures in patients who underwent ALND, although the only patients to receive chemotherapy were in the ALND group, making this a confounding variable because chemotherapy improves survival. However, with longer follow-up, survival rates were similar (approximately 75 percent) in both groups at 10 and 15 years [59].

●A survival benefit for ALND was suggested in a retrospective population-based cohort of 8038 patients treated for T1-2 breast cancer in British Columbia between 1989 and 1998 [60]. ALND had been omitted from the treatment of 4, 8, and 22 percent of women 50 to 64, 65 to 74, and >74 years old, respectively. Despite the fact that all of the clinical factors associated with the omission of ALND were favorable (ie, smaller tumor size, lower histologic grade, absence of lymphovascular invasion), overall and cancer-specific five-year survival rates were significantly worse in those who had not undergone ALND (68 versus 85 percent, and 86 versus 91 percent, respectively). Systemic therapy use and regional relapse rates were comparable between the women who underwent axillary dissection and those who did not in each age-specific cohort. However, locoregional recurrence rates were not significantly higher if ALND was not performed. These data suggest that positive axillary nodes represent an indicator of the propensity for metastatic behavior rather than a nidus for later disease dissemination; in other words, removal would not improve outcomes.

●A similar relationship between ALND and survival was reported in a retrospective review of 257,157 women diagnosed with breast cancer in the Surveillance, Epidemiology, and End Results (SEER) database between 1988 and 2000 [55]. Survival was significantly better among women who underwent lymphadenectomy (table 2), even when controlling for race, use of RT, type of surgery, hormone receptor status, age, and stage. There was a consistent trend toward decreased survival as the ratio of positive to total number of nodes removed increased. The results were similar if SLN cases (which accounted for only 5.6 percent of the population) were included or excluded from the analysis. However, survival differences could be due to the use of lymph node status to influence systemic therapy decisions.

●A meta-analysis of six trials that included over 3000 women who were randomly assigned to ALND or no ALND demonstrated an average improvement in absolute survival of 4.5 percent at 10 years with ALND (range 4 to 16 percent) [61]. However, this analysis was limited by several deficiencies: the trials were conducted over a span of four decades (1951 to 1987), few patients had T1a tumors, none used modern systemic adjuvant chemotherapy, and none enrolled women over the age of 70.

The most frequently quoted data arguing against the need for routine ALND in early-stage breast cancer are from the National Surgical Adjuvant Breast and Bowel Project trial B-04 (NSABP B-04) [62]. Women with clinically node negative invasive breast cancer were randomly assigned to radical mastectomy (which by definition includes ALND), simple mastectomy plus local nodal irradiation, or simple mastectomy with ALND delayed until positive LNs developed. The inability to detect significant differences among the three groups with respect to disease-free or overall survival (approximately 57 percent) at 10 years (and in a later report, with 25 year follow-up [63]) argues against a therapeutic role for ALND.

A subsequent meta-analysis of three randomized trials comparing axillary dissection versus no dissection published between 2000 and 2007 as well as a fourth trial comparing axillary radiotherapy versus no axillary therapy found no difference in overall survival, metastases, or ipsilateral breast recurrence associated with axillary treatment [64]. This may be attributable to the widespread use of adjuvant chemotherapy and RT during this time frame, especially since breast radiation for breast conservation includes at least the low axillary field.

Surgical complications — Major complications of ALND are infrequent but include injury or thrombosis of the axillary vein and injury to the motor nerves. Lymphedema is more common and is generally of the most concern to patients anticipating the procedure. Other complications include seroma formation, shoulder dysfunction, loss of sensation in the distribution of the intercostobrachial nerve, and mild edema of the arm and breast [65]. (See "Clinical features and diagnosis of peripheral lymphedema" and "Technique of axillary lymph node dissection" and "Technique of axillary lymph node dissection", section on 'Complications'.)

Role of axillary surgery in older women treated with adjuvant endocrine therapy — Older women may not require axillary lymph node surgery, because the knowledge gained may not influence adjuvant treatment choice or outcome. At least three randomized trials have addressed this issue, all of which suggest that selected older women who have small (<2 cm) estrogen receptor (ER)-positive tumors who have a clinically uninvolved axilla and who are receiving adjuvant endocrine therapy may be treated without immediate axillary surgery without an adverse effect on outcome [66-68]. Knowledge of the status of the ALNs may not influence treatment recommendations or outcome in patients over 70 years of age when primary tumor characteristics are favorable or comorbid disease is present [69]. The role of axillary assessment in older women with ER-positive breast cancer is discussed in detail elsewhere. (See "Overview of the approach to early breast cancer in older women", section on 'Management of the axilla'.)

AXILLARY RADIATION THERAPY — Standard whole breast radiation includes two tangential radiation fields to the breast or chest wall. Full axillary radiation therapy (RT) is defined as the use of an additional third radiation field and in some cases a fourth field to ensure treatment of the supraclavicular and upper axillary lymph nodes (ALNs). Axillary RT effectively prevents axillary recurrence in patients with clinically negative ALNs [70-74]. (See "Adjuvant radiation therapy for women with newly diagnosed, non-metastatic breast cancer".)

RT versus ALND — Three randomized trials have directly compared locoregional failure rates and survival in women treated with axillary lymph node dissection (ALND) or axillary RT in women with early stage breast cancer:

●In the previously described NSABP B-04 trial, clinically node negative patients were randomly assigned to total mastectomy and ALND, total mastectomy with regional nodal irradiation, or total mastectomy only with delayed ALND at the time of recurrence [62]. Although the 10 year survival was similar in the three groups, the axillary failure rate was significantly higher in the women treated with mastectomy alone (without ALND or RT) (18 percent) compared with those undergoing RT or initial ALND (3.1 and 1.4 percent, respectively). The rate of axillary failure was probably higher than 18 percent in those undergoing delayed ALND because inoperable axillary recurrences and operable axillary recurrences that occurred simultaneously with or after distant metastases were excluded. It should be noted, however, that the time period for this study was 1971 to 1974, when the use of mammographic screening was neither widespread nor as sophisticated as it is presently. The mean tumor size in this study was generally larger than currently identified. Since the likelihood of subclinical axillary metastases increases with increasing tumor size, we would anticipate that axillary failure rates without dissection or radiation today would be significantly lower than 18 percent, especially in light of our current adjuvant chemotherapy regimens.

●In a study of women who were randomly assigned to partial mastectomy and RT with or without ALND, patients with histologically positive ALNs also received RT to the supraclavicular and internal mammary (IM) nodes plus chemotherapy, while those with medial or central lesions received IM nodal irradiation [58]. At a mean follow-up of 54 months, the RT-alone group had a higher rate of axillary failure (2.1 versus 0.9 percent) and a significantly lower rate of survival (93 versus 97 percent). However, in a later report with median 180 month follow-up, both the 10 and 15 year survival rates were similar (73.8 versus 75.5 percent at 15 years, respectively), despite the threefold higher axillary recurrence rate with RT alone (3 versus 1 percent, respectively) [59], further underscoring that recurrent or residual axillary disease does not directly lead to distant recurrence.

●In a trial of 381 women undergoing breast-conserving therapy (BCT) for tumors <1 cm in diameter, those who had a clinically negative axilla were randomly assigned to ALND or axillary RT. In a preliminary report with a median follow-up of 26 months, only one axillary recurrence was noted in each treatment arm [75].

All three trials show low rates of axillary failure after either ALND or axillary RT and similar long-term survival. Thus, whether ALND is therapeutic for a subset of patients remains debatable. Only those women with ALN involvement have the potential to benefit from ALND because removal of normal nodes should not alter survival. For this reason, identification of patients who have involved ALNs by a less morbid procedure, such as SLN biopsy or axillary ultrasound with fine needle aspiration or core biopsy, is recommended. (See "Overview of sentinel lymph node biopsy in breast cancer" and "Sentinel lymph node biopsy in breast cancer: Techniques".)

Complications of axillary radiation — Although treatment with either surgery or RT reduces the rate of axillary recurrence, the benefit must be balanced against the risk of treatment-related morbidity. In general, the rate of complications is higher in women undergoing surgery and RT compared with RT alone [72,76]. This topic is discussed elsewhere. (See "Patterns of relapse and long-term complications of therapy in breast cancer survivors", section on 'Long-term adverse effects of primary therapy'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Breast surgery".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Beyond the Basics topics (see "Patient education: Breast cancer guide to diagnosis and treatment (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●The status of the axillary lymph nodes is one of the most important prognostic factors in women with early stage breast cancer. Histologic examination of removed lymph nodes is the most accurate method for assessing spread of disease to these nodes. (See 'Introduction' above.)

●For patients who have clinically negative axillary lymph nodes, sentinel lymph node biopsy reliably identifies patients without axillary node involvement, thereby obviating the need for more extensive surgery. (See 'Sentinel lymph node biopsy' above.)

●Axillary lymph node dissection (ALND) remains the standard approach for women who have three or more positive sentinel nodes or those who have a positive fine needle aspiration of a clinically suspicious axillary lymph node. Completion axillary dissection may not benefit women with estrogen receptor (ER)-positive T1 or T2 tumors that are clinically node negative, with fewer than three positive sentinel nodes, who will be treated with whole breast irradiation. The clinical approach to such patients is best resolved on a case-by-case basis, taking into account all of the other risk factors and comorbidities for each patient to determine whether or not to complete the ALND. Patient autonomy should be incorporated in the decision-making process. (See 'Axillary dissection' above and "Overview of sentinel lymph node biopsy in breast cancer", section on 'Management after sentinel lymph node biopsy'.)

●Selected older women who have small ER-positive tumors, a clinically uninvolved axilla, and who are receiving adjuvant hormone therapy may be treated without axillary surgery. (See 'Role of axillary surgery in older women treated with adjuvant endocrine therapy' above.)

●Axillary radiation therapy (RT) may be a reasonable alternative to ALND for clinically node negative patients in whom pathologic nodal status would not alter the therapeutic plan. (See 'Axillary radiation therapy' above.)