Use of routine ultrasound-guided fine-needle aspiration cytology to assess the neck in patients with head and neck squamous cell carcinoma.

Abstract

To the Editor: As faithful readers of Head & Neck, we read with great interest the article entitled "Initial staging of the neck in head and neck squamous cell carcinoma: a comparison of CT, PET/CT, and ultrasound-guided fine-needle aspiration cytology'' by Stoeckli et al. We would like to compliment the authors on their large-scale prospective analysis of different imaging modalities for staging neck metastasis in patients with head and neck squamous cell carcinoma (HNSCC). This is a very important issue, and different results and conclusions exist in the literature. In their study, Stoeckli et al concluded that ultrasound-guided fineneedle aspiration cytology (ultrasound-guided FNAC) seems to correlate best with the exact histologic staging and they will always complement CT with ultrasoundguided FNAC to assess patients with HNSCC. However, some details of their use of ultrasound-guided FNAC were not described in the article, and according to their result, the value of routine ultrasound-guided FNAC needs further discussion. In general, pretreatment imaging for HNSCC has 2 purposes. The first purpose is to document the extent of primary tumor and possible neck metastasis. The second purpose is to detect occult neck metastasis and guide further neck management. As mentioned by Stoeckli et al and Grandi et al, the status of the regional lymphatic involvement is considered the strongest prognosticator for HNSCC. Therefore, a sensitive method for detecting occult neck metastasis would be very helpful in determining treatment intensity and posttreatment follow-up. In regard to the documentation issue, it is clear that the extent of the primary lesion usually cannot be well documented by ultrasound images. That should be the reason why Stoeckli et al still routinely use CT or MRI for patients before treatment. According to a meta-analysis conducted by de Bondt et al, CT and MRI have several advantages, including lower interobserver variation, relatively standardized techniques that can be performed at most institutions, ease of interpretation by general radiologists, and less time consumption compared with ultrasound scans and ultrasound-guided FNAC. Therefore, CT and MRI are more commonly used for HNSCC. Under such circumstances, ultrasound-guided FNAC should provide much higher accuracy to stage the neck or much higher sensitivity to detect occult metastasis to justify its routine use. However, the rate of correct staging of the pathologic result of the neck for ultrasound-guided FNAC (69%) was only slightly better than that for CT (62%). Furthermore, the sensitivities of CT and ultrasound-guided FNAC in differentiating N0 from Nþ neck were almost equal (86.9% vs 86.4%). The relative positive predictive value (PPV) of ultrasound-guided FNAC PPV versus the CT PPV was 1.08 (95% confidence interval, 1.00 to approximately 1.17) indicated that these 2 techniques have almost equal PPV. Therefore, we could not find any strong evidence to encourage routine ultrasound-guided FNAC when a CT or MRI has been done. In the article by Stoeckli et al, approximately one third of the patients were incorrectly staged/classified with the selected imaging methods, and none of the imaging modalities is reliable enough to replace elective neck treatment in cN0 necks. In our opinion, elective neck dissection should be encouraged for patients with HNSCC who agree to receive surgical treatment. The real pathologic N classification obtained will facilitate planning of further adjuvant therapy. For patients with clinical N0 neck detected by CT or MRI who refuse elective neck dissection or are considering elective neck irradiation, ultrasound-guided FNAC might have a role in selection of treatment options. However, there is no universal standard for ultrasound-guided FNAC in the literature, and the sensitivity varied widely from 48% to 90%. From the diagnostic criteria of Stoeckli et al, a minimum axial diameter of 7 mm lymph node for level II neck plus many other features of lymph nodes were all aspirated. We would like to know how many lymph nodes on average were histologically checked in clinical N0 necks to detect an occult metastasis in their experience. In conclusion, strong evidence for routine ultrasoundguided FNAC in HNSCC is lacking. The optimum standard diagnostic procedures and aspiration criteria for ultrasound-guided FNAC still need further investigation.