|LETTER TO EDITOR
|Year : 2017 | Volume
| Issue : 2 | Page : 93-94
Commentary on 8th Edition of tumor node metastasis for staging of cancers of the oral cavity
Abhishek Chatterjee, Sarbani Ghosh Laskar
Department of Radiation Oncology, Tata Memorial Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||22-Jan-2018|
Dr. Sarbani Ghosh Laskar
Department of Radiation Oncology, Tata Memorial Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Chatterjee A, Laskar SG. Commentary on 8th Edition of tumor node metastasis for staging of cancers of the oral cavity. J Head Neck Physicians Surg 2017;5:93-4
|How to cite this URL:|
Chatterjee A, Laskar SG. Commentary on 8th Edition of tumor node metastasis for staging of cancers of the oral cavity. J Head Neck Physicians Surg [serial online] 2017 [cited 2019 Sep 15];5:93-4. Available from: http://www.jhnps.org/text.asp?2017/5/2/93/223766
Oral cavity cancer remains predominantly a disease of the developing world. The proposed tumor-node-metastasis (TNM) staging for the American Joint Committee on Cancer (AJCC) 8 poses major challenges in its widespread applicability in the nations where this disease is rampant.
First, the oral cavity is an extremely heterogeneous site. Tongue and floor of mouth cancers are very different from gingival–buccal complex cancers in their biology, behavior, and patterns of spread. The proposed TNM classification remains insensitive to this distinction.
The most distinguishing feature of the new T-classifier is the usage of depth of infiltration (DOI). There are several issues with the same. The data justifying the usage of DOI as an omnipotent arbiter of T stage is culled mainly from series studying tongue and floor of mouth cancers,, where indeed an increased DOI increases the chances of lymph nodal spread. The comprehensive analysis by Ebrahimi et al. do not allude to the site-wise distribution of cases. The same is not true for gingival–buccal cancers. Moreover, DOI can be influenced by subjectivity and is often not reported in routine pathology.
The N classifier has accorded a lot of importance to the presence of extracapsular extension (ECE), which is known to confer an adverse prognosis. However, ECE is mainly a pathological finding. We feel that any staging for oral cavity cancer (a site easily accessible to examination) should incorporate elements which are easily assessable clinicoradiologically. A contrast-enhanced computed tomography scan of the face and neck, which is the most commonly used cross-sectional imaging modality has been shown to have poor sensitivity in detecting ECE. Clinical estimation of ECE would be even more fraught with error. The cN stage may not be reproducible. One of the utilities of the TNM is to be able to carry out multi-institutional studies. This aspect of the cN staging may be fraught with a lot of subjectivity, making interobserver comparisons unreliable.
Extensive soft-tissue infiltration is typically seen in locally advanced cancers of the oral cavity. Such infiltration has also been found to confer a poorer disease-free interval. Deep infiltration of the adjacent soft tissues is an easily recognizable feature and as such could be taken cognizance of in staging.
We tested the changes in staging between the 7th and 8th edition of the AJCC staging on 100 patients accrued on a prospective randomized trial of adjuvant therapy in locally advanced oral cavity cancer. The dataset predominantly comprised of gingivobuccal cancers (72 patients) with 27 patients of cancer of the oral tongue and floor of mouth.
N-Stage migration occurred in 58 patients, all being upstaged. The most common stage migration occurred from N2b (AJCC 7) to N3b (AJCC 8) in 34 patients, followed by migration from N2c (AJCC 7) to N3b (AJCC 8) in 9 patients. However, at a median follow-up of 20.5 months, the overall survival was 58.3 months for the patients with N2b disease (AJCC 7), which was similar to the survival of patients restaged as N3b (AJCC 8). The migration in stage did not lead to worsening of survival. Whether this is a true reflection of stage migration or the effect of selection bias would remain a point of debate.
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Conflicts of interest
There are no conflicts of interest.
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