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Neck Metastases

Cernea CR, Dias FL, Fliss D, Lima RA, Myers EN, Wei WI (eds): Pearls and Pitfalls in Head and Neck Surgery. Basel, Karger, 2012, pp 36–37

DOI: 10.1159/000338005

2.1 Preoperative Workup of the Neck in Head and Neck Squamous Cell Carcinoma

Michiel van den Brekel Frans J.M. Hilgers

Netherlands Cancer Institute - Antoni van Leeuwenhoek Hospital, Institute of Phonetic Sciences, University of Amsterdam, Amsterdam, The Netherlands

P E A R L S

• Imaging is crucial in evaluating the extent of metastatic disease and can play a pivotal role in treatment planning.

• MRI is quite specific in determining extranodal spread, which is a parameter used to indicate chemoradiation.

• Imaging, especially PET-CT and ultrasound-guided fine needle aspiration cytology (US-FNAC), can detect occult metastases if larger than 5-6 mm.

• The only (invasive) technique to further improve detection of occult metastases is sentinel node biopsy (SNB).

P I T F A L L S

• The majority of occult metastases cannot be detected using the current imaging techniques.

• Not treating the neck electively with either surgery or radiotherapy is only warranted in tumors with a low risk of occult metastases and when adequate imaging follow-up is ensured.

• As the pathology of neck dissection specimens is not very accurate either, a negative pathology report does not guarantee that no metastases are present.

• Prediction of the metastatic potential of a tumor using gene expression profiling has not proven to be very accurate thus far.

Introduction

Pretreatment workup of the neck is important for deciding on whether or not to treat the (contralateral) neck and how extensive treatment should be. Pretreatment imaging helps to assess the extent of neck disease or the infiltration into crucial structures to determine operability. Tumor encasement of the carotid artery of more than 270° is rarely operable. Assessment of necrosis, tumor volume, extranodal spread, involvement of levels IV and V, retropharyngeal lymph nodes or paratracheal lymph nodes are important. In a N+ neck, selective neck dissection (SND) is still controversial, although recent evidence supports its effectiveness in limited disease [1]. Also, with the advent of intensity-modulated radiotherapy, the fields and doses of radiotherapy are influenced by the status of the neck. When macroscopic extranodal spread exists, usually detected by MRI with high specificity, chemoradiation is indicated, obviating the need for surgery in many primary tumor sites.

In a N0 neck, one can opt for a wait-and-see policy, SNB, SND, or elective neck irradiation [2]. Unfortunately, palpation is not very sensitive and the risk of occult metastases is in the range of 20-50% for most squamous cell carcinomas of the upper aerodigestive tract. This risk is dependent on the site of the primary, the size, and many tumor-specific features like the gene expression profile [3, 4].

To increase the accuracy of neck staging, imaging has been popularized since the 1980s. CT or MRI are unreliable for the detection of metastases smaller than 7-8 mm. The advent of new MRI techniques is promising, but this problem is still unsolved [5]. PET and PET-CT have increased the sensitivity and specificity, but metastases smaller than 5 mm are seldom detected [6]. US-FNAC is an ideal technique both for initial assessment and follow-up, and it has been widely used for the assessment of the N0 neck [7]. The major advantage is the ability to detect cytologically proven disease in very small lymph nodes, with specificity around 100%. However, the reported sensitivity of US-FNAC in the N0 neck varies widely [8]. We recently showed that there is a large interobserver variation in the accuracy of US-FNAC [9]. Also, the histopathological examination overlooks a significant percentage of occult micrometastases. Thus, the sensitivity of any imaging technique is overestimated when the histopathology is used as gold standard instead of follow-up of the neck.

SNB has been shown to be very reliable in detecting occult metastases. It is a very accurate technique, especially when combined with SPECT-CT or fluorescence to distinguish between the primary tumor and the first echelon lymph nodes. However, it is a surgical procedure that often leads to a completion neck dissection.

Practical Tips

As no currently available imaging technique can detect small metastases reliably, in treatment planning one should consider the risk of occult metastases and either treat the neck electively or use a very stringent follow-up protocol including imaging at regular intervals.

As a wait-and-see policy for the N0 neck leads to delayed detection of neck metastases in 15-40% of the patients (depending on the accuracy of imaging and patient population), prognosis is usually worse due to more extensive disease.

Ultrasound is only trustworthy when performed by a skilled ultrasonographer, either the surgeon or the radiologist.

Although the levels I—III are at most risk in most head and neck carcinomas, special attention should be given to retropharyngeal and paratracheal nodes. Any node larger than 5-6 mm in these areas is suspicious.

Conclusion

Although in the last decades imaging has tremendously increased our ability to stage tumors and optimize treatment planning, we are still unable to detect small metastases that frequently occur in head and neck cancers. The controversy of elective SND and the prognostic impact of a wait-and-see policy still persist. Imaging does have a place in the assessment of tumor extent and operability as well as determining optimal treatment.

References

1 Pagedar NA, Gilbert RW: Selective neck dissection: a review of the evidence. Oral Oncol 2009;45:416–420.

2 van den Brekel MW, Castelijns JA: What the clinician wants to know: surgical perspective and ultrasound for lymph node imaging of the neck. Cancer Imaging 2005;5(suppl): S41–S49.

3 Sparano A, Weinstein G, Chalian A, Yodul M, Weber R: Multivariate predictors of occult neck metastasis in early oral tongue cancer. Otolaryngol Head Neck Surg 2004;131:472–476.

4 Roepman P, Kemmeren P, Wessels LF, Slootweg PJ, Holstege FC: Multiple robust signatures for detecting lymph node metastasis in head and neck cancer. Cancer Res 2006;66:2361–2366.

5 de Bondt BJ, Stokroos R, Casselman JW, Van Engelshoven JM, Beets-Tan RG, Kessels FG: Clinical impact of short tau inversion recovery MRI on staging and management in patients with cervical lymph node metastases of head and neck squamous cell carcinomas. Head Neck 2009;31:928–937.

6 Wensing BM, Vogel WV, Marres HA, et al: FDG-PET in the clinically negative neck in oral squamous cell carcinoma. Laryngoscope 2006;116:809–813.

7 van den Brekel MW, Castelijns JA, Reitsma LC, Leemans CR, van der Waal I, Snow GB: Outcome of observing the N0 neck using ultrasonographic-guided cytology for follow-up. Arch Otolaryngol Head Neck Surg 1999;125:153–156.

8 Hodder SC, Evans RM, Patton DW, Silvester KC: Ultrasound and fine needle aspiration cytology in the staging of neck lymph nodes in oral squamous cell carcinoma. Br J Oral Maxillofac Surg 2000;38:430–436.

9 Borgemeester MC, van den Brekel MW, van Tinteren H, et al: Ultrasound-guided aspiration cytology for the assessment of the clinically N0 neck: factors influencing its accuracy. Head Neck 2008;30:1505–1513.

Prof. Dr. Michiel W.M. van den Brekel

Department of Head and Neck Surgery

and Oncology

Netherlands Cancer Institute/Antoni van

Leeuwenhoek Hospital and

Academic Medical Center Amsterdam

Institute of Phonetic Sciences ACLC

University of Amsterdam

Plesmanlaan 121

NL-1066 CX Amsterdam (The Netherlands)

E- Mail m.vd.brekel@nki.nl