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© 1999 American Society for Clinical Oncology Is Axillary Lymph Node Dissection Indicated for Early-Stage Breast Cancer? A Decision AnalysisFrom the Institute of Statistics and Decision Sciences and Center for Clinical Health Policy Research, Duke University; Comprehensive Cancer Center, Department of Surgery, and Department of Radiation Oncology, Duke University Medical Center, Durham, NC; Dana-Farber Cancer Institute, Boston, MA; and National Center for Atmospheric Research, Boulder, CO. Address reprint request to Giovanni Parmigiani, PhD, Institute of Statistics and Decision Sciences, Box 90251, Duke University, Durham, NC 27708; email gp{at}isds.duke.edu
PURPOSE: Axillary lymph node dissection (ALND) has been a standard procedure in the management of breast cancer. In a patient with a clinically negative axilla, ALND is performed primarily for staging purposes, to guide adjuvant treatment. Recently, the routine use of ALND has been questioned because the results of the procedure may not change the choice of adjuvant systemic therapy and/or the survival benefit of a change in adjuvant therapy would be small. We constructed a decision model to quantify the benefits of ALND for patients eligible for breast-conserving therapy. METHODS: Patients were grouped by age, tumor size, and estrogen receptor (ER) status. The model uses the Oxford overviews and three combined Cancer and Leukemia Group B studies. We assumed that patients who did not undergo ALND received axillary radiation therapy and that the two procedures are equally effective. All chemotherapy combinations were assumed to be equally efficacious. RESULTS: The largest benefits from ALND are seen in ER-positive women with small primary tumors who might not be candidates for adjuvant chemotherapy if their lymph nodes test negative. Virtually no benefit results in ER-negative women, almost all of whom would receive adjuvant chemotherapy. When adjusted for quality of life (QOL), ALND may have an overall negative impact. In general, the benefits of ALND increase with the expected severity of adjuvant therapy on QOL. CONCLUSION: Our model quantifies the benefits of ALND and assists decision making by patients and physicians. The results suggest that the routine use of ALND in breast cancer patients should be reassessed and may not be necessary in many patients.
AXILLARY LYMPH NODE dissection (ALND) has long been an integral part of the management of breast carcinoma. Initially, its purpose was to remove the likely first area of tumor spread from the primary lesion in the breast, with the thought that a higher cure rate would result than if only mastectomy were performed. Subsequent clinical trials, however, showed that ALND contributed little to overall survival, despite a relatively high pathologic frequency of axillary nodal involvement in clinically node-negative patients.1 The concept evolved that positive axillary lymph nodes were primarily a marker for a high risk of occult systemic spread, rather than a source of systemic metastases. With the advent of adjuvant systemic therapy, ALND came to be viewed primarily as a staging procedure: it conveyed prognostic information and guided decisions regarding adjuvant systemic therapy. The concept of breast cancer as a systemic disease has led to the increased use of adjuvant therapy in a wide range of patients, with demonstrations of benefits in node-negative as well as node-positive patients.2,3 These results have called into question the rationale for performing ALND. If the information derived from ALND is no longer critical in determining adjuvant therapy for some patients, should it now be omitted in those patients?4-8 ALND is of value if it (1) leads to a more effective adjuvant systemic therapy with improved patient survival; (2) provides local control with a possible increase in survival; or (3) provides prognostic information of value to the patient. These benefits must be considered in light of the long-term complications associated with ALND, as well as the financial cost. In this article, we present a quantitative assessment of the impact on survival (both unadjusted and quality-adjusted) of ALND in patients receiving breast conservation therapy (BCT). Our focus is on BCT patients because ALND is a distinct and separate operation for these patients, as opposed to patients undergoing mastectomy, for whom ALND is more often an integral part of the procedure. Axillary irradiation seems to provide the same local control and survival benefits (if any) of ALND in patients with clinically uninvolved lymph nodes.9 Therefore, ALND is useful if it results in an alteration in a patient's proposed plan of therapy and if that different plan improves survival or decreases morbidity, compared with the best plan in the absence of ALND. For some patients, the information gained from ALND may be valuable separately from the impact that it has on therapeutic decisions. However, we do not incorporate the value of this knowledge in our model. Sentinel node biopsy may be an effective alternative to ALND but is not considered in the model presented here.
Decision Model For this study, we considered patients who had clinically negative axillae and who were undergoing BCT. The decision to perform a node dissection and the selection of appropriate adjuvant therapy are made in light of patient characteristics: namely, age, estrogen receptor (ER) status, and primary tumor size, because the benefits are likely to be different for these groups.10 Because knowing the result of the ALND might lead to a more appropriate choice of adjuvant therapy, we include two decision points: (1) choice of either ALND or radiation therapy (XRT); and (2) choice of adjuvant systemic therapy. The resulting decision tree is shown in Fig 1. 
We considered four alternatives for adjuvant systemic therapy: tamoxifen (T); combination chemotherapy (CT); combination chemotherapy followed by tamoxifen (CT + T); and no adjuvant systemic therapy. All suitable adjuvant combination chemotherapy regimens are assumed to be equivalent in terms of long-term outcome and effects on quality of life (QOL). The alternative of not treating the axilla with either ALND or XRT was not studied in our model. We wanted to use strategies that provide equivalent high probability of local control of axillary disease as well as any survival benefits that may accrue from direct treatment of the axilla. Our goal was to obtain results that do not depend on any additional assumptions about the estimated efficacies of axillary treatments.
Probability Estimates Survival of chemotherapy patients with positive nodes was estimated using a multivariate Cox proportional hazards regression model that included age, ER status, primary tumor size and nodal involvement as prognostic variables, based on the combined Cancer and Leukemia Group B (CALGB) studies 7581, 8082, and 8541.13-15 The maximum follow-up duration in the CALGB studies is 19 years. Rates beyond 19 years were extrapolated on the basis of a constant hazard rate (set to the average hazard rate for years 15 to 19). The hazard rate in the first 19 years is not constant, to account for the greater hazard in the first few months after adjuvant treatment. For this reason, our model is more general than so-called Markov decision models. If ALND is performed, the survival estimates incorporate the results of the dissection. CALGB trials involved only node-positive women. To derive a survival curve for node-negative women, the following strategy was used: (a) For node-negative women with primary tumors larger than 1 cm, results from the Early Breast Cancer Trialists' Collaborative Group overview2 were used to estimate an adjustment ratio between node-positive and node-negative patients receiving chemotherapy. This ratio is 0.42 for the first 4 years and 0.61 for the remainder.2 (b) For node-negative women with primary tumors smaller than 1 cm, the results of Rosen et al16 and Quiet et al17 were used to derive two separate adjustment ratios for women with ER-positive and ER-negative tumors. Mortality rates from causes other than breast cancer were taken from life tables.18 Survival rates for women undergoing adjuvant therapy other than chemotherapy were derived from the previous analysis and from the results of recent Early Breast Cancer Trialists' Collaborative Group overviews.2,3,19 The results among node-positive patients receiving chemotherapy were used as the baseline and then adjusted in accordance with the risk ratios listed in Table 1 to generate survival curves for the other treatment options. Effects that were deemed statistically unstable by the overview investigators2,3 were not modeled. Specifically, we assumed that (1) tamoxifen has no effect of in premenopausal ER-negative patients and (2) adjuvant therapy is equally effective (in terms of risk reduction) in node-negative as well as node-positive women. Recent evidence from the National Surgical Adjuvant Breast and Bowel Project B-1420 trial also shows a risk reduction for node-negative patients that is comparable with that of previously observed node-positive patients.
Additional assumptions of our model are the following: (1) if metastatic disease develops, the duration of time with metastatic disease is not affected by the adjuvant therapy; and (2) local control of subclinical axillary disease can be achieved with XRT in 95% of patients (clinically evident axillary disease requires ALND). Axillary radiation will typically include supraclavicular nodes as well. Therefore, any survival benefit that might be anticipated from administering nodal irradiation to node-positive patients will be realized in patients not undergoing ALND as well.9,12,21
QOL Our primary analysis used a scenario that represents a moderate impact of adjuvant therapies on QOL. This scenario is named Qmoderate and is described in Table 2. For quality adjustments for CT + T (not shown in the table), we used the adjustment factor for CT for the first 6 months and both adjustments thereafter. To investigate the sensitivity of our primary results to QOL adjustments, we compared the results obtained under the Qmoderate scenario to the results obtained under three additional scenarios, termed Qmild, Qsevere, and QALND < XRT (Table 3). Qmild exemplifies a patient who experiences little impact on her QOL from her adjuvant therapy (less than in Qmoderate) and completely recovers from the negative effects of therapy by the end of 1 year. Qsevere reflects a more severe effect of treatment on QOL than Qmoderate. All adjustments for adjuvant therapy vary with time since therapy.
There is a QOL impact of complications from ALND and from XRT. In the Qmoderate, Qmild, and Qsevere scenarios, we assumed the same QOL adjustment for the negative impact of ALND and XRT—namely, half a percent—corresponding to a quality adjustment of 0.995. This quality adjustment is assumed to be constant over time and was applied over and above any adjustments resulting from adjuvant systemic therapy. In scenario QALND < XRT, we assumed that the impact on QOL from adjuvant systemic therapy was the same as that in the Qmoderate scenario and further assumed a negative impact on QOL from ALND that is greater than that from XRT. The quality adjustment for ALND is 0.995, whereas that for XRT is 0.997. The end point of the decision analysis is the gain in expected quality-adjusted life-years (QALYs) resulting from ALND. This effect is evaluated by computing, for all levels of nodal involvement, the survival benefit gained from a change in adjuvant treatment that was dictated by the result of ALND. The expected gain is then the average of these gains, weighted using the probabilities of different levels of nodal involvement for that particular patient type.
We first consider two examples in detail: patients A and B. Patient A is 60 years old, with a primary tumor size between 0.5 and 1 cm. Patient B is 38 years old, with a primary tumor size between 3 and 4 cm. Both have ER-positive tumors and clinically negative axillae. We then examine the sensitivity of the results to QOL adjustments and give summary results for all patient types.
Survival
QOL: Moderate Scenario
For patient A, the best option is T if ALND is not performed (nodal status unknown). If ALND is performed and she is node-negative, she would receive T, whereas if she is node-positive, she would receive CT + T. The gain in QALYs from adding C to T ranges from 0.37 to 0.5 years. Thus ALND can lead to a change in the appropriate adjuvant therapy and increase survival. The magnitude of the resulting benefit is calculated by the difference between the weighted average of the values in the T column and the weighted average of the best option values. For patient A, this magnitude is 0.04 QALYs (approximately 2 weeks). For patient B, CT + T is the treatment leading to the largest expected survival and QALYs, irrespective of nodal status. Therefore, ALND does not lead to a change in adjuvant systemic therapy or result in any survival gain.
QOL: Sensitivity Analysis
In the QALND < XRT scenario, the optimal adjuvant therapy choices are the same as those in the Qmoderate scenario. The difference between ALND and XRT is -0.02 QALYs. The negative value indicates that the decrement in QOL from ALND outweighs the average benefit of CT + T, compared with T alone, in node-positive patients. For all scenarios in patient B, CT + T maximizes survival and QALYs irrespective of nodal status. In the Qmild and Qsevere scenarios, there is no gain from ALND. In the QALND < XRT scenario, there is a loss (-0.04) of average QALYs. As illustrated by the analyses of patients A and B, decisions may vary depending on patient characteristics. Different patients have different probabilities of having positive nodes found. The effectiveness of adjuvant therapies and the importance of the competing causes of death also vary with the patient, the latter increasing with age. Table 8 lists the expected gains in QALYs that result from ALND for all patient types and QOL scenarios. Patients are grouped by age, ER status, tumor size, and the four QOL scenarios. All zero values in Table 8 indicate that adjuvant therapy will be the same regardless of nodal status; hence there can be no gain from ALND. For example, young women with ER-negative tumors will all have chemotherapy prescribed, irrespective of nodal status. All zero values become negative if we assume a decrement in QOL from ALND, compared with XRT (scenario QALND < XRT). Even when gains in QALYs are present, they are small. To further illustrate the results shown in Table 8, Fig 2 shows recommended adjuvant therapy choices for all patient types in the four quality scenarios.
ALND, as a part of the operative management of breast carcinoma, was introduced by Halsted at the start of this century,24 the rationale being to remove the first area of likely tumor spread and, hence, improve the cure. Attempts at less extensive surgery began in the 1930s and 1940s, primarily in Europe. Total mastectomy (TM) and radiation to peripheral lymph nodes was shown to be comparable in outcome to radical mastectomy (RM), leading to the conclusion that XRT could successfully control subclinical disease in lymph nodes.25,26 The first successful efforts at breast conservation were also reported during this time. The National Surgical Adjuvant Breast and Bowel Project further confirmed that TM+ XRT was equivalent to RM. Indeed, TM alone seemed to provide survival equivalent to those of the other two procedures. With the introduction of adjuvant systemic therapy in the 1970s, a renewed emphasis was placed on ALND as a means to select patients with worse prognoses for adjuvant systemic treatment. Major changes have continued in breast cancer management over the last several decades that relate to the issue of whether ALND should be performed:
2.Adjuvant systemic therapy has demonstrated value in many women with negative lymph nodes as well as those who have cancerous nodes. Furthermore, the relative benefits of adjuvant therapy are similar in node-negative and node-positive women.2,3 3The extent of disease in patients newly diagnosed with breast carcinoma has shifted as the use of mammography has grown and the public awareness of breast cancer has increased. Many more patients with mammographically discovered primary tumors that are quite small are now being encountered. These factors have lead a number of authors to re-examine the issue of ALND and to question its routine use.4,5,7,8,12 Arguments that have been marshaled against ALND as standard practice include the following:
2.Very small primary lesions (<0.5 cm), now much more common in the mammography era, have a low probability of nodal involvement,11 and a good prognosis even if a small number of positive nodes are found.28 Thus the survival benefits from ALND are likely to be extremely small in this group. 3.Elderly patients, particularly those with hormone receptor–positive tumors, will often be treated with tamoxifen anyway—irrespective of nodal status—because of the reluctance to use adjuvant chemotherapy in this group. 4.The morbidity of ALND is small but finite, with 10% to 20% of patients exhibiting some decreased range of motion of the shoulder, approximately 80% experiencing numbness in the distribution of the intercostal brachial nerves, 2% to 30% reporting arm edema, and 15% to 50% experiencing breast edema.10,29–31 5.The procedure involves financial costs. Our study uses the methods of decision analysis in an attempt to provide a quantitative framework for these arguments and a realistic guide for practicing oncologists. Our model incorporates quantitative data regarding the frequency of nodal involvement for different primary tumor sizes, the survival benefits to be expected from adjuvant systemic therapy for different patient categories, the effects on survival to be anticipated from causes of death other than breast cancer, and, finally, the QOL adjustments. A decision analysis published earlier32 was confined to T1 patients and did not measure the impact of ALND on specific patient subgroups, as was done here. QOL adjustments are somewhat arbitrary and hard to quantify but are important nevertheless. If there was no QOL trade-off, all patients with invasive breast cancer would receive chemotherapy, and most would also receive tamoxifen. Clearly, physicians and patients presently incorporate QOL considerations in their decision-making. Our model is a step toward quantifying this process. The model could be improved by the incorporation of utilities provided by patients. In the absence of such data, we have assumed four different QOL scenarios, similar to a Q-twist analysis.23 Certain generalizations can be made despite the difficulties with quality adjustments. It is apparent from Table 8 that for many women, there are no benefits from ALND over a broad range of quality scenarios. This is true when no change in adjuvant systemic therapy would result from knowledge of lymph-node status or if ALND is assumed to have a greater negative impact on QOL than XRT. When there is any survival benefit to be derived from ALND, it is small in almost all instances. This overall conclusion critically depends on the fact that the relative benefits of adjuvant therapy are similar in node-negative and node-positive women.2,3 Whether the small gain for some patients is worth performing ALND is a judgment best left to the individual patient and her physician(s). Our sensitivity analysis demonstrates that there are subsets in which the preferred choice is sensitive to the QOL adjustments and others in which it is not. In those subsets in which it is sensitive, the model would suggest that optimization of QALYs can only be achieved by individualizing decisions about node dissection depending on a patient's preferences and the potential impact on her QOL. The subset of women in whom the results are most sensitive to attitudes toward QOL are premenopausal women with small primary tumors. In this group, node-negative women may or may not opt for chemotherapy, depending on their personal values. If they expect a small QOL reduction from chemotherapy, ALND is of little or no value to them since they will elect to receive chemotherapy anyway. If they expect a greater QOL reduction, ALND becomes more desirable, because node-negative women may not wish to receive chemotherapy. A related issue is the use of ALND to categorize patients by nodal status for possible entry into cooperative group trials testing new therapies. Although knowledge of nodal status has been required for almost all large adjuvant trials, it is difficult to justify ALND if no benefit will accrue to the patient from it. Strong consideration should be given to designing future trials that do not mandate ALND as an eligibility requirement. Sentinel node biopsy has been proposed as an alternative to ALND.33,34 The accuracy of this procedure in predicting nodal status and any potential decrement in QOL remain to be fully determined, but sentinel node biopsy may have less long-term morbidity than ALND. The expected survival gains resulting from the information gathered by sentinel node removal are unlikely to be greater than those derived from traditional ALND. However, if sentinel node biopsy proves to offer accurate prognostic information with minimal morbidity, it may produce better quality-adjusted survival for many patients than would either of the two options considered here. Our model provides a basis for exploring these issues in more detail in future analyses. An additional issue is the possibility that adjuvant high-dose chemotherapy (with stem-cell support) may be of benefit to women with large numbers of positive lymph nodes (for example, women with 10 or more positive lymph nodes). Should future phase III trials demonstrate this benefit, such information could easily be incorporated into the model. In conclusion, our model suggests that ALND should not be performed as a routine part of therapy for patients with breast carcinoma who are undergoing BCT and XRT. Instead, physicians should consider precisely how therapy would be changed and what benefits would be derived from the procedure. We hope that this model will help physicians clarify their own thinking about the appropriateness of ALND and facilitate the counseling of individual women facing this decision. Future studies may explore the use of the model as a counseling tool in a trial aimed at helping physicians and patients make decisions regarding ALND. We recognize that women may choose to have a node dissection to obtain prognostic information; the value of ALND to them may go beyond that of improving decisions about adjuvant systemic therapy. Our model can provide a framework for investigating whether patients value the prognostic information per se provided by ALND, even when the results will not lead to a change in subsequent clinical management.
We are indebted to the Cancer and Leukemia Group B for allowing us to use prognostic data from their studies for node-positive breast cancer.
The research in this study was performed when all authors were affiliated with Duke University and supported by grant no. NCI P50 CA68438 from the National Institutes of Health under the Specialized Program of Research Excellence in Breast Cancer and planning grant no. NCI R21-CA68438-01.
1. Fisher B, Redmond C, Fisher ER: Ten-year results of a randomized clinical trial comparing radical mastectomy and total mastectomy with or without radiation. N Engl J Med 312:674-681, 1985[Abstract] 2. Early Breast Cancer Trialists Collaborative Group: Systemic treatment of early breast cancer by hormonal, cytotoxic, or immune therapy. Lancet 339:1-15, 71-85, 1992 3. Early Breast Cancer Trialists Collaborative Group: Tamoxifen for early breast cancer: An overview of the randomised trials. Lancet 351:1451-1467, 1998[Medline] 4. Cady B: Is axillary lymph node dissection necessary in the routine management of breast cancer? No. Important Adv Oncol 251-256, 1996 5. Moore MP, Kinne DW: Is axillary lymph node dissection necessary in the routine management of breast cancer? Yes. Important Adv Oncol 245-250, 1996
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Haffty B, Ward B, Pathare P, et al: Reappraisal of the role of axillary lymph node dissection in the conservative treatment of breast cancer. J Clin Oncol 15:691-700, 1997 7. Silverstein MJ, Gierson ED, Waisman JR, et al: Axillary lymph node dissection for T1a breast carcinoma: Is it indicated? Cancer 73:664-667, 1994 8. Epstein RJ: Routine or delayed axillary dissection for primary breast cancer? Eur J Cancer 31A:1570-1573, 1995
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Early Breast Cancer Trialists Collaborative Group: Effects of radiotherapy and surgery in early breast cancer. N Engl J Med 333:1444-1455, 1995
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Lin PP, Allison DC, Wainstock J, et al: Impact of axillary lymph node dissection on the therapy of breast cancer patients. J Clin Oncol 11:1536-1544, 1993 11. Carter CL, Allen C, Henson DE: Relation of tumor size, lymph node status and survival in 24,740 cases of breast cancer. Cancer 63:181-187, 1989[Medline] 12. Recht A, Houlihan MJ: Axillary lymph nodes and breast cancer: A review. Cancer 76:1491-1512, 1995[Medline] 13. Wood W, Weiss R, Tormey D, et al: A randomized trial of CMF versus CMFVP as adjuvant chemotherapy in women with node-positive stage II breast cancer: A CALGB study. World J Surg 9:714-718, 1985[Medline]
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Perloff M, Norton L, Korzun A, et al: Postsurgical adjuvant chemotherapy of stage II breast carcinoma with or without crossover to a non-cross-resistant regimen: A cancer and Leukemia Group B study. J Clin Oncol 14:1589-98, 1996
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Wood W, Budman D, Korzun A, et al: Dose and dose intensity of adjuvant chemotherapy for stage II, node-positive breast carcinoma. N Engl J Med 330:1253-1259, 1994 16. Rosen P, Groshen S, Saigo P, et al: A long-term follow-up study of survival in stage I (T1N0M0) and stage II (T1N1M0) breast carcinoma. J Clin Oncol 7:355-366, 1989[Abstract] 17. Quiet CA, Ferguson DJ, Weichelsbaum RR, et al: Natural history of node-negative breast cancer. J Clin Oncol 15:1144-1151, 1995 18. Thernau TM: A Package for Survival Analysis in S. Rochester, Minnesota, Mayo Foundation, 1996 19. Early Breast Cancer Trialists Collaborative Group: Polychemotherapy for early breast cancer: An overview of the randomised trials. Lancet 352:930-942, 1998[Medline]
20.
Fisher B, Dignam J, Bryant J, et al: Five versus more than five years of tamoxifen therapy for breast cancer patients with negative lymph nodes and estrogen receptor-positive tumors. J Natl Cancer Inst 88:1529-1542, 1996 21. Haffty BG, Fischer D, Fischer JJ: Regional nodal irradiation in the conservative treatment of breast cancer. Int J Radiat Oncol Biol Phys 19:859-865, 1990[Medline] 22. Pliskin JS, Shepard D, Weinstein MC: Utility functions for life years and health status: Theory, assessment, and application. Oper Res 28:206-224, 1980 23. Gelber RD, Goldhirsch A, Cavalli F: Quality-of-life-adjusted evaluation of adjuvant therapies for operable breast cancer. Ann Intern Med 114:621-628, 1991 24. Halsted WS: The result of operations for the cure of the breast performed at the Johns Hopkins hospital from June 1889 to January 1894. Johns Hopkins Hosp Bull 4:279, 1894-1895 25. Keynes G: Conservative treatment of cancer of the breast. Br Med J 2:643-647, 1936 26. Johansen H, Kaae S, Scheiodt T: Simple mastectomy with postoperative irradiation vs. extended radical mastectomy in breast cancer. Acta Oncol 29:709-715, 1990[Medline] 27. Morris A, Morris R, Wilson J, et al: Breast conserving therapy vs. mastectomy in early stage breast cancer: A meta-analysis of ten years survival. Cancer J 3:6-12, 1997 28. Quiet C, Ferguson D, Weichelsbaum RR, et al: Natural history of node-negative breast cancer: The curability of small cancers with a limited number of positive nodes. J Clin Oncol 14:3105-3111, 1996[Abstract] 29. Ivens D, Hoe A, Podd T, et al: Assessment of morbidity from complete axillary dissection. Br J Cancer 66:136-138, 1992[Medline] 30. Goss P, Hack T, Cohen I, et al: Long-term physical and psychological morbidity of axillary node dissection in patients with breast cancer. Proc Am Soc Clin Oncol 15:123, 1996 (abstr) 31. Chu L, Bowen G, Peterson B, et al: Long-term complications following axillary node dissection (alnd). Proc Am Soc Clin Oncol 15:153, 1996 (abstr) 32. Velanovich V: Axillary lymph node dissection for breast cancer: A decision analysis of T1 lesions. Ann Surg Oncol 5:131-139, 1998[Abstract] 33. Giuliano A, Kirgan D, Guenther J, et al: Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg 220:391-398, 1994[Medline] 34. Albertini JJ, Lyman GH, Cox C, et al: Lymphatic mapping and sentinel node biopsy in the patient with breast cancer. JAMA 276:1818-1822, 1996[Abstract] Submitted September 23, 1998; accepted January 6, 1999. This article has been cited by other articles:
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Copyright © 1999 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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ABSTRACT
INTRODUCTION
, decision between ALND and XRT. 
NS, information point representing nodal status, with branches indicating outcomes of the dissection. 
