2018-19 Section 7-Neoplastic and Inflammatory Diseases of the Head and Neck eBook

J. García et al. / Oral Oncology 70 (2017) 29–33

Table 4 Five-year cause-specific survival according pN category in both 7th ed. TNM and 8th ed. TNM.

7th ed. TNM 5-year surv. (CI 95%)

P

8th ed. TNM 5-year surv. (C I95%)

P

pN0 pN1 pN2 pN3

83.1% (79.8–86.4%) 69.2% (61.6–76.8%) 35.5% (30.1–40.9%) 21.8% (7.7–35.9%)

0.0001

83.1% (79.8–86.4%) 70.5% (62.1–78.9%) 53.3 (45.3–61.3%) 23.8 (18.2–29.4%)

0.0001

any patient. The new pN3a category is formed by patients with very large nodal metastasis (more than 6 cm) without ECS. The vast majority of lymph node metastasis this size show ECS in patholog- ical analysis. So the potential number of patients included in the pN3a category is very limited. In our series, all the patients with nodal metastasis larger than 6 cm showed ECS, so none could be included in the pN3a category. The inclusion of ECS as a pathological criterion in the classifica- tion of the neck nodes implies the need to systematically include information about its presence in the pathological records of neck dissections. However, the pathological criteria for ECS are not well established. Van den Brekel et al. [12] found a low level of intraob- server and interobserver agreement in a study evaluating the assessment of ECS in lymph node metastasis. Given its prognostic significance, the authors called for accepted reproducible histopathological criteria for the assessment of ECS in the neck dissections. Moreover, one of the difficulties of using the clinical classifica- tion of lymph nodes (cN) in the new 8th ed. TNM is the evaluation of ECS. This will largely depend on the imaging studies. As for pathological ECS, there is no consensus on imaging criteria for ECS. Most authors consider capsular contour irregularity, poorly defined nodal margins, and infiltration of adjacent fat planes [12–19] as suggestive signs of ECS in imaging studies. Additionally, central node necrosis [16,17] and nodal capsular enhancement [12,14,15] have been also included as predictors for the presence of ECS. More recent studies using PET-CT in several head and neck subsites have described a relationship between maximum stan- dardized uptake values (SUV max ) and ECS [20–23] . Su et al. [24] published a metanalysis studying the reliability of imaging studies in the diagnostic of ECS in HNSCC patients. The pooled data of the 15 studies included in the metanalysis yielded a mean sensitivity/ specificity for CT of 0.77/0.85, for MRI of 0.85/0.84, and for PET/CT of 0.86/0.86. However, the diagnostic performances of the present imaging modalities show important variations in sensitivity and specificity between studies, probably due to significant variations in the radiological criteria of ECS. Given the relevance of ECS in the new edition of the TNM Classification, it would be necessary to clarify and standardize the diagnostic criteria of ECS in imaging studies. One of the strengths of our study is the objective evaluation of the quality of the classifications. The 8th ed. TNM improved the dif- ferences in survival among pN categories as well as the distribution of the number of patients per category when compared with the 7th ed. TNM. This study is a retrospective evaluation of a series of consecu- tive patients treated in a single institution. This limits the extent of our conclusions and call for further studies to validate the prog- nostic capacity of the inclusion of ECS as a pathological criterion in the evaluation of neck dissections in the new edition of the TNM Classification.

survival curves (hazard discrimination), and a more balanced dis- tribution of the number of cases (balance). The differences between both editions of the TNM classification were basically produced by the migration of 58.4% of the patients classified as pN2 in the 7th ed. TNM to the new pN3b category. This migration was produced by the inclusion of ECS as an unfavorable prognostic criterion. This new concept allows the division of the old pN2 category into two groups with a clear difference in progno- sis. As shown in Fig. 2 B, patients in the 7th ed. TNM pN2 category with ECS show a significantly worse cause-specific survival than those without ECS. Interestingly, patients with limited nodal disease classified as pN1 in the 7th ed. TNM do not show a significant alteration in sur- vival related to ECS. In our series, survival for patients with one iso- lated node up to 3 cm without ECS was similar as for those with ECS. However, it must be remembered that patients with ECS received postoperative radiotherapy or chemoradiotherapy. Green- berg et al. [10] found similar results and attributed the low impact of ECS in pN1 patients to the high efficacy of the intensification of adjuvant treatments in this group of patients. One of the limitations of the new classification system is the inclusion of a subcategory with a very low probability of including Fig. 2. Results of the reclassification according to the 8th ed. TNM of patients classified as pN1 (Fig. A) or pN2 (Fig. B) with the 7th ed. TNM. Curves represent cause-specific survival.

Conclusion

According to our data, the inclusion of ECS in the pathological classification (pN) of the neck nodes improves the prognostic

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