Page 49 - Read Online

Galli et al. J Cancer Metastasis Treat 2022;8:48 https://dx.doi.org/10.20517/2394-4722.2022.19 Page 11 of 14

[18]
cohort of patients with recurrent LSCC undergoing STL after (C)RT . To our knowledge, a consensus
regarding radiological scoring criteria for suspicious LN has not been published. Our results for PET/CT
show an excellent NPV of 96.9%. The role of MRI in the re-staging of the neck in patients with recurrent
LSCC seems largely underexplored in previous studies. Similar to PET/CT, our results showed MRI to have
a very good NPV (94.1%). The rationale for both modalities is that PET/CT is a staging method for the neck
as well as for distant metastases. Nevertheless, it provides limited additional information over other imaging
techniques with regard to the primary tumor. MRI complements PET/CT for morphological
characterization, and thus staging of the primary, and can equally help with neck staging given that the
main downside of PET/CT in the irradiated neck is the high rate of false positives. We therefore
recommend performing both imaging modalities before committing to a salvage procedure. In the future,
the diagnostic yield of novel combined imaging modalities such as PET/MRI should be investigated in this
field.

While ultrasound and fine needle aspiration (FNA) cytology have been routinely and consistently used for
assessing lymph node status at our institution over the last decade, they are mostly used in the context of
follow-up, not to confirm radiographically suspicious LNs in the neck. In the literature, assessment of nodal
status with ultrasound of recurrent laryngeal cancer previously treated with (C)RT has not been evaluated
by any study in the past 10 years. However, it is possible to confirm radiographically suspicious LN
metastases with FNA. In the study of Fleischman et al., specificity of up to 100% was found for FNA
[37]
performed to confirm persistent head and neck SCC after CRT in neck LNs . However, FNA harbors a
non-negligible false negative rate of up to 33% , and LN metastases will be missed if ND is omitted.
[38]
Salvage total laryngectomy has a high adverse event rate compared with primary total laryngectomy, with
[39]
this being reported to be up to 67.5% in a review by Hasan et al. . Likewise, our cohort had a high early
adverse event rate (grades I-V, Clavien-Dindo score) of 51.4%. Hasan et al. showed that concomitant ND is
[39]
a risk factor for complications in STL . Therefore, in radiologically staged cN0 necks, ND should be
discussed in multidisciplinary team meetings and may be omitted to avoid postoperative complications.

There are several limitations to our present study, including the modest cohort size and the retrospective
study design. Moreover, the low disease prevalence influences the application of Bayes’ theorem and limits
the results of our study. Furthermore, routine histopathological assessment of neck specimens, as performed
in our patients, may overlook up to 15% of micrometastases, and the real number of occult metastases may
be higher .
[40]

It should be noted that existing cohorts tend to be small, given the need to select a homogeneous
population. Furthermore, although our findings suggest that occult neck nodal metastatic disease is
uncommon in patients undergoing STL with negative nodal stage on MRI and/or PET/CT, they do not
exclude the possibility that there may be a subset of patients at increased risk of harboring metastases. The
small number of pN+ cases in our series precluded meaningful evaluation of such risk factors. By contrast,
the widespread use of MRI and/or PET/CT likely facilitated a high degree of accuracy and consistency in
preoperative staging of recurrence in the neck.

CONCLUSION
We found rates of occult neck node metastasis of 3.2%, 6.1%, and 3.8% in recurrent LSCC re-staged with
PET/CT, MRI, and MRI + PET/CT together. High negative predictive values were found for both
modalities. In cases in which preoperative MRI or PET/CT suggests nodal metastases, ND is clearly
indicated. In contrast, in patients with a negative nodal stage on MRI and/or PET/CT, omitting the ND