Dr. Stringer has done an excellent job of reviewing the anatomic, biologic, diagnostic, and therapeutic considerations that impact on the management of nodal metastases from head and neck malignancies. This is a thorough summary of the current literature. However, the fact that the literature in this area contains few prospective controlled studies makes it difficult to reach firm conclusions , and thus a spectrum of approaches can be justified. Because of this vulnerability in the literature, our knowledge base is weakened, and accordingly, it is important to resist a dogmatic approach. Therefore, we have to be careful about using such words as "must" or "indicated" when describing clinical approaches. I have concerns that there is insufficient evidence to justify the use of that type of strong language, which was occasionally seen in this review.
The description of the anatomy represents an excellent summary. There is no question that neck nodal dissections represent an "anatomic" surgical approach. It is important for the reader to understand, however, that there is no strict compartmentalization of the lymphatic system that segregates it from the structures that are preserved in different forms of nodal dissections.
Dr. Stringer cites the spinal accessory nerve as an example of this lack of anatomic compartmentalization in the neck. I am somewhat confused by his anatomic description of the course of the spinal accessory nerve. He describes the superior end of this nerve as being located in both the upper portion of level II and level V. The superior course of the spinal accessory nerve places it in proximity to the internal jugular vein and the upper jugular nodes. It is not located in the upper portion of the posterior triangle. This is a clinically important anatomic fact. Many of the earlier reports in the literature justifying the preservation of the spinal accessory nerve cited the relative infrequency of nodal involvement of this structure based on the infrequency of metastatic nodes in the lower posterior triangle. However, this nerve is at greatest risk of involvement with nodal metastatic disease in its superior course .
Small Positive Nodes
The author refers to the fact that the size of a metastatic node is directly associated with an increased risk of extracapsular spread. I do not challenge that statement, but it is important for the reader to recognize the disturbingly high frequency of extranodal spread associated with even small positive nodes. It is this possibility of extracapsular spread in small lymph nodes that poses a potential threat to those surgical approaches that save structures that are not normally involved with the lymphatic system.
Dr. Stringer mentions that there are no nodes in the fascial wrappings of the sternocleidomastoid muscle or carotid artery, and that "all lymph nodes may be removed with a modified neck dissection." That is certainly an anatomic possibility. Unfortunately, however, the clinician currently has no mechanism for determining whether some of those small lymph nodes that are adjacent to either the sternocleidomastoid muscle or carotid artery may have extracapsular spread, with microscopic contamination of structures that are retained in that type of neck dissection. This worrisome possibility and our current inability to diagnose it remain concerns when one performs neck dissections that preserve these structures. When such neck dissections are undertaken and the pathology report demonstrates the presence of extranodal disease, the clinician may want to consider postoperative radiation therapy as a means of eradicating any residual microscopic disease.
The author also discusses the increased risk of distant metastases, and corresponding decrease in survival, with the position of metastatic nodes in the neck and an increased number of positive nodes. The literature is somewhat confusing on this point. An analysis from the University of Iowa could not confirm the correlation between numbers of positive nodes and increased distant metastases or compromised survival .
A Surgical Challenge
The relationship of the carotid artery to neck nodal disease continues to be a surgical challenge. This article summarizes the data documenting that carotid artery resection and replacement have an acceptable morbidity and mortality. There is some information to suggest that this procedure does not improve survival. However, we continue to routinely work with our vascular surgeons to replace the carotid artery in those patients who have metastatic nodal fixation to the artery. Our experience with carotid resection and replacement, with or without concurrent entrance into the oral cavity or pharynx, is favorable enough for us to advocate its continued use. There are no controlled studies that allow us to unequivocally demonstrate improved survival. However, intuitively, it would seem that disease-free interval and quality of life, if not survival, would have to be improved when the disease is removed, as opposed to when it is not.
Incidence of Atrophy
Dr. Stringer comments on the fact that modified neck dissections sparing only the spinal accessory nerve result in atrophy of the trapezius muscle in upwards of 50% of patients. Preservation of the spinal accessory nerve represents the single most important step for minimizing the morbidity of neck dissection. It is my impression that the frequency of trapezius atrophy with preservation of only the spinal accessory nerve is not as high as 50%. However, the author's statement has stimulated me to review the Ohio State experience to objectively analyze this approach.
In summary, this article is a useful review for the clinician. Readers should keep in mind, however, that our knowledge base in this area is somewhat weak, in that it is based primarily on uncontrolled analyses of patients. Because of that inability to make unequivocal conclusions, it is critically important to individualize the therapeutic approach, which will be affected by what is known in addition to the realities of where and how a particular patient is treated.
For example, there is no question that the results of performing modifications of surgical neck dissections can be affected by the experience and expertise of the surgeon. There is also no question that the proficiency of the radiation oncologist will have an impact on the ultimate treatment outcome. Therefore, it is the individual physician who knows his/her technical skills and the treatment capabilities of the local medical center who is in the best position to recommend the optimal approach for a particular patient.
1. Schuller DE, et al: Spinal accessory lymph nodes: A prospective study of metastatic involvement. Laryngoscope 88:439, March 1978.
2. Schuller DE, et al: The prognostic significance of metastatic lymph nodes. Laryngoscope 40:557-570, April 1980.