Ann Surg Oncol DOI 10.1245/s10434-014-4269-2
ORIGINAL ARTICLE – BREAST ONCOLOGY
Clinical Significance of Extracapsular Invasion at Sentinel Lymph Nodes in Breast Cancer Patients with Sentinel Lymph Node Involvement Hideo Shigematsu, MD, PhD1, Kenichi Taguchi, MD, PhD2, Hiroko Koui, MD3, and Shinji Ohno, MD, PhD3 1
Department of Surgical Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan; 2Department of Pathology, National Kyushu Cancer Center, Fukuoka, Japan; 3Department of Breast Oncology, National Kyushu Cancer Center, Fukuoka, Japan
ABSTRACT Background. A certain number of patients have extracapsular invasion (ECI) at the sentinel lymph node (SLN), but only a few reports describe its clinical significance. This study aimed to determine the clinical significance of ECI at SLN in breast cancer patients with involved SLN. Methods. This study evaluated ECI at SLN in 131 consecutive SLN-positive patients who underwent axillary lymph node dissection between 2003 and 2008 at the National Kyushu Cancer Center with regard to their longterm prognosis and non-SLN metastasis. Results. Of the 131 patients, 46 (35 %) tested positive for ECI at SLN. Of these 46 patients, 61 % (28/46) had nonSLN metastasis compared with 28 % (24/85) in ECI-negative group (v2 test; P \ 0.001). Multivariate analysis showed that ECI at SLN is significantly predictive for nonSLN metastasis [hazard ratio (HR) 3.2; 95 % confidence interval (CI) 1.4–7.1; P = 0.005]. The 5-year recurrencefree survival (RFS) rates were 71.3 % in the ECI-positive group and 89.9 %in the ECI-negative group (P = 0.001, log-rank test). Cox-regression analysis showed that ECI at SLN independently predicts lower RFS (HR 4.5; 95 % CI 1.8–11.7; P = 0.002). Conclusions. The findings show that ECI at SLN is an independent predictor of both non-SLN metastasis and poor prognosis for breast cancer patients with involved
Ó Society of Surgical Oncology 2014 First Received: 19 July 2014 H. Shigematsu, MD, PhD e-mail: [email protected]
SLN. The clinical significance of ECI at SLN in operablestage breast cancer warrants further study.
Axillary lymph node dissection (ALND) had been the standard care in the management of operable breast cancer for local disease control and precise axillary staging. However, ALND is associated with unfavorable complications including arm pain, numbness, and lymphedema.1–4 To avoid the comorbidity of ALND, sentinel lymph node (SLN) biopsy was developed for patients with clinically node-negative operable breast cancer. Because large clinical trials have shown that SLN biopsy gives an equivalent prognosis and less arm morbidity than ALND for SLNnegative patients,5–7 ALND is strongly discouraged for SLN-negative patients, but has remained a standard procedure for SLN-positive patients because approximately 40 % of them were estimated to have non-SLN metastasis.8 However, in a recent prospective randomized study, omitting ALND did not affect local control or prognosis for SLN-positive patients.9 The Z0011 trial found that omitting ALND did not lead to inferior survival or local control in SLN-positive patients if they met the following criteria: favorable low T stage, no more than two involved SLNs, and no gross extracapsular extension in the involved nodes. To reflect these results, updated American Society of Clinical Oncology Clinical Practice Guidelines state that women who meet the Z0011 criteria should not undergo ALND.10 Thus, more breast cancer patients currently omit ALND irrespective of SLN involvement.11,12 Axillary lymph node status, including invasive behavior and size of metastases, is important in estimating recurrence risk and selecting adjuvant therapy for patients with operable breast cancer. Larger SLN metastases are a well-established
H. Shigematsu et al.
prediction of non-SLN metastasis and are associated with an impaired long-term prognosis.13 Extracapsular invasion (ECI) at SLN is found in some patients with operable breast cancer and reportedly is associated with non-SLN metastasis.14,15 A large cohort study confirmed that the presence and extent of ECI at SLN were significantly correlated with non-SLN metastasis and number of involved lymph nodes.16 Additionally, ECI at the dissected lymph node is reportedly associated with a poor prognosis for operable breast cancer patients.17,18 However, because the reported studies were not intended for patients who underwent SLN biopsies, the prognostic significance of ECI at SLN still is uncertain. Considering that fewer patients with involved SLN undergo ALND, the prognostic value of ECI at SLN should be evaluated in detail. We therefore evaluated the clinical significance of ECI at SLN in breast cancer patients, including its association with non-SLN metastasis and long-term survival. PATIENTS AND METHODS
SLN involvement was recognized in these sections despite negative results of frozen section analysis, additional ALND was performed at the patient’s and physician’s choice. NonSLNs were evaluated by routine H&E staining. During the study period, 1,031 SLN biopsies were performed for invasive breast cancer, and 131 patients (12.7 %) underwent additional axillary lymph node dissection for SLN involvement. This study evaluated ECI at SLN in terms of its association with long-term prognosis and non-SLN involvement in the 131 patients. For 11 patients, additional ALND was omitted irrespective of SLN involvement due to a negative result of a frozen-section analysis or because of their comorbidities. Three patients tested positive for ECI at SLN, and eight patients tested negative for ECI at SLN. Adjuvant chemotherapy was administered to two patients with ECI at SLN and to four patients without ECI at SLN. None of these patients experienced breast cancer recurrence, and they were excluded from this study.
This study was approved by National Kyushu Cancer Center review board, which waived the requirement for informed consent from individual patients because this study was a retrospective review of a patient database. We retrospectively reviewed the data of patients with invasive breast cancer who underwent SLN biopsy at National Kyushu Cancer Center between 2003 and 2008 and obtained clinicopathologic data from our prospectively maintained institutional database of breast cancer patients who underwent surgery for operable stage breast cancer. We performed SLN biopsies for patients with clinically node-negative breast cancer (cN0). At our institution, cN0 was determined by palpation and imaging including ultrasonography and computed tomography (CT). Fine-needle aspiration or core needle biopsy was performed for suspicious lymph nodes to confirm the presence of metastasis. The SLN biopsy was performed using a subareolar injection of blue dye and 99mTc-labeled sulfur colloid at the same time as the primary breast tumor resection. The study identified SLNs as nodes that demonstrated blue dye uptake, radiotracer uptake, or both. During surgery, frozen-section analysis of SLN was performed for all the patients. A maximal sectioned surface was evaluated with a microtome setting of 4 lm and hematoxylin and eosin (H&E) staining. If metastasis was recognized in frozen-section analysis, additional ALND was essentially performed during the operation. For definitive pathologic diagnosis, each SLN was serially sectioned along the short axis at 2-mm intervals, and the sections were fixed in formalin, embedded in paraffin, and examined using H&E staining. If
The clinicopathologic variables included age, pathologic size of the primary tumor, histologic grade, lymphovascular invasion, estrogen receptor (ER) expression, progesterone receptor (PgR), human epidermal growth factor receptor 2 (HER2) status, number of SLNs resected, size of SLN metastases, number of SLN metastases, and presence of ECI at involved SLN. Both ER and PgR assays were performed using immunohistochemistry (IHC) analysis; 10 % greater than staining of the cells was considered positive. Estimation of HER2 status was performed by either IHC or fluorescence in situ hybridization (FISH) at diagnosis. Most variables came from a prospectively maintained database. However, the size of SLN metastases and the presence of ECI were retrospectively reviewed on archived H&E stained sections of involved SLN by a pathologist (K.T.) with no information on clinical outcome. Sentinel lymph node metastasis size was defined as the maximum size of all involved SLNs. Extracapsular invasion was defined as positive if extracapsular tumor growth was present in an involved SLN section (Fig. 1). Adjuvant therapy was administered in accordance with clinical guidelines and the patient’s direction. Patients with ER- or PgR-positive breast cancer essentially received adjuvant endocrine therapy. The decision to use adjuvant chemotherapy was based on pathologic tumor and node stage, hormone receptor expression, HER2 status, malignancy, and proliferation markers. At the time of surgery, ECI at the involved SLN was not routinely evaluated and not considered in the decision to use systemic therapy.
Clinical Significance of ECI at SLN
FIG. 1 Typical histological examples of presence of extracapsular invasion (ECI) at involved sentinel lymph node (SLN); the tumor cells invade through the capsule of the lymph node, and extend into perinodal adipose tissue
Study End Points This study aimed to determine whether ECI at involved SLN sections was associated with non-SLN metastases and long-term prognosis. After curative surgery for primary breast cancer, patients were assessed for disease recurrence in accordance with standard clinical practice. Recurrencefree survival (RFS) was defined as the elapsed time from the date of surgery until the first event (relapse or death from any cause) or last follow-up visit. The diagnosis of recurrent disease was confirmed by physical examination, imaging methods, or both. A biopsy showing metastasis was not essential for the diagnosis of recurrent disease. Overall survival (OS) was defined as the time from surgery until death due to any cause.
(35 %) tested positive for ECI at SLN. Most patients had a limited number of involved SLNs (numbers of involved SLN 1/2/3/4 were respectively 89/33/8/1). The patients with ECI at SLN had a significantly higher probability of a larger N stage, larger SLN metastases, presence of nonSLN metastasis, and breast cancer recurrence than the patients without ECI at SLN. The ECI-positive group tended to have a higher probability of death than the ECInegative group. The presence of ECI at SLN was not associated with histologic grade, ER, PgR, HER2, or lymphovascular invasion. The frequency of adjuvant chemotherapy treatments was not associated with the presence of ECI at SLN (Table 1). Extracapsular Invasion at SLN and Non-SLN Metastasis
Statistical Analysis Associations between ECI and clinicopathologic parameters were analyzed using the v2 test. Logistic regression analysis was used to evaluate relationships between ECI and non-SLN involvement in a multivariate model. Durations of RFS and OS were analyzed using the Kaplan–Meier method. Differences in RFS and OS were assessed using the log-rank test. Cox regression analysis was used to evaluate relationships between ECI at SN and prognosis in a multivariate model. All tests were two-sided. Hazard ratios (95 %confidence intervals [CIs]) and P values are reported. Statistical analyses were carried out using SPSS software (version 11 for Windows; SAS Institute, Tokyo, Japan). RESULTS Extracapsular Invasion at SLN and Clinicopathologic Features Of the 131 patients with primary invasive breast cancer who underwent additional ALND for SLN involvement, 46
Of the 46 ECIs in SLN-positive patients, 28 (61 %) were found to have additional non-SLN metastasis compared with 24 (28 %) of the 85 ECIs in SLN-negative patients. The odds ratio of the ECI-positive group for non-SLN metastasis was 4.0 compared with the ECI-negative group (P \ 0.001, v2 test). For predicting non-SLN metastases, ECI at SLN had a specificity of 77 % and a sensitivity of 54 %. The positive and negative predictive values were respectively 61 and 72 %. In the univariate analysis, size of SLN metastasis (\2 vs. C2 mm), number of SLN metastases (C2 vs. 1), and ECI at SLN (yes vs no) were significantly associated with the presence of additional non-SLN metastases (Table 2). Tumor size, lymphovascular invasion, histologic grade, ER, PgR, HER2 status, and number of resected SLN were not associated with non-SLN involvement. In the multivariate analysis, ECI at SLN was significantly associated with non-SLN metastasis after other predictive factors had been accounted for, including size of SLN metastasis and number of SLN metastasis (yes vs. no: HR 3.2; 95 % CI 1.4–7.1; P = 0.005) (Table 2). The
H. Shigematsu et al. TABLE 1 Association between extracapsular invasion at the sentinel lymph node and clinicopathologic factors
TABLE 2 Incidence of positive non-SLN in relation to clinicopathologic factors in uni- and multivariate analyses
Total Extracapsular invasion (n = 131) n (%) Negative (n = 85)
Median age: years (range)
52 (32– 80)
Pathologic tumor size (cm) C2 71 \2
Positive (n = 46)
52 (32–73) 52 (36–80)
Size of SLN metastasis (mm) C2 \2
\2 1.7 Histologic grade 1, 2
Positive 1.6 0.6–4.6 No. of SLNs resected
Lymphovascular invasion Negative
Histologic grade 1,2
Pathologic tumor size (cm)
Pathologic N stage 1
Size of SLN metastasis (mm) C2
No. of SLN metastases 1
Extracapusula invasion in SLN 41 90
34 (83) 51 (57)
7 (17) 39 (43)
No. of SLN biopsies
Presence of non-SLN metastasis \0.001
Adjuvant chemotherapy 0.28
N nodal, ER estrogen receptor, PgR progesteron receptor, HER2 human epidermal growth factor receptor 2, SLN sentinel lymph node
number of resected SLNs also was significantly associated with non-SLN metastasis (C2 vs. 1: HR 2.6; 95 % CI 1.1–5.9; P = 0.03) (Table 2).
SLN sentinel lymph node, HR hazard ratio, CI confidence interval, ER estrogen receptor, PgR progesteron receptor, HER2 human epidermal growth factor receptor 2
Extracapsular Invasion at SLN and Prognosis The median follow-up period was 6.1 years (range 0.4– 10.1 years). There were 24 breast cancer recurrences, and 12 patients died during this follow-up period. Figure 2 shows Kaplan–Meier curves of RFS for the presence of extracapsula invasion. The log-rank test showed that ECI at SLN was significantly correlated with worse breast cancer RFS (P = 0.001). The 5-year RFS rates were 89.9 % (95 % CI 86.5–93.3 %) in the ECI-negative group and 71.3 % (95 % CI 64.3–78.3 %) in the ECI-positive group. The univariate analysis of RFS for all the patients included the following variables: pathologic T- and
Clinical Significance of ECI at SLN
Proportion of relapse free survival
ECI negative ECI positive
Log rank test P = 0.001
censored 0.0 0.0
Years from operation Number at risk ECI negative
FIG. 2 Presence of extracapsula invasion and relapse free survival
N-stage, histologic grade, presence of lymphovascular invasion, ER, PgR and HER2, size of SLN metastasis, presence of ECI at SLN, and administration of adjuvant chemotherapy (Table 3). Histologic grade, ECI at SLN, and adjuvant chemotherapy were significant prognostic factors. The multivariate analysis showed that ECI at SLN was an independent predictor of RFS (HR 4.5; 95 % CI 1.8– 11.7; P = 0.002). Higher histologic grade, HER2 positivity, and omission of adjuvant chemotherapy also were significantly associated with poor prognosis. With regard to OS, 7 patients (15 %) died in the ECI-positive group, and 5 patients (6 %) died in the ECI-negative group. The log-rank test showed a marginally significant association between ECI at SLN and worse OS (P = 0.049). Cox regression analysis also showed that ECI at SLN was a marginal independent prognostic factor for OS (HR 3.7; 95 % CI 1.1–13.0, P = 0.04).
DISCUSSION In this retrospective analysis of 131 consecutive patients with breast cancer who underwent ALND for SLN involvement, 46 patients (35 %) were determined to be ECI at SLN positive, and ECI at SLN was shown to be predictor of both non-SLN metastasis and poor prognosis in early-stage breast cancer. For operable breast cancer patients, selection of adjuvant therapy is based on the risk for disease recurrence and prediction of response to systemic therapy. The established prognostic and predictive factors are pathologic tumor and node stage and biologic markers including hormone receptor expression, HER2 status, malignancy, and proliferation markers.4,19–21 In addition to these conventional
factors, several novel procedures have been investigated. Multiple gene expression assays have been shown to provide additional prognostic and predictive information.22–24 As morphologic imaging, 18F-fluoro-2-deoxyglucose (FDG)-PET/CT reportedly provides information on breast cancer aggressiveness and prognosis.25,26 Although these novel methods are interesting and potentially useful, they also are too costly and nonstandardized to be practical for clinical practice,27,28 whereas ECI at the involved lymph node can be readily evaluated and interpreted by pathologists and clinicians on routine H&E stained sections. Extracapsular invasion at the involved lymph node can be regarded as a demonstration of tumor migration and invasion ability. Previous studies have demonstrated that the presence of ECI at involved axillary nodes is associated with poor prognosis and total number of involved axillary nodes in patients with breast cancer.17,18,29,30 However, the prognostic significance of ECI at SLN in patients with operable breast cancer has not been investigated, and the prognostic value of ECI at SLN has not been previously assessed. This study showed several clinical associations of ECI at SLN in breast cancer patients with involved SLN. First, the presence of ECI at SLN was shown to be an independent predictor of poor prognosis. Patients with ECI at SLN had significantly worse recurrence-free survival than patients without ECI at SLN. Additionally, patients with ECI at SLN tended to have shorter OS. Because ECI at SLN had no relationship with other predictors of poor prognosis, including ER-negativity, lymphovascular invasion, high grade, and tumor size, ECI at SLN can be regarded as an independent prognostic factor. Second, the presence of ECI at SLN was a strong predictor of non-SLN metastasis. Our finding is consistent with previous findings, so ECI at SLN can be regarded as an established predictive marker for non-SLN metastasis.14–16,31 In this study, 81 patients met the Z0011 criteria including T1–2 stage, 1–2? SLN, and reception of breastconserving surgery. Among these patients, 25 (31 %) were determined to be positive for ECI at SLN, and non-SLN involvement was seen more frequently in the ECI-positive group (13/25, 52 %) than in the ECI-negative group (16/56, 27 %). Thus, ECI at SLN is still a significant predictor of non-SLN involvement in patients with small tumor burdens. Considering these results, breast cancer patients with ECI at SLN are recommended to receive substantial systemic therapy and additional axillary treatment. Finally, some clinically node-negative breast cancer patients (35 %) were positive for ECI at SLN on archived H&E section of involved SLN. The rate of ECI at SLN in this study was compatible with that of previous reports in which the ECI at SLN was also evaluated on routine H&E stained section, and the rate of ECI at SLN ranged from 19
H. Shigematsu et al. TABLE 3 Uni- and multivariate analyses of disease-free survival Characteristics
Univariate analysis HR
Pathologic tumor size (cm) C2
Pathologic N stage 1
Histologic grade 1, 2 3
Lymphovascular invasion Negative
Size of SLN metastasis Micro Macro
Extracapusular invasion in SLN No
Adjuvant chemotherapy Yes
HR hazard ratio, CI confidence interval, N nodal, ER estrogen receptor, PgR progesteron receptor, HER2 human epidermal growth factor receptor 2, SLN sentinel lymph node
to 45 %.15,16,32,33 Considering feasibility, reproducibility, and availability, ECI at SLN can be evaluated in routine practice. According to these findings, ECI at SLN has significant clinical meaning and should be evaluated in the clinical setting. Our study had several limitations. It was a single-institution retrospective analysis of relatively few samples. Further examination with a larger number of cases in a prospectively designed trial is warranted. The patients described in current report may have had a lower rate of SLN involvement than those in previous reports. Preoperative axillary lymph node staging at our institution was essentially performed by physical examination, ultrasonography, CT, and MRI. Suspicious lymph nodes were further examined
with fine-needle aspiration biopsy or needle biopsy to detect metastasis. These procedures may have reduced the rate of SLN-involvement. In conclusion, this study showed that ECI at SLN can independently predict both poor prognosis and non-SLN metastasis. Considering that according to the results of the Z0011 trial, fewer breast cancer patients with involved SLN undergo ALND, understanding of the involved SLN can optimize selection of adjuvant and other therapies. The clinical significance of ECI at SLN in operable stage breast cancer warrants further study. DISCLOSURE interests.
The authors declare that they have no competing
Clinical Significance of ECI at SLN
REFERENCES 1. Fisher B, Redmond C, Fisher ER, et al. Ten-year results of a randomized clinical trial comparing radical mastectomy and total mastectomy with or without radiation. N Engl J Med. 1985;312:674–81. 2. Fisher B, Jeong JH, Anderson S, Bryant J, Fisher ER, Wolmark N. Twenty-five-year follow-up of a randomized trial comparing radical mastectomy, total mastectomy, and total mastectomy followed by irradiation. N Engl J Med. 2002;347:567–75. 3. Sanghani M, Balk EM, Cady B. Impact of axillary lymph node dissection on breast cancer outcome in clinically node negative patients: a systematic review and meta-analysis. Cancer. 2009;115:1613–20. 4. Singletary SE, Allred C, Ashley P, et al. Revision of the American Joint Committee on Cancer staging system for breast cancer. J Clin Oncol. 2002;20:3628–36. 5. Lucci A, McCall LM, Beitsch PD, et al. Surgical complications associated with sentinel lymph node dissection (SLND) plus axillary lymph node dissection compared with SLND alone in the American College of Surgeons Oncology Group Trial Z0011. J Clin Oncol. 2007;25:3657–63. 6. Krag DN, Anderson SJ, Julian TB, et al. Sentinel-lymph-node resection compared with conventional axillary-lymph-node dissection in clinically node-negative patients with breast cancer: overall survival findings from the NSABP B-32 randomised phase 3 trial. Lancet Oncol. 2010;11:927–33. 7. Kapoor NS, Sim MS, Lin J, Giuliano AE. Long-term outcome of patients managed with sentinel lymph node biopsy alone for node-negative invasive breast cancer. Arch Surg. 2012;147:1047– 52. 8. Werkoff G, Lambaudie E, Fondrinier E, et al. Prospective multicenter comparison of models to predict four or more involved axillary lymph nodes in patients with breast cancer with one to three metastatic sentinel lymph nodes. J Clin Oncol. 2009;27:5707–12. 9. 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;305:569–75. 10. Lyman GH, Temin S, Edge SB, et al. Sentinel lymph node biopsy for patients with early-stage breast cancer: American Society of Clinical Oncology clinical practice guideline update. J Clin Oncol. 2014;32:1365–83. 11. Chen AY, Halpern MT, Schrag NM, Stewart A, Leitch M, Ward E. Disparities and trends in sentinel lymph node biopsy among early-stage breast cancer patients (1998–2005). J Natl Cancer Inst. 2008;100:462–74. 12. Heneghan HM, Prichard RS, Devaney A, et al. Evolution of breast cancer management in Ireland: a decade of change. BMC Surg. 2009;9:15. 13. Weaver DL, Ashikaga T, Krag DN, et al. Effect of occult metastases on survival in node-negative breast cancer. N Engl J Med. 2011;364:412–21. 14. Fujii T, Yanagita Y, Fujisawa T, Hirakata T, Iijima M, Kuwano H. Implication of extracapsular invasion of sentinel lymph nodes in breast cancer: prediction of nonsentinel lymph node metastasis. World J Surg. 2010;34:544–8. 15. van la Parra RF, Peer PG, de Roos WK, Ernst MF, de Wilt JH, Bosscha K. A simple risk score to predict the presence of nonsentinel lymph node metastases in breast cancer patients with a positive sentinel node. World J Surg. 2014;38:1070–6. 16. Gooch J, King TA, Eaton A, et al. The extent of extracapsular extension may influence the need for axillary lymph node
dissection in patients with t1-t2 breast cancer. Ann Surg Oncol. 2014;21:2897–903. Yajima R, Fujii T, Yanagita Y, et al. Prognostic value of extracapsular invasion of axillary lymph nodes combined with peritumoral vascular invasion in patients with breast cancer. Ann Surg Oncol. 2014. Hetelekidis S, Schnitt SJ, Silver B, et al. The significance of extracapsular extension of axillary lymph node metastases in early-stage breast cancer. Int J Radiat Oncol Biol Phys. 2000;46:31–4. Harris L, Fritsche H, Mennel R, et al. American Society of Clinical Oncology 2007 update of recommendations for the use of tumor markers in breast cancer. J Clin Oncol. 2007;25:5287– 312. Colzani E, Liljegren A, Johansson AL, et al. Prognosis of patients with breast cancer: causes of death and effects of time since diagnosis, age, and tumor characteristics. J Clin Oncol. 2011;29:4014–21. Luporsi E, Andre F, Spyratos F, et al. Ki-67: level of evidence and methodological considerations for its role in the clinical management of breast cancer: analytical and critical review. Breast Cancer Res Treat. 2012;132:895–915. van de Vijver MJ, He YD, van’t Veer LJ, et al. A gene-expression signature as a predictor of survival in breast cancer. N Engl J Med. 2002;347:1999–2009. Paik S, Shak S, Tang G, et al. A multigene assay to predict recurrence of tamoxifen-treated, node-negative breast cancer. N Engl J Med. 2004;351:2817–26. Parker JS, Mullins M, Cheang MC, et al. Supervised risk predictor of breast cancer based on intrinsic subtypes. J Clin Oncol. 2009;27:1160–7. Kadoya T, Aogi K, Kiyoto S, Masumoto N, Sugawara Y, Okada M. Role of maximum standardized uptake value in fluorodeoxyglucose positron emission tomography/computed tomography predicts malignancy grade and prognosis of operable breast cancer: a multi-institute study. Breast Cancer Res Treat. 2013;141:269–75. Ohara M, Shigematsu H, Tsutani Y, et al. Role of FDG-PET/CT in evaluating surgical outcomes of operable breast cancer: usefulness for malignant grade of triple-negative breast cancer. Breast. 2013;22:958–63. Sargent DJ, Conley BA, Allegra C, Collette L. Clinical trial designs for predictive marker validation in cancer treatment trials. J Clin Oncol. 2005;23:2020–7. Simon RM, Paik S, Hayes DF. Use of archived specimens in evaluation of prognostic and predictive biomarkers. J Natl Cancer Inst. 2009;101:1446–52. Donegan WL, Stine SB, Samter TG. Implications of extracapsular nodal metastases for treatment and prognosis of breast cancer. Cancer. 1993;72:778–82. Ilknur GB, Hilmi A, Tulay C, et al. The importance of extracapsular extension of axillary lymph node metastases in breast cancer. Tumori. 2004;90:107–11. Stitzenberg KB, Meyer AA, Stern SL, et al. Extracapsular extension of the sentinel lymph node metastasis: a predictor of nonsentinel node tumor burden. Ann Surg. 2003;237:607–12; discussion 612–603. Degnim AC, Reynolds C, Pantvaidya G, et al. Nonsentinel node metastasis in breast cancer patients: assessment of an existing and a new predictive nomogram. Am J Surg. 2005;190:543–50. Mittendorf EA, Hunt KK, Boughey JC, et al. Incorporation of sentinel lymph node metastasis size into a nomogram predicting nonsentinel lymph node involvement in breast cancer patients with a positive sentinel lymph node. Ann Surg. 2012;255:109–15.