- Email: [email protected]
Impact of the American College of Surgeons Oncology Group Z0011 Criteria Applied to a Contemporary Patient Population
mastectomy.2 In their analysis, 26 986 women with node-positive breast cancer were studied. This included 11 248 women treated with mastectomy. As is the case in the study conducted by Milgrom and colleagues and the NCDB report, they noted declining rates of completion ALND over time, particularly for older patients with smaller tumors. At a median follow-up of 50 months, ALND did not improve survival or regional recurrence rates. In patients with micrometastases, there were no statistically significant differences in terms of ipsilateral regional events between those who underwent SLNB alone and those who underwent complete ALND. Patients with macrometastases (n ¼ 20 148) had a significantly lower risk of developing ipsilateral regional events after complete ALND than after SLNB alone (0.08% vs 0.2%; HR ¼ 0.30; P ¼ .02). Although this study reached statistical significance in its analysis of risk of regional recurrence according to the extent of axillary surgery, the absolute difference between these 2 groups was only 0.12%. Assuming that the surgical procedure was the sole explanation for this increase in regional recurrence, 834 women would need to be subjected to a completion ALND to avoid an axillary recurrence in 1 patient. In the aforementioned NCDB study, given the
0.2% difference in axillary recurrence rates for those having macrometastases, 500 ALNDs would need to be performed to avoid 1 axillary recurrence. Milgrom and colleagues offer insight into potential explanations for the low rates of axillary recurrence noted in these studies, including the ACOSOG Z0011 trial. As the entry criteria for ACOSOG Z0011 required the use of whole-breast radiation in the supine position, 1 hypothesis for low axillary recurrence rates is that the axilla was included within the breast tangents. Milgrom and colleagues’ findings challenge this position. Only 5% of those patients treated with TM received postmastectomy radiation therapy. Several of the same investigators also demonstrated that delivery of whole-breast radiation in the prone position does not affect axillary recurrence rates,3 further refuting the need to deliver radiation for those patients not having completion ALNDs. Is a randomized clinical trial necessary to allow observation of small-burden axillary disease in women treated with total mastectomy? Based on observed recurrence rates in this study and in the SEER and NCDB databases, a study designed to demonstrate non-inferiority would require a similar number of accruals to those seen in ACOSOG Z011.
Noting the historical challenges of accrual to Z0011, this would represent a difficult undertaking. Without randomized clinical trial data to support this position, abundant data, including the present series, point to a very low risk of axillary recurrence in this patient population.
Impact of the American College of Surgeons Oncology Group Z0011 Criteria Applied to a Contemporary Patient Population
Background.dThe American College of Surgeons Oncology Group (ACOSOG) Z0011 trial concluded that axillary lymph node dissection (ALND) may not be necessary for all patients with sentinel lymph node (SLN) metastasis undergoing breastconserving therapy (BCT). The aim of this study was to assess applicability of Z0011 results to our patient population
and determine what percentage may be affected by these results. Study Design.dPatients with clinical T1-2, N0 breast cancer, treated with surgery first between 1994 and 2009, who had 1 to 2 positive SLNs, were included in this study. KaplanMeier survival curves were calculated and log-rank used to compare overall survival (OS) and disease-free survival
Yi M, Kuerer HM, Mittendorf EA, et al (The Univ of Texas MD Anderson Cancer Ctr, Houston) J Am Coll Surg 216:105-113, 2013
254
Breast Diseases: A Year BookÒ Quarterly Vol 24 No 3 2013
D. J. Winchester, MD
References 1. Bilimoria KY, Bentrem DJ, Hansen NM, et al. Comparison of sentinel lymph node biopsy alone and completion axillary lymph node dissection for node-positive breast cancer. J Clin Oncol. 2009;27: 2946-2953. 2. Yi M, Giordano SH, MericBernstam F, et al. Trends in and outcomes from sentinel lymph node biopsy (SLNB) alone vs. SLNB with axillary lymph node dissection for node-positive breast cancer patients: experience from the SEER database. Ann Surg Oncol. 2010;17: 343-351. 3. Setton J, Cody H, Tan L, et al. Radiation field design and regional control in sentinel lymph nodepositive breast cancer patients with omission of axillary dissection. Cancer. 2012;118:1994-2003.
(DFS) for ALND vs SLN dissection (SLND) alone in 2 patient populations: patients undergoing BCT or total mastectomy (TM) and patients undergoing BCT only. Results.dOf 861 patients, 188 (21.8%) underwent SLND alone. Of 488 (56.7%) patients who underwent BCT, 125 (25.6%) had SLND alone. Of 412 patients undergoing TM, 67 (16.3%) had SLND alone. Patients undergoing ALND were significantly younger, had larger tumors, macrometastasis, and extranodal extension in both populations. Compared with the Z0011 cohort, our BCT patients had more T1 tumors (76.0% vs 69.3%, p ¼ 0.01) and more grade II to III tumors (87.3% vs 76.2%, p < 0.0001). After adjusting for T-stage, there were no significant differences in DFS and OS between patients undergoing SLND alone or ALND in both populations. Conclusions.dExamination of our breast cancer patients with Z0011 trial criteria suggests that almost 75% of SLN-positive patients would be candidates to avoid ALND if they undergo BCT. The ACOSOG Z0011 trial demonstrated no benefit in survival or local control for T1-2 patients with 1-2 positive SLNs undergoing breast conservation surgery (BCS) with SLN biopsy alone compared with those undergoing completion ALND.1,2 There has been concern that the patients enrolled in ACOSOG Z0011 were a selected, favorable subpopulation who may not have represented the general population of breast cancer patients. This retrospective, single-institution study by Yi and colleagues compared characteristics of node-positive patients treated with SLN biopsy alone by physician preference between 1994 and 2009 with both those undergoing ALND and those enrolled in ACOSOG Z0011. Additionally, Yi and colleagues reported the potential impact that the
ACOSOG Z0011 findings would have had if applied to their pre-ACOSOG Z0011 patient population. Of the 861 patients with SLN metastases detected by routine staining, 449 had BCT and 121 had SLN biopsy alone. Not surprisingly, patients treated with SLN biopsy alone were older, had smaller tumors, and were more likely than those who underwent BCT to have micrometastatic disease in the SLN (72% vs 24%). In fact, only 34 patients with macrometastases did not undergo ALND. Because of the lack of standardized criteria for avoiding ALND and the significant differences between groups, the study does not tell us much about outcomes; however, the overall patient population (which also included 449 patients who underwent mastectomy) was similar to that enrolled in ACOSOG Z0011, with no difference in the distribution of hormone receptors or lymphovascular invasion between groups. Patients in The University of Texas MD Anderson Cancer Center series were actually significantly more likely to have T1 tumors than were those in the ACOSOG Z0011 trial. As in ACOSOG Z0011, only 27% of MD Anderson patients who underwent ALND had additional positive nodes at completion dissection. In aggregate, these findings suggest that the patients enrolled in ACOSOG Z0011 were fairly representative of clinically node-negative women who are candidates for BCS. In this pre-ACOSOG Z0011 series, 78.2% of patients underwent ALND. Had ACOSOG Z0011 eligibility criteria been applied to the entire population (including mastectomy patients), the authors estimated that almost 75% of their SLN-positive patients could have been spared ALND. We recently reported our experience with a prospectively defined cohort of BCS patients meeting ACOSOG Z0011 eligibility criteria. Axillary dissection was performed for
metastases in 3 or more SLNs or gross extracapsular extension/matted nodes. No other selection criteria were used. In this series of 287 patients, 242 (84%) met the criteria for SLN biopsy alone, and 238 (83%) were treated without ALND. Patients requiring ALND did not differ from those undergoing SLN biopsy alone in median age (60 years vs 58 years), hormone receptor status, or nuclear grade, but they did have slightly larger tumors (2.2 cm vs 1.6 cm; P < .001).3 These findings confirm, in a prospective fashion, that the ACOSOG Z0011 findings are widely applicable. In contrast, we would caution against using this approach in patients with 3 or more involved SLNs or those undergoing mastectomy. Of the 412 patients in this study with positive SLNs treated with mastectomy, 67 (16%) had SLN biopsy only. This study is not alone in suggesting that surgeons are selectively avoiding ALND in some mastectomy patients;4 however, the contribution of tangent field irradiation, which is a standard part of BCT, to the high rates of local control seen in ACOSOG Z0011 is uncertain. In the absence of clinical trials demonstrating the safety of this approach, we continue to strongly recommend routine ALND in patients with positive SLNs undergoing mastectomy. L. Dengel, MD M. Morrow, MD
References 1. Giuliano AE, Hunt KK, Ballman KV, et al. Axillary dissection vs no axillary dissection in women with invasive breast cancer and sentinel node metastasis: a randomized clinical trial. JAMA. 2011;305:569-575. 2. Giuliano AE, McCall L, Beitsch P, et al. Locoregional recurrence after
Breast Diseases: A Year BookÒ Quarterly Vol 24 No 3 2013
255
eligibility criteria are applied in routine practice: results from a prospective series of consecutively treated patients. Presented at: Society of Surgical Oncology, 66th Annual Cancer Symposium, National Harbor, Maryland, March 6e9, 2013. Abstract 6. http://link.springer.com/ content/pdf/10.1245%2Fs10434-0132877-x.pdf. Accessed June 6, 2013.
sentinel lymph node dissection with or without axillary dissection in patients with sentinel lymph node metastases: the American College of Surgeons Oncology Group Z0011 randomized trial. Ann Surg. 2010; 252:426-432. 3. Dengel LT, Junqueira MJ, Van Zee KJ, et al. How often is axillary dissection avoided when Z11
American College of Surgeons Oncology Group (ACOSOG) Z0011: Impact on Surgeon Practice Patterns Caudle AS, Hunt KK, Tucker SL, et al (The Univ of Texas MD Anderson Cancer Ctr, Houston) Ann Surg Oncol 19:3144-3151, 2012
Introduction.dThe ACOSOG Z0011 trial has been described as practice-changing. The goal of this study was to determine the impact of the trial on surgeon practice patterns at our institution. Methods.dThis is a review of practice patterns comparing the year before release of Z0011 to the year after an institutional multidisciplinary meeting discussing the results. Patients meeting Z0011 inclusion criteria were identified. Clinicopathologic data were compared between the cohorts. Results.dThere were 658 patients with clinical T1-2 tumors planned for breast conservation: 335 in the preZ0011 cohort and 323 post-Z0011. Sixty-two (19%) patients were sentinel lymph node (SLN) positive in the preZ0011 group versus 42 (13%) postZ0011 (p ¼ 0.06). Before Z0011, 85% (53/62) of SLN-positive patients underwent axillary node dissection (ALND) versus 24% (10/42) after Z0011
256
(p < 0.001). After Z0011, surgeons were more likely to perform ALND on patients with larger tumors (2.2 vs. 1.5 cm, p ¼ 0.09), lobular histology (p ¼ 0.01), fewer SLNs (1 vs. 3, p ¼ 0.09), larger SLN metastasis size (4 vs. 2.5 mm, p ¼ 0.19), extranodal extension present (20 vs. 6%, p ¼ 0.16), or a higher probability of positive nonSLNs (p ¼ 0.03). Surgeons were less likely to perform intraoperative nodal assessment post-Z0011 (26 vs. 69%, p < 0.001) resulting in decreased median operative times for SLN-negative patients (79 vs. 92 min, p < 0.001). Conclusions.dSurgeons at our institution have implemented Z0011 results for the majority of patients; however, clinicopathologic factors still impact the decision to perform ALND. Z0011 results have significantly impacted practice by decreasing rates of ALND, use of intraoperative nodal evaluation, and operative times. The ACOSOG Z0011 was a multicenter, randomized controlled trial that has been referred to as “practice changing.”1,2 Implementation of the Z0011 findings into practice, however, has been variable. Some have concerns that the patients enrolled in Z0011 were highly selected and that the Z0011 findings are not applicable to the general population of women undergoing breast conservation therapy.
Breast Diseases: A Year BookÒ Quarterly Vol 24 No 3 2013
4. Breslin T, Hwang S, Mamet R, et al. Patterns of definitive axillary management in the era prior to reporting ACOSOG Z0011: comparison between NCCN Centers and hospitals in Michigan. Cancer Res. 2012;72. http://cancerres. aacrjournals.org/cgi/content/short/72/ 24_MeetingAbstracts/P1-01-13? rss¼1. Accessed June 6, 2013.
Contrarily, there are also reports that the Z0011 findings are being extrapolated and applied to patients excluded from the original trial.3,4 This retrospective, singleinstitution report evaluated how the ACOSOG Z0011 findings altered surgical decision making for patients meeting Z0011 criteria. Caudle and colleagues compared findings from a group of 335 patients treated in a single year prior to Z0011 with those from a group of 323 patients treated in a single year after Z0011 results were reported. Importantly, this study included only patients who met the criteria for enrollment in the Z0011 trial. Patients who underwent neoadjuvant chemotherapy, had tumors greater than 5 cm, had immunohistochemically detected metastasis, or were undergoing mastectomy were excluded. A multidisciplinary discussion was held at the authors’ institution following the publication of the Z0011 findings. It does not appear that a formal treatment protocol was developed. Surgeons and oncologists implemented the Z0011 findings based on their interpretation of the data and their institution’s conference. Overall, the patients in the preand post-Z0011 groups were similar. However, there were more patients in the pre-Z0011 group with a positive SLN. Routine nodal ultrasound and
0.2% difference in axillary recurrence rates for those having macrometastases, 500 ALNDs would need to be performed to avoid 1 axillary recurrence. Milgrom and colleagues offer insight into potential explanations for the low rates of axillary recurrence noted in these studies, including the ACOSOG Z0011 trial. As the entry criteria for ACOSOG Z0011 required the use of whole-breast radiation in the supine position, 1 hypothesis for low axillary recurrence rates is that the axilla was included within the breast tangents. Milgrom and colleagues’ findings challenge this position. Only 5% of those patients treated with TM received postmastectomy radiation therapy. Several of the same investigators also demonstrated that delivery of whole-breast radiation in the prone position does not affect axillary recurrence rates,3 further refuting the need to deliver radiation for those patients not having completion ALNDs. Is a randomized clinical trial necessary to allow observation of small-burden axillary disease in women treated with total mastectomy? Based on observed recurrence rates in this study and in the SEER and NCDB databases, a study designed to demonstrate non-inferiority would require a similar number of accruals to those seen in ACOSOG Z011.
Noting the historical challenges of accrual to Z0011, this would represent a difficult undertaking. Without randomized clinical trial data to support this position, abundant data, including the present series, point to a very low risk of axillary recurrence in this patient population.
Impact of the American College of Surgeons Oncology Group Z0011 Criteria Applied to a Contemporary Patient Population
Background.dThe American College of Surgeons Oncology Group (ACOSOG) Z0011 trial concluded that axillary lymph node dissection (ALND) may not be necessary for all patients with sentinel lymph node (SLN) metastasis undergoing breastconserving therapy (BCT). The aim of this study was to assess applicability of Z0011 results to our patient population
and determine what percentage may be affected by these results. Study Design.dPatients with clinical T1-2, N0 breast cancer, treated with surgery first between 1994 and 2009, who had 1 to 2 positive SLNs, were included in this study. KaplanMeier survival curves were calculated and log-rank used to compare overall survival (OS) and disease-free survival
Yi M, Kuerer HM, Mittendorf EA, et al (The Univ of Texas MD Anderson Cancer Ctr, Houston) J Am Coll Surg 216:105-113, 2013
254
Breast Diseases: A Year BookÒ Quarterly Vol 24 No 3 2013
D. J. Winchester, MD
References 1. Bilimoria KY, Bentrem DJ, Hansen NM, et al. Comparison of sentinel lymph node biopsy alone and completion axillary lymph node dissection for node-positive breast cancer. J Clin Oncol. 2009;27: 2946-2953. 2. Yi M, Giordano SH, MericBernstam F, et al. Trends in and outcomes from sentinel lymph node biopsy (SLNB) alone vs. SLNB with axillary lymph node dissection for node-positive breast cancer patients: experience from the SEER database. Ann Surg Oncol. 2010;17: 343-351. 3. Setton J, Cody H, Tan L, et al. Radiation field design and regional control in sentinel lymph nodepositive breast cancer patients with omission of axillary dissection. Cancer. 2012;118:1994-2003.
(DFS) for ALND vs SLN dissection (SLND) alone in 2 patient populations: patients undergoing BCT or total mastectomy (TM) and patients undergoing BCT only. Results.dOf 861 patients, 188 (21.8%) underwent SLND alone. Of 488 (56.7%) patients who underwent BCT, 125 (25.6%) had SLND alone. Of 412 patients undergoing TM, 67 (16.3%) had SLND alone. Patients undergoing ALND were significantly younger, had larger tumors, macrometastasis, and extranodal extension in both populations. Compared with the Z0011 cohort, our BCT patients had more T1 tumors (76.0% vs 69.3%, p ¼ 0.01) and more grade II to III tumors (87.3% vs 76.2%, p < 0.0001). After adjusting for T-stage, there were no significant differences in DFS and OS between patients undergoing SLND alone or ALND in both populations. Conclusions.dExamination of our breast cancer patients with Z0011 trial criteria suggests that almost 75% of SLN-positive patients would be candidates to avoid ALND if they undergo BCT. The ACOSOG Z0011 trial demonstrated no benefit in survival or local control for T1-2 patients with 1-2 positive SLNs undergoing breast conservation surgery (BCS) with SLN biopsy alone compared with those undergoing completion ALND.1,2 There has been concern that the patients enrolled in ACOSOG Z0011 were a selected, favorable subpopulation who may not have represented the general population of breast cancer patients. This retrospective, single-institution study by Yi and colleagues compared characteristics of node-positive patients treated with SLN biopsy alone by physician preference between 1994 and 2009 with both those undergoing ALND and those enrolled in ACOSOG Z0011. Additionally, Yi and colleagues reported the potential impact that the
ACOSOG Z0011 findings would have had if applied to their pre-ACOSOG Z0011 patient population. Of the 861 patients with SLN metastases detected by routine staining, 449 had BCT and 121 had SLN biopsy alone. Not surprisingly, patients treated with SLN biopsy alone were older, had smaller tumors, and were more likely than those who underwent BCT to have micrometastatic disease in the SLN (72% vs 24%). In fact, only 34 patients with macrometastases did not undergo ALND. Because of the lack of standardized criteria for avoiding ALND and the significant differences between groups, the study does not tell us much about outcomes; however, the overall patient population (which also included 449 patients who underwent mastectomy) was similar to that enrolled in ACOSOG Z0011, with no difference in the distribution of hormone receptors or lymphovascular invasion between groups. Patients in The University of Texas MD Anderson Cancer Center series were actually significantly more likely to have T1 tumors than were those in the ACOSOG Z0011 trial. As in ACOSOG Z0011, only 27% of MD Anderson patients who underwent ALND had additional positive nodes at completion dissection. In aggregate, these findings suggest that the patients enrolled in ACOSOG Z0011 were fairly representative of clinically node-negative women who are candidates for BCS. In this pre-ACOSOG Z0011 series, 78.2% of patients underwent ALND. Had ACOSOG Z0011 eligibility criteria been applied to the entire population (including mastectomy patients), the authors estimated that almost 75% of their SLN-positive patients could have been spared ALND. We recently reported our experience with a prospectively defined cohort of BCS patients meeting ACOSOG Z0011 eligibility criteria. Axillary dissection was performed for
metastases in 3 or more SLNs or gross extracapsular extension/matted nodes. No other selection criteria were used. In this series of 287 patients, 242 (84%) met the criteria for SLN biopsy alone, and 238 (83%) were treated without ALND. Patients requiring ALND did not differ from those undergoing SLN biopsy alone in median age (60 years vs 58 years), hormone receptor status, or nuclear grade, but they did have slightly larger tumors (2.2 cm vs 1.6 cm; P < .001).3 These findings confirm, in a prospective fashion, that the ACOSOG Z0011 findings are widely applicable. In contrast, we would caution against using this approach in patients with 3 or more involved SLNs or those undergoing mastectomy. Of the 412 patients in this study with positive SLNs treated with mastectomy, 67 (16%) had SLN biopsy only. This study is not alone in suggesting that surgeons are selectively avoiding ALND in some mastectomy patients;4 however, the contribution of tangent field irradiation, which is a standard part of BCT, to the high rates of local control seen in ACOSOG Z0011 is uncertain. In the absence of clinical trials demonstrating the safety of this approach, we continue to strongly recommend routine ALND in patients with positive SLNs undergoing mastectomy. L. Dengel, MD M. Morrow, MD
References 1. Giuliano AE, Hunt KK, Ballman KV, et al. Axillary dissection vs no axillary dissection in women with invasive breast cancer and sentinel node metastasis: a randomized clinical trial. JAMA. 2011;305:569-575. 2. Giuliano AE, McCall L, Beitsch P, et al. Locoregional recurrence after
Breast Diseases: A Year BookÒ Quarterly Vol 24 No 3 2013
255
eligibility criteria are applied in routine practice: results from a prospective series of consecutively treated patients. Presented at: Society of Surgical Oncology, 66th Annual Cancer Symposium, National Harbor, Maryland, March 6e9, 2013. Abstract 6. http://link.springer.com/ content/pdf/10.1245%2Fs10434-0132877-x.pdf. Accessed June 6, 2013.
sentinel lymph node dissection with or without axillary dissection in patients with sentinel lymph node metastases: the American College of Surgeons Oncology Group Z0011 randomized trial. Ann Surg. 2010; 252:426-432. 3. Dengel LT, Junqueira MJ, Van Zee KJ, et al. How often is axillary dissection avoided when Z11
American College of Surgeons Oncology Group (ACOSOG) Z0011: Impact on Surgeon Practice Patterns Caudle AS, Hunt KK, Tucker SL, et al (The Univ of Texas MD Anderson Cancer Ctr, Houston) Ann Surg Oncol 19:3144-3151, 2012
Introduction.dThe ACOSOG Z0011 trial has been described as practice-changing. The goal of this study was to determine the impact of the trial on surgeon practice patterns at our institution. Methods.dThis is a review of practice patterns comparing the year before release of Z0011 to the year after an institutional multidisciplinary meeting discussing the results. Patients meeting Z0011 inclusion criteria were identified. Clinicopathologic data were compared between the cohorts. Results.dThere were 658 patients with clinical T1-2 tumors planned for breast conservation: 335 in the preZ0011 cohort and 323 post-Z0011. Sixty-two (19%) patients were sentinel lymph node (SLN) positive in the preZ0011 group versus 42 (13%) postZ0011 (p ¼ 0.06). Before Z0011, 85% (53/62) of SLN-positive patients underwent axillary node dissection (ALND) versus 24% (10/42) after Z0011
256
(p < 0.001). After Z0011, surgeons were more likely to perform ALND on patients with larger tumors (2.2 vs. 1.5 cm, p ¼ 0.09), lobular histology (p ¼ 0.01), fewer SLNs (1 vs. 3, p ¼ 0.09), larger SLN metastasis size (4 vs. 2.5 mm, p ¼ 0.19), extranodal extension present (20 vs. 6%, p ¼ 0.16), or a higher probability of positive nonSLNs (p ¼ 0.03). Surgeons were less likely to perform intraoperative nodal assessment post-Z0011 (26 vs. 69%, p < 0.001) resulting in decreased median operative times for SLN-negative patients (79 vs. 92 min, p < 0.001). Conclusions.dSurgeons at our institution have implemented Z0011 results for the majority of patients; however, clinicopathologic factors still impact the decision to perform ALND. Z0011 results have significantly impacted practice by decreasing rates of ALND, use of intraoperative nodal evaluation, and operative times. The ACOSOG Z0011 was a multicenter, randomized controlled trial that has been referred to as “practice changing.”1,2 Implementation of the Z0011 findings into practice, however, has been variable. Some have concerns that the patients enrolled in Z0011 were highly selected and that the Z0011 findings are not applicable to the general population of women undergoing breast conservation therapy.
Breast Diseases: A Year BookÒ Quarterly Vol 24 No 3 2013
4. Breslin T, Hwang S, Mamet R, et al. Patterns of definitive axillary management in the era prior to reporting ACOSOG Z0011: comparison between NCCN Centers and hospitals in Michigan. Cancer Res. 2012;72. http://cancerres. aacrjournals.org/cgi/content/short/72/ 24_MeetingAbstracts/P1-01-13? rss¼1. Accessed June 6, 2013.
Contrarily, there are also reports that the Z0011 findings are being extrapolated and applied to patients excluded from the original trial.3,4 This retrospective, singleinstitution report evaluated how the ACOSOG Z0011 findings altered surgical decision making for patients meeting Z0011 criteria. Caudle and colleagues compared findings from a group of 335 patients treated in a single year prior to Z0011 with those from a group of 323 patients treated in a single year after Z0011 results were reported. Importantly, this study included only patients who met the criteria for enrollment in the Z0011 trial. Patients who underwent neoadjuvant chemotherapy, had tumors greater than 5 cm, had immunohistochemically detected metastasis, or were undergoing mastectomy were excluded. A multidisciplinary discussion was held at the authors’ institution following the publication of the Z0011 findings. It does not appear that a formal treatment protocol was developed. Surgeons and oncologists implemented the Z0011 findings based on their interpretation of the data and their institution’s conference. Overall, the patients in the preand post-Z0011 groups were similar. However, there were more patients in the pre-Z0011 group with a positive SLN. Routine nodal ultrasound and