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Annals of Surgical Oncology 8:7-12 (2001)
© 2001 Society of Surgical Oncology

ORIGINAL ARTICLES

Localizing the Sentinel Node Outside of the Specialty Center: Success of a Lymphatic Mapping Course in Disseminating New Technology

Emmanuel E. Zervos, MD, Sanjoy Saha, MD, Stacy Hoshaw-Woodard, PhD, Grayson H. Wheatley, MD and William E. Burak, Jr., MD

From the Division of Surgical Oncology (EEZ, SS, GHW, WEB) and the Biostatics Program (SHW), Arthur G. James Cancer Center and Richard J. Solove Research Institute, The Ohio State University, Columbus, Ohio.

Correspondence: Address correspondence and reprint requests to: Dr. Emmanuel E. Zervos, Division of Surgical Oncology, N924 Doan Hall, 410 W. 10th Ave., Columbus, OH 43212; Fax: 614-293-3256; E-mail: zervos.2 @osu.edu


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
BACKGROUND: Sentinel node biopsy (SNB) is an evolving technology in the management of breast cancer. The purpose of this study was to determine the success of an SNB course in emphasizing principles for participants to successfully initiate an SNB program at their institution.

METHODS: Participants in a university-sponsored course were queried 6 to 18 months after the course regarding their success in initiating SNB in their practice. Univariate analysis was used to determine the likelihood of implementing a SNB program.

RESULTS: Ninety-one participants responded. Of these respondents, 56 had initiated an SNB program at their hospital, and 20 had completed a "validation" phase. "Validation" consisted of less than 10 cases for 11 respondents, 11 to 20 cases for 5 respondents, and 20 to 30 cases for 3 respondents and >30 cases for 1 respondent. Twenty-eight percent initiated the learning curve without an Institutional Review Board (IRB) protocol, and a further 20% went on to utilize SNB without axillary dissection in sentinel node-negative patients without IRB approval. Univariate analysis revealed that surgeons practicing in a group whose caseload consisted of more than 25% breast surgery cases were most likely (P < 0.05) to implement SNB in their practice.

CONCLUSIONS: Success in applying SNB after a course is high among surgeons in groups with a significant breast caseload, although recommendations for obtaining institutional approval and completing a 30-case validation series are often disregarded.

Key Words: Sentinel node— • Breast cancer.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 
Lymphatic mapping, initially developed to aid in the treatment of melanoma, has gained unprecedented momentum in the treatment of breast cancer since the first published breast cancer success in 1993.1 In fact, the number of MEDLINE citations for sentinel node in breast cancer has now surpassed those for use of the technique in melanoma. Although lymphatic mapping and sentinel node biopsy (SNB) is not yet the standard of care in breast cancer, it has been embraced by surgical oncologists and breast surgeons because of its low morbidity and high degree of accuracy in predicting the pathologic characteristics of the remaining nodes in the axilla.2–5

The evolution of the current SNB technique has paralleled a similar evolution in medical and patient education. Physicians are reaching out to large audiences through telemedicine and the Internet, and many patients are learning more about their disease and its treatment "on line" than in physicians’ offices. Today’s breast cancer patient arrives at the initial surgical consultation aware of sentinel node technology and often requests it as part of her treatment. All of these factors have created a demand for training opportunities to extend sentinel node technology outside of the specialty center and into the hands of those surgeons who care for the majority of new breast cancer cases diagnosed each year. Most specialty centers now sponsor some type of training course, and as the procedure becomes more popular, their number and breadth is expected to increase. Courses typically cover all aspects of lymphatic mapping for breast and melanoma, including the pathologic, oncologic, and nuclear medicine implications of the procedure.

Performance of SNB for breast cancer is not difficult. Its early proponents recognized, however, that its subtleties could not be mastered in a single course. They further recognized that the implications of improper use of such technology are potentially catastrophic, in that a window of treatment opportunity may close prematurely in a patient whose sentinel node is incorrectly identified or incorrectly labeled negative. As a result, each of the centers that refined the technique has attempted to define the learning curve to help determine the requisite number of validation cases surgeons must perform before applying the technology exclusively to stage the axilla.6,7 These studies ultimately led to published guidelines from the American Society of Breast Surgeons in November of 1998. The guidelines recommend that surgeons anticipating use of SNB as their sole means of staging the axilla first should perform 30 validation cases. The guidelines further recommend that, in the validation phase, the surgeon should self report accurate identification of the sentinel node 85% of the time with a false-negative rate less than or equal to 5%.8 The guidelines are emphasized in the lymphatic mapping course, and the courses are designed to provide information necessary to maximize each participant’s ability to meet them.

Lymphatic mapping courses are not designed to, and cannot, validate participants. Rather, these courses introduce participants to the technique of SNB and address issues such as equipment, IRB, radiation safety, and microstaging that are essential in performing the procedure safely and accurately. To date, thousands of surgeons have participated in lymphatic mapping courses across the United States, and there is at least one published report documenting that sentinel node technology can be successfully applied outside of the specialty center.9 No course sponsor, however, has evaluated the impact that their course has had on disseminating properly applied sentinel node technology to the community. Our institution has sponsored eight such courses to date involving more than 200 participants drawn from Ohio, West Virginia, and Indiana. The purpose of this study was to critically evaluate our success in training surgeons to perform the technique properly using the principles emphasized in the course and to determine our "yield" in terms of course participants who ultimately proceed to apply the technology in their practice.


   METHODS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
The Course
Seven lymphatic mapping courses were sponsored by the Arthur G. James Cancer Center and Richard J. Solove Research Institute between March 1998 and March 1999. The course takes 8 hours and is divided into two sessions: a multidisciplinary didactic session and a "hands on" animate laboratory. The didactic portion of the course emphasizes theory, application, and technique of all aspects of SNB for breast cancer and melanoma using radiolabeled colloid and blue dye. Radiation safety issues, including isotope dosimetry and handling, are strongly emphasized. Participants are given a course syllabus, which includes current guidelines regarding application of SNB, seminal articles that support the concepts, and sample IRB protocols which the participants are encouraged to adapt to meet their own institution’s guidelines. Participants are strongly encouraged to perform an IRB-sponsored validation study consisting of 25 to 30 cases before offering SNB without axillary dissection. Representatives from probe manufacturers are available to answer questions regarding characteristics, use, and acquisition of the various probes. The animate portion of the course allows hands-on use of both the isotope and blue dye using either a porcine or a feline model. Course instructors are available for the duration of the session to answer questions and assist with the technique as needed.

The Survey
A survey consisting of 21 questions was mailed to each course participant in August of 1999. The survey included questions regarding practice demographics and reasons for participating in the course (or pursuing training in SNB). Participants were asked whether they had initiated a learning curve and, if so, what limitations or obstacles were encountered in establishing SNB at their respective institutions. Participants were further questioned regarding IRB approval and details of how they executed SNB. Finally, participants were asked whether they thought the course was useful in helping them to establish a program at their hospital.

Statistics and Data Analysis
Responses were entered into a statistical database (STATA, College Station, TX), and univariate tests were conducted to assess the relation between each of the survey questions and usage of the sentinel node program. Nonparametric rank-sum tests were used to test the equality of the distributions. Multivariate logistic regression was then conducted to determine the factors that would best predict the success of applying the sentinel node program. Backward selection was used to obtain the best model of prediction by dropping the nonsignificant variables, one at a time. Significance was accepted at a P value less than .05. Respondents were then divided into three groups based on whether or not they used the technology and, if so, whether they offered it as the sole means of staging the axilla. Demographics and limiting factors were then reanalyzed based on these three groups, and trends regarding demographics, limiting factors and technical aspects of the procedure were noted.


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
DISCUSSION
 REFERENCES
 
Group Demographics
Ninety-one of the 200 surveys mailed were returned. Group characteristics of the respondents are listed in Table 1. Most course participants were male, and this was reflected in the distribution of male respondents to the survey. Only one respondent was in university practice; the vast majority were in community-based group practices located in larger cities. Most respondents had been in practice more than 5 years, with breast surgery comprising one quarter or less of each practice for more than 70% of the respondents.


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  		Table 1. Characteristics of respondents to sentinel node survey
 
Univariate Analysis/Logistic Regression to Determine Likelihood to Apply Sentinel Node Biopsy
Demographic data listed in Table 1 plus questions regarding patient interest were subjected to univariate analysis with logistic regression applied to significant factors to determine respondents’ likelihood of using SNB based on their response to these questions. Results of this analysis are listed in Table 2. Surgeons in group practices whose practices consisted of more than 25% breast surgery were more likely to use the technology than their solo counterparts with limited breast practices. These two factors were also significant predictors when subjected to logistic regression analysis (P = .02 and .03, respectively). In addition, respondents who reported a high level of interest within their practice population were also statistically more likely to apply the technology.


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  		Table 2. Univariate {chi}2 Results
 
Breakdown of Respondents Based on Success of Applying Sentinel Node Biopsy in Practice
Thirty-five respondents (38%) had not initiated an SNB program in their hospital within 1 year of taking the course. Fifty-six respondents (62%) initiated or completed a validation series, with 20 of these respondents going on to apply the technology as their sole means of staging the axilla. Demographics in these groups are broken down in Table 3 and then further broken down controlling for each variable as to whether or not SNB was applied (e.g., Of the female respondents, what percentage did not initiate a validation phase? What percentage initiated validation? and what percentage completed validation?). Female surgeons were more likely than male surgeons to apply the technology (77% vs. 55%, P < .05), despite their lower representation in the group as a whole (14%). Group practitioners also were more likely to initiate or complete validation compared to their solo counterparts (68% vs. 29%). As the percentage of breast surgery in each practice increased, so too did the likelihood that SNB would be initiated or applied in those practices. Most (64%) of the respondents had been in practice between 5 and 20 years, and they were more likely to initiate a program than surgeons early or late in their careers. Except for one respondent who was in a university-based practice, neither hospital nor academic affiliation was correlated with likelihood to apply SNB.


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  		Table 3. Characteristics of respondents not using technology, initiating learning curve, and utilizing technology (n = 91)
 
Procedure-Related Variables
Table 4 examines procedure-related variables evaluated in the two groups of respondents that went on to initiate or complete a validation phase. No respondents reported using only the probe to localize the sentinel node, although a small fraction did report using blue dye only. (Most of the latter group of respondents had not yet purchased a gamma probe). Roughly half of the respondents reported using lymphoscintigraphy, despite a strong bias against its routine application in our institution and at our course,10 and most respondents had their radiology colleagues inject the isotope (Table 4).


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  		Table 4. Procedure-related variables in respondents initiating validation or offering technology as sole means of staging axilla (n = 56)
 
Most respondents who used the procedure did so under the auspices of the IRB at their institutions, although some did not and even went on to apply SNB as definitive staging without approval. Only one respondent who completed the validation phase performed the 30 validation cases recommended by the ASBS; 80% of those going on to offer SNB exclusively documented less than 20 validation cases (Table 4).

Limitations and Obstacles Encountered While Initiating a Sentinel Node Biopsy Program
Figure 1 delineates those obstacles or limitations most commonly encountered for the group of respondents as a whole and are then analyzed based on likelihood to adopt the technology. Ownership of the probe was, by far, the most frequently cited deterrent to initiating a program, followed by difficulty in obtaining or submitting IRB approval. Bias against the procedure by referring physicians, difficulty obtaining nuclear medicine approval or support, and patient refusal also were cited as deterrents, but far less frequently.



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  		FIG. 1. Limiting factors in applying SNB. irb, institutional review board; nuc-med, nuclear medicine; SNB, sentinel node biopsy.

 
General Responses
Twenty percent of the respondents believed that SNB should be considered the standard of care in node-negative breast cancer patients, whereas 80% believed that the technology was good but that validation in larger studies was necessary. Almost half of the respondents felt compelled to learn the procedure because of market forces in their practice, and all respondents considered the course a valuable adjunct in the establishment of an SNB program at their institution.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
REFERENCES
 
Few surgeons would fail to acknowledge the impact that sentinel node biopsy has had on the management of breast cancer over the past 5 years. Now, with patients becoming more knowledgeable about their disease through resources such as the Internet and patient support groups, sentinel node biopsy no longer is a procedure that can be practiced only at universities and specialty centers. The need to educate community and non-university surgeons in the concept of sentinel node technology has arisen from both patients and referring physicians, and several courses have been established across the country to meet this need. The purpose of this study was to analyze the success of one such course at a large Midwestern university in disseminating the technology to the surrounding community.

The respondents to our survey represent a cross section of surgeons who care for the majority of breast disease in this country. They are, for the most part, group practitioners in community-based practice. They are mostly male, but female surgeons do participate and, are more likely to apply the SNB in their practices. Because the likelihood of applying SNB was directly correlated with the distribution of breast cases in each respondent’s practice, the higher likelihood of women applying the technology may be a reflection of the higher percentage of breast cases in these surgeons’ practices or a greater sensitivity for the morbidity of routine axillary dissection.11,12 As one might predict, practices that reported a high level of patient interest also were more likely to adopt SNB in their management of breast cancer.

We were pleased to note that the majority of respondents to our survey did go on to initiate a sentinel node program in their practice. Allowing for some participants who are either "auditing" the course (i.e., non-surgeons) or were in the process of accumulating the necessary tools and approval, we were pleased with the penetration of our course into the surrounding community. It is interesting to note that equipment and IRB considerations are the most commonly cited obstacles and that issues surrounding the nuclear medicine approval and support of the procedure were not as problematic.

It is both surprising and of concern that recommendations regarding the necessity for IRB approval and completion of a validation phase are not always followed. It is clear that most sentinel node failures (non-localizations and false-negative results) will occur in the first 25 cases.6,7 Almost all (95%) of the surgeons offering SNB as an alternative to axillary dissection in this survey did not complete 30 validation cases, and 55% of those completed less than ten. In the absence of a credentialing body or quality assurance mandate, this is an especially alarming trend. The multicenter trial published by Krag et al.13 clearly documents the correlation between an individual surgeon’s experience with the procedure and his or her ability to localize the sentinel node. These findings were so convincing that each of the current prospective trials evaluating SNB (ACSOG-Z0010 and NSABP B-32) has incorporated safeguards to ensure that surgeons have adequate experience and/or supervision before participating in the study. The appropriate application of sentinel node technology will not become the standard of care if an inordinate number of axillary recurrences arise from improper application of the technology outside of the specialty centers where validation and quality assurance is a continuous process. Furthermore, without IRB approval, there is no guarantee to the patient or the hospital that guidelines are being followed correctly and that patients are being counseled appropriately on the experimental nature of the procedure in the validation phase. We believe that these issues must be emphasized even more strongly in future courses, and we have begun to do so in our own courses subsequent to this study.

Although not yet the standard of care for breast cancer, sentinel node biopsy clearly is the most efficient means of staging breast cancer patients when applied and executed properly. Unfortunately, this technology is being offered by some surgeons who may not have the experience necessary to perform this procedure with a high degree of accuracy.


   Footnotes
 
Presented at the 53rd Annual Meeting of the Society of Surgical Oncology, New Orleans, Louisiana, March 16-19, 2000.

Received for publication March 17, 2000. Accepted for publication August 8, 2000.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 REFERENCES
 

  1. Krag DN, Weaver DL, Alex JC, et al. Surgical resection and radiolocalization of the sentinel lymph node in breast cancer using a Gamma probe. Surg Oncol 1993; 2: 335–9.[CrossRef][Medline]
  2. Krag D, Weaver D, Ashikaja T, et al. The sentinel node in breast cancer; a multicenter validation study. N Engl J Med 1998; 339: 941–6.[Abstract/Free Full Text]
  3. Giuliano AE, Kirgan DM, Guenther JM, et al. Lymphatic mapping and sentinel lymphadenectomy for breast cancer. Ann Surg 1994; 220: 391–401.[Medline]
  4. Albertini JJ, Lyman GH, Cox C, et al. Lymphatic mapping and sentinel node biopsy in the patient with breast cancer. JAMA 1996; 276: 1818–22.[Abstract]
  5. O’Hea BJ, Hill A, El-Shirbiny AM, et al. Sentinel lymph node biopsy in breast cancer: initial experience at Memorial Sloan-Kettering Cancer Center. J Am Coll Surg 1998; 186: 423–7.[CrossRef][Medline]
  6. Cox CE, Pendas S, Cox JM, et al. Guidelines for sentinel node biopsy and lymphatic mapping of patients with breast cancer. Ann Surg 1998; 227: 645–53.[CrossRef][Medline]
  7. Cody HS, Hill A, Tran KN, et al. Credentialing for breast lymphatic mapping: how many cases are enough? Ann Surg 1999; 229: 723–8.[CrossRef][Medline]
  8. Edwards M, Giuliano A, Reintgen D, Tafra L. American Society of Breast Surgeons Concensus Statement on the Guidelines for Performance of Sentinel Lymph Node Biopsy for Breast Cancer. ASBS Press Release, November 2, 1998, Laurel, MD.
  9. Guenther JM, Krishnamoorthy M, Tan LR. Sentinel lymphadenectomy for breast cancer in a community managed care setting. Cancer J Sci Am 1997; 3: 336–40.[Medline]
  10. Burak WE, Walker MJ, Yee LD, et al. Routine preoperative lymphoscintigraphy is not necessary prior to sentinel node biopsy for breast cancer. Am J Surg 1999; 177: 445–9.[CrossRef][Medline]
  11. Roses DF, Brooks AD, Harris MN, et al. Complications of level I and II axillary dissection in the treatment of carcinoma of the breast. Ann Surg 1999; 230: 194–201.[CrossRef][Medline]
  12. Hack TF, Cohen L, Katz J. Physical and psychological morbidity after axillary lymph node dissection for breast cancer. J Clin Onc 1999; 17: 143–9.
  13. Krag DN, Weaver D, Ashikaga T, et al. The sentinel node in breast cancer-a multicenter validation study. N Engl J Med 1998; 339: 941–6.



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