Internal Mammary Sentinel Lymph Node Mapping for Invasive Breast Cancer: Implications for Staging and Treatment

Prognostic significance of the primary tumor site and immune indexes in patients with estrogen receptor-positive, human epidermal growth factor receptor-2-negative breast cancer

BACKGROUND

The ability to predict high risk factors for recurrence after neoadjuvant chemotherapy (NAC) is controversial. The purpose of the present study was to investigate the prognostic significance of tumor location, tumor-infiltrating lymphocyte (TIL) level, and pretreatment lymphocyte-to-monocyte ratio (LMR) in determining the survival of patients with estrogen receptor (ER)-positive, human epidermal growth factor receptor-2 (HER2)-negative breast cancer after treatment with NAC.

METHODS

The clinical data of 285 ER-positive, HER2-negative patients with clinical stage II-III breast cancer were analyzed from January 2009 to January 2015. To explore the prognostic factors for ER-positive, HER2-negative patients, we combined the conventional clinicopathological prognostic factors with tumor location, pretreatment LMR, and TIL. In addition, samples from 79 patients, who did not achieve pathological complete response (pCR) testing after NAC, were selected for hematoxylin-eosin (HE) staining to analyze the effect of TIL on prognosis.

RESULTS

An LMR >5.2 was correlated with better 5-year disease-free survival (DFS) and overall survival (OS; P<0.001 and P<0.001, respectively). Patients with lower-inner/central quadrant tumors had lower 5-year DFS and OS than patients with tumors in the other quadrants (P=0.012 and P=0.048). Patients with a lower TIL level (≤10%) had better 5-year DFS than patients with a higher TIL level (P=0.010). According to the results of the multivariate analyses, tumor location was an independent prognostic factor for 5-year DFS (P=0.021). Pretreatment LMR was associated with both 5-year DFS and OS (P<0.001 and P<0.001, respectively). In the subgroup analysis stratified by TIL level, the TIL level and the initial clinical stage were associated with 5-year DFS (P=0.027 and P<0.001, respectively).

CONCLUSIONS

We explored the prognostic significance of the tumor site, TIL level, and pretreatment LMR level for ER-positive, HER2-negative patients. We concluded that the lower-inner/central quadrant tumors, TIL >10%, and pretreatment LMR level ≤5.2 were correlated with a poor prognosis. More aggressive NAC and/or endocrine therapy with internal mammary node radiotherapy (IMN-RT) should be administered to address the relatively poor prognosis of patients with breast carcinoma presenting the aforementioned adverse factors.

Predictors of internal mammary lymph nodes (IMLN) metastasis and disease-free survival comparison between IMLN-positive and IMLN-negative breast cancer patients: Results from Western China Clinical Cooperation Group (WCCCG) database (CONSORT)

Limited studies performed a comprehensive assessment of risk factors for internal mammary lymph nodes (IMLN) metastasis, and disease-free survival (DFS) difference between IMLN-positive and IMLN-negative breast cancer (BC) patients undergoing IMLN dissection and systemic therapies was not clear.A retrospective study included 1977 BC patients from Western China Clinical Cooperation Group between January 2005 and December 2012. The impact of clinicopathological factors on the occurrence of IMLN metastasis was assessed in univariate and multivariate logistic regression analyses, and a nomogram (model) was constructed to predict the IMLN status. DFS difference was evaluated in univariate and multivariate Cox regression analyses between IMLN-negative and IMLN-positive patients, and univariate analysis was performed to compare DFS between individuals with high and low IMLN metastasis risk defined by proposed nomogram.Of 1977 enrolled patients, 514 cases underwent IMLN dissection and 1463 cases did not undergo IMLN irradiation or dissection. We found that initial disease symptoms and signs, mammographic calcification, tumor site, number of positive axillary lymph nodes (ALNs), American Joint Committee on Cancer pT stage, and human epidermal growth factor receptor 2 status were associated with IMLN metastasis (all P < .05). Those variables were included in nomogram, whose predictive ability was better than that of ALN classification (area under the curve: 0.82 vs 0.76, P < .001). Univariate cox proportional hazards model indicated that better DFS was observed in IMLN-negative patients than IMLN-positive group (hazard ratio [HR] = 1.87, 95% confidence interval [CI] = 1.05-3.34; P = .04), whereas no significant differences in DFS (HR = 0.99, 95% CI = 0.49-2.00; P = .97) were found after adjusting patient-, disease-, and treatment-related factors.Nipple inversion, mammographic calcification, larger tumor size, medial tumor site, negative HER-2 status, and more positive ALNs are independent risk factors for IMLN metastasis, and the individualized nomogram is a feasible tool to predict the status of IMLN. Equivalent DFS was found between positive and negative IMLN patients who all accepted IMLN dissection and systemic therapies.

Sentinel Lymph Node Biopsy in Breast Cancer: Review on Various Methodological Approaches

Aims and background

Sentinel lymph node biopsy has been accepted as a standard procedure for early stage breast cancer. In this retrospective analysis, the results obtained with different methodological approaches using radiocolloid with or without blue dye were examined.

Methods

A total of 158 sentinel lymph node biopsies were performed in 152 patients. Group A (85 patients) underwent lymphatic mapping using a combination of periareolar intradermal radiocolloid and subareolar blue dye injections. Group B (73 patients) underwent only periareolar intradermal radiocolloid injection. One large tin colloid and two small radiocolloids (nanocolloid of serum albumin -NC- and colloidal rhenium sulphide -CS-) were used.

Results

Successful lymphatic mapping was attained in 157 of 158 procedures (99.4%). Radiocolloids localized sentinel lymph nodes in 99.4% and blue dye in 75.3% of the cases. The number of sentinel lymph nodes removed was greater in nanocolloid and colloidal rhenium sulphide groups ( P ≤0.05). Among 60 metastatic sentinel lymph nodes, frozen section analysis using hematoxylin and eosin staining failed to detect 1 macro- and 10 micrometastasis. Radiocolloid uptake was higher in sentinel lymph nodes accumulating blue dye (1643 ± 3216 counts/10 sec vs 526 ± 1284 counts/10 sec, P <0.001). Higher count rates were obtained by using larger sized colloids (median and interquartile range: tin colloid, 2050 and 4548; nanocolloid, 835 and 1799; colloidal rhenium sulphide, 996 and 2079; P = 0.01). Only 2 extra-axillary sentinel lymph nodes were visualized using periareolar intradermal injection modality.

Conclusions

Radiocolloids were more successful than blue dye in sentinel lymph node detection. More sentinel lymph nodes were harvested with small colloids, but different sized radiocolloids were similarly successful. Sentinel lymph nodes having higher radiocolloid uptake tended to accumulate blue dye more frequently. Sentinel lymph nodes manifested higher count rates when a larger colloid was used. Frozen section was very successful in detecting macrometastatic disease in sentinel lymph nodes, but the technique failed in most of the micrometastates.

Validation study for the hypothesis of internal mammary sentinel lymph node lymphatic drainage in breast cancer

According to axilla sentinel lymph node lymphatic drainage pattern, we hypothesized that internal mammary sentinel lymph node (IM-SLN) receives lymphatic drainage from not only the primary tumor area, but also the entire breast parenchyma. Based on the hypothesis a modified radiotracer injection technique was established and could increase the visualization rate of the IM-SLN significantly. To verify the hypothesis, two kinds of tracers were injected at different sites of breast. The radiotracer was injected with the modified technique, and the fluorescence tracer was injected in the peritumoral intra-parenchyma. The location of IM-SLN was identified by preoperative lymphoscintigraphy and intraoperative gamma probe. Then, internal mammary sentinel lymph node biopsy (IM-SLNB) was performed. The fluorescence status of IM-SLN was identified by the fluorescence imaging system. A total of 216 patients were enrolled from September 2013 to July 2015. The overall visualization rate of IM-SLN was 71.8% (155/216). The success rate of IM-SLNB was 97.3% (145/149). The radiotracer and the fluorescence tracer were identified in the same IM-SLN in 127 cases, the correlation and the agreement is significant (Case-base, r_s=0.836, P<0.001; Kappa=0.823, P<0.001). Different tracers injected into the different sites of the intra-parenchyma reached the same IM-SLN, which demonstrates the hypothesis that IM-SLN receives the lymphatic drainage from not only the primary tumor area but also the entire breast parenchyma.

Neuronal Circuits Modulate Antigen Flow Through Lymph Nodes

When pathogens and toxins breech the epithelial barrier, antigens are transported by the lymphatic system to lymph nodes. In previously immunized animals, antigens become trapped in the draining lymph nodes, but the underlying mechanism that controls antigen restriction is poorly understood. Here we describe the role of neurons in sensing and restricting antigen flow in lymph nodes. The antigen keyhole-limpet hemocyanin (KLH) injected into the mouse hind paw flows from the popliteal lymph node to the sciatic lymph node, continuing through the upper lymphatics to reach the systemic circulation. Re-exposure to KLH in previously immunized mice leads to decreased flow from the popliteal to the sciatic lymph node as compared with naïve mice. Administering bupivacaine into the lymph node region restores antigen flow in immunized animals. In contrast, neural activation using magnetic stimulation significantly decreases antigen trafficking in naïve animals as compared with sham controls. Ablating Na_V1.8 + sensory neurons significantly reduces antigen restriction in immunized mice. Genetic deletion of FcγRI/FcεRI also reverses the antigen restriction. Colocalization of PGP9.5-expressing neurons, FcγRI receptors and labeled antigen occurs at the antigen challenge site. Together, these studies reveal that neuronal circuits modulate antigen trafficking through a pathway that requires Na_V1.8 and FcγR.

Internal Mammary Sentinel Lymph Node Biopsy With Modified Injection Technique: High Visualization Rate and Accurate Staging

Although the 2009 American Joint Committee on Cancer incorporated the internal mammary sentinel lymph node biopsy (IM-SLNB) concept, there has been little change in surgical practice patterns because of the low visualization rate of internal mammary sentinel lymph nodes (IMSLN) with the traditional radiotracer injection technique. In this study, various injection techniques were evaluated in term of the IMSLN visualization rate, and the impact of IM-SLNB on the diagnostic and prognostic value were analyzed.Clinically, axillary lymph nodes (ALN) negative patients (n = 407) were divided into group A (traditional peritumoral intraparenchymal injection) and group B (modified periareolar intraparenchymal injection). Group B was then separated into group B1 (low volume) and group B2 (high volume) according to the injection volume. Clinically, ALN-positive patients (n = 63) were managed as group B2. Internal mammary sentinel lymph node biopsy was performed for patients with IMSLN visualized.The IMSLN visualization rate was significantly higher in group B than that in group A (71.1% versus 15.5%, P < 0.001), whereas the axillary sentinel lymph nodes were reliably identified in both groups (98.9% versus 98.3%, P = 0.712). With high injection volume, group B2 was found to have higher IMSLN visualization rate than group B1 (75.1% versus 45.8%, P < 0.001). The IMSLN metastasis rate was only 8.1% (12/149) in clinically ALN-negative patients with successful IM-SLNB, and adjuvant treatment was altered in a small proportion. The IMSLN visualization rate was 69.8% (44/63) in clinically ALN-positive patients with the IMSLN metastasis rate up to 20.5% (9/44), and individual radiotherapy strategy could be guided with the IM-SLNB results.The modified injection technique (periareolar intraparenchymal, high volume, and ultrasound guidance) significantly improved the IMSLN visualization rate, making the routine IM-SLNB possible in daily practice. Internal mammary sentinel lymph node biopsy could provide individual minimally invasive staging, prognosis, and decision making of the internal mammary radiotherapy, especially for clinically ALN-positive patients.

Management of the axilla

The development and wide acceptance of sentinel lymph node biopsy (SLNB) has profoundly affected the management of breast cancer. SLNB has spared the additional morbidity of axillary lymph node dissection (ALND) without compromising diagnostic accuracy and prognostic information in patients with clinically node-negative early-stage breast cancer. It has become an invaluable tool to clinicians to guide decisions regarding adjuvant treatment. The management of breast cancer continues to advance to more minimally invasive approaches, and the role of ALND is likely to become less important in the future.

Blue dye is sufficient for sentinel lymph node biopsy in breast cancer

BACKGROUND

Most previous studies have reported superior results when blue dye and radiocolloids were used together for sentinel lymph node (SLN) biopsy in early breast cancer. Blue dye was reported to perform poorly when used alone, although more recent studies have found otherwise. This study reviewed the authors' practice of performing SLN biopsy with blue dye alone.

METHODS

This was a retrospective review of patients who underwent SLN biopsy using blue dye alone from 2001 to 2005, when SLN biopsy was performed selectively and always followed by axillary lymph node dissection (ALND), and from 2006 to 2010, when SLN biopsy was offered to all suitable patients and ALND done only when the SLN was not identified or positive for metastasis.

RESULTS

Between 2001 and 2005, 170 patients underwent SLN biopsy with blue dye alone. The overall SLN non-identification rate was 8·4 per cent. The overall false-negative rate was 34 per cent, but decreased with each subsequent year to 13 per cent in 2005. From 2006 to 2010, 610 patients underwent SLN biopsy with blue dye alone. The SLN was not identified in 12 patients (2·0 per cent) and no significant contributing factor was identified. A median of 2 (range 1-11) SLNs were identified. A non-SLN was found to be positive for metastasis in two patients with negative SLNs. Axillary nodal recurrence developed in one patient; none developed internal mammary nodal recurrence. Anaphylaxis occurred in one patient.

CONCLUSION

Blue dye performed well as a single modality for SLN biopsy. Non-identification, axillary nodal recurrence and serious allergic reactions were uncommon.

Surgical approach to internal mammary sentinel node biopsy

BACKGROUND

Internal mammary node (IMN) metastasis has a similar prognostic importance as axillary nodal involvement. However, sampling of IMN is not performed routinely.

AIMS

To evaluate a simplified method for internal mammary sentinel node (IMSN) biopsy of breast cancer patients.

METHODS

A combination of simultaneous perilesional and intradermal radiocolloid injections over the lesion was used. All IMSNs were confirmed by lymphoscintigraphy and Carbon Nanoparticles Suspension Injection preoperatively and excised extrapleurally through the intercostal muscles.

RESULTS

Twenty-three of the 94 patients were found to have metastatic disease in the IMSNs. Four of 65 patients had metastases in the IMNs but not in the axilla. All 23 patients with positive IMSN were upstaged and received radiation to the internal mammary chain. The time from separating the pectoral major muscle to touch the node was ranged 21-48 min. The detecting sensitivity combined with preoperative lymphoscintigraphy, intraoperative gamma probe detection, and intraoperative black dye methods for IMSN was 100%.

CONCLUSIONS

The approach used is a reliable surgical technique for removing IMSN. It can improve the nodal staging in breast cancer with IMN metastases.

Recent advances in the surgical care of breast cancer patients

A tremendous improvement in every aspect of breast cancer management has occurred in the last two decades. Surgeons, once solely interested in the extipartion of the primary tumor, are now faced with the need to incorporate a great deal of information, and to manage increasingly complex tasks.

As a comprehensive assessment of all aspects of breast cancer care is beyond the scope of the present paper, the current review will point out some of these innovations, evidence some controversies, and stress the need for the surgeon to specialize in the various aspects of treatment and to be integrated into the multisciplinary breast unit team.

Prognostic implications of positive nonsentinel lymph nodes removed during selective sentinel lymphadenectomy for breast cancer

Nonsentinel lymph nodes (SLNs) are commonly removed at the time of selective sentinel lymphadenectomy (SSL). Their predictive value for the rest of the nodal basin is unknown. A retrospective review of 436 breast cancer patients who underwent SSL between 12/97 and 04/03 at a single institution. One-hundred nineteen patients had non-SLNs removed at SSL; eight were positive (6.7%). Positive non-SLNs predicted that SLNs would also be positive (p = 0.008). There was no difference in rates of additional positive nodes found on completion axillary node dissection between the non-SLN and SLN positive patients (p = 0.62). After adjustment for covariates, the presence of positive non-SLNs was not associated with poorer disease free survival (p = 0.24), time to systemic recurrence (p = 0.57), or overall survival (p = 0.70). Positive non-SLNs removed during SSL are not a significant risk factor for additional positive nodes on completion axillary nodal dissection (CALND) or for worse survival than positive SLNs.

The sentinel node in breast cancer

Biopsy of the sentinel lymph node now forms part of routine management in many centres dealing with early stage breast cancer. This article seeks to discuss developments over the past number of years and to summarise current practice.

Internal mammary nodes in breast cancer: diagnosis and implications for patient management -- a systematic review

The management of internal mammary nodes (IMNs) in breast cancer is controversial. Surgical series from the 1950s showed that one third of breast cancer patients had IMN involvement, with a higher risk in patients with medial tumors and/or positive axillary nodes. IMN metastasis has similar prognostic importance as axillary nodal involvement. However, after three randomized trials showed no survival benefit from extended mastectomy compared with radical or modified radical mastectomy, IMN dissection was largely abandoned. Recently, lymphoscintigraphy studies have renewed interest in IMN evaluation. Approximately one fifth of internal mammary sentinel nodes are pathologic, although most centers do not perform IMN biopsies because of concerns about morbidity and lack of established survival benefit. In addition, results from randomized trials testing the value of postmastectomy irradiation and a meta-analysis of 78 randomized trials have provided high levels of evidence that local-regional tumor control is associated with long-term survival improvements. This benefit was limited to trials that used systemic therapy, which was not routinely administered in the earlier surgical studies, although the contribution from IMN treatment is unclear. IMN irradiation has also been shown to cause increased cardiac morbidity. Before mature results from current randomized trials assessing the benefit of IMN irradiation become available, lymphoscintigraphy may be used to help guide decisions regarding systemic and local-regional treatment. However, even in patients with visualized primary IMN drainage, the potential benefit of treatment should be balanced against the risk of added morbidity.

The value of radiotherapy on metastatic internal mammary nodes in breast cancer. Results on a large series

The 'regional nodal mapping', is a fundamental step to stage breast carcinoma. In addition to the axillary nodes status, the involvement of internal mammary nodes is an important prognostic factor. Six hundred and sixty-three patients with breast carcinoma, mainly in the inner quadrants, underwent a biopsy of internal mammary nodes. Positive internal mammary nodes were found in 68 out of 663 cases (10.3%) representing 27.2% of all cases with regional node metastases (250). When histologically proven metastases were detected, radiotherapy was administered to the internal mammary nodes chain. In 254 cases, the surgeon's exploration was guided by a gamma probe. Out of these cases, 28 (11.0%) showed metastatic involvement. Out of the other 409 cases, not radioguided, 40 showed positive nodes (9.8%). Patients with internal mammary metastases treated with radiotherapy and appropriate systemic treatment showed an excellent survival (95% at 5 years), a result which is in opposition to the previous experience, which stated that invasion of internal mammary nodes is an ominous prognostic sign. We assume that this excellent result is due to radiotherapy to internal mammary nodes and we propose that exploration of internal mammary nodes should be part of the staging process of carcinomas of the medial part of the breast.

Preoperative lymphatic mapping does not predict the number of axillary sentinel lymph nodes identified during surgery in breast cancer patients

Sentinel lymph node biopsy (SLNB) has become the standard of care in most centers for axillary staging in patients with early breast cancer. Multiple radioactive nodes are often identified at surgery. The finding of multiple sentinel lymph nodes (SLNs) has been shown to be associated with lower rates of false-negative results in the SLNB procedure, hence the importance of removing and examining all SLNs. Often preoperative lymphatic mapping (PLM) is performed prior to surgery. In this study we examined whether the exact number of SLNs identified during surgery can be accurately predicted by PLM. During the years 2001-2004, 155 patients underwent both PLM and a SLNB in our breast unit. During surgery, an attempt was made to remove all radioactive nodes. The number of axillary radioactive foci found on PLM was compared with the number of radioactive nodes identified during surgery. The average number of sentinel nodes harvested was 2.3 (range 1-9). The average number of radioactive foci identified on PLM was 1.8 (range 0-5). Of the 155 patients, the number of sentinel nodes retrieved in surgery was greater than that found in preoperative mapping in 65 patients (41.9%), equal to that found in preoperative mapping in 60 patients (38.7%), and less than that found in preoperative mapping in 30 patients (19.4%). Thus in most patients, the number of SLNs found on PLM did not reflect the number of SLNs found intraoperatively. Therefore, even when the number of nodes identified on PLM has been reached in surgery, a meticulous search for additional nodes should still be carried out. The number of hot spots in preoperative mapping should serve as a rough indicator of the smallest number of nodes the surgeon should attempt to resect, but not the exact number of nodes expected to be found.

Sentinel lymph node biopsy as the new standard of care in the surgical treatment for breast cancer

During the recent years, based on the results of validation studies, the sentinel lymph node biopsy has replaced routine axillary dissection as the new standard of care in early breast cancer. The technique represents a minimally invasive, highly accurate method for axillary staging, which could spare approximately 65-70% of patients unnecessary axillary dissection and its related morbidity. Several technical and clinical controversies have been raised during the development of this new technique; the authors review the most important issues, some questions have already been answered and others are still under debate. As far as the technical aspects are concerned, mapping techniques, appropriate surgical training, options for pathological examination of sentinel lymph nodes and the issue of nonaxillary sentinel lymph nodes are discussed. An update on clinical controversies demonstrates that factors such as large tumor size, palpable axillary nodes, multifocality and multicentricity, previous breast and axillary surgery, and pregnancy are no longer regarded as absolute contraindications for sentinel lymph node biopsy. Feasibility, accuracy and timing of sentinel lymph node biopsy in patients undergoing neoadjuvant chemotherapy remain unsolved issues, as well as the indication of the technique for some subgroups of in situ lesions. Finally, one of the most attractive open forums for debate will be discussed: whether or not completion of axillary dissection in the case of positive SLN is always required.

Prospective Randomized Clinical Trial Comparing Intradermal, Intraparenchymal, and Subareolar Injection Routes for Sentinel Lymph Node Mapping and Biopsy in Breast Cancer

BACKGROUND

Multiple injection routes, including intradermal (ID), intraparenchymal (IP), and subareolar (SA), are used for 99mTc-sulfur colloid administration for sentinel lymph node (SLN) mapping and biopsy in breast cancer. The aim of this study was to compare localization by ID, IP, and SA injection routes based on preoperative lymphoscintigraphy and intraoperative identification.

METHODS

Four hundred prospectively randomized breast cancers underwent SLN mapping and biopsy.

RESULTS

Preoperative lymphoscintigraphy demonstrated localization to the axilla in 126/133 (95%) ID, 82/132 (62%) IP, and 96/133 (72%) SA (P < 0.001 ID vs. IP and ID vs. SA; P = 0.081 IP vs. SA), with a mean duration of preoperative lymphoscintigraphy of 139 +/- 18 minutes. Mean time to first localization when localization was demonstrated on preoperative lymphoscintigraphy was 8 +/- 14 minutes for ID, 53 +/- 49 for IP, and 22 +/- 29 for SA (P < 0.001 ID vs. IP and ID vs. SA; P = 0.003 IP vs. SA). Intraoperative identification of a SLN at the time of SLN biopsy was successful in 133/133 (100%) ID, 121/134 (90%) IP, and 126/133 (95%) SA (P < 0.001 ID vs IP; P = 0.014 ID vs. SA; P = 0.168 IP vs. SA), with a mean time from injection of 99mTc-sulfur colloid to start of SLN biopsy of 288 +/- 71 minutes. Mean intraoperative time to harvest the first SLN was 9 +/- 4 minutes for ID, 13 +/- 6 for IP, and 12 +/- 6 for SA (P < 0.001 ID vs. IP and ID vs. SA; P = 0.410 IP vs. SA).

CONCLUSIONS

The ID injection route demonstrated a significantly greater frequency of localization, decreased time to first localization on preoperative lymphoscintigraphy, and decreased time to harvest the first SLN. This represents the first prospective randomized clinical trial to confirm superiority of the ID route for administration of 99mTc-sulfur colloid during SLN mapping and biopsy in breast cancer.

The sentinel node in breast cancer: an update

There has been rapid acceptance of sentinel lymph node biopsy into the management of breast cancer over the past 10 years. This article seeks to highlight the controversies and to summarise its current status.

Effect of lymphoscintigraphy drainage patterns on sentinel lymph node biopsy in patients with breast cancer

BACKGROUND

Sentinel lymph node (SLN) biopsy examination is an accepted method of staging breast cancer patients. SLN biopsy examination in patients with drainage to the internal mammary chain (IMC) nodes is controversial.

METHODS

A prospective study of SLN biopsy examination followed by axillary dissection was analyzed to determine how surgeons manage patients with IMC drainage and the rates of axillary SLN identification and positivity in these cases.

RESULTS

Lymphoscintigraphy was performed in 2196 (53.2%) of the 4131 patients in this study. IMC drainage was noted in 80 patients (3.6%). An axillary SLN was identified in 29 of the 40 patients with IMC drainage alone (72.5%). The rate of finding a positive axillary lymph node did not differ based on the lymphoscintigraphic pattern (P = .470).

CONCLUSIONS

Most surgeons do not perform IMC SLN biopsy procedures. Even when lymphoscintigraphy shows isolated drainage to IMC nodes, axillary SLNs usually are identified. Lymphoscintigraphy therefore has limited usefulness.