Small oral tongue cancers (≤ 4 cm in diameter) with clinically negative neck: from the 7th to the 8th edition of the American Joint Committee on Cancer

Abstract

One of the main changes in the 8th edition of the American Joint Committee on Cancer (AJCC) for staging of oral cancer is the inclusion of depth of invasion (DOI) in the T category. However, cancers in different oral subsites have variable behavior, with oral tongue squamous cell carcinoma (OTSCC) being the most aggressive one even at early stage. Thus, it is necessary to evaluate the performance of this new T category in homogenous cohort of early OTSCC. Therefore, we analyzed a large cohort of patients with a small (≤ 4 cm) OTSCC to demonstrate the differences in T stage between the AJCC 7th and 8th editions. A total of 311 early-stage cases (AJCC 7th) of OTSCC were analyzed. We used 5 mm and 10 mm DOI for upstaging from T1 to T2 and from T2 to T3 respectively, as in the AJCC 8th. We further reclassified the cases according to our own proposal suggesting 2 mm to upstage to T2 and 4 mm to upstage to T3. According to AJCC 7th, there were no significant differences in the survival analysis. When we applied the 8th edition, many cases were upstaged to T3 and thus associated with worse disease-specific survival (HR 2.37, 95% CI 1.12-4.99) and disease-free survival (HR 2.12, 95% CI 1.09-4.08). Based on our proposal, T3 cases were associated with even worse disease-specific survival (HR 4.19, 95% CI 2.27-7.74). The 8th edition provides better survival prediction for OTSCC than the 7th and can be further optimized by lowering the DOI cutoffs.

The 8th Edition of the American Joint Committee on Cancer (AJCC8) Staging Manual: any improvement in the prognostication of oral tongue cancer?

“…Now, in the AJCC8, the superficial tumor is classified as T1, while the deep tumor (>10 mm) is classified as T3, although both have the same dimension of ≤2 cm. This remarkable change in the classification category of small OTSCC was noted in our recent study (6).…”

“…According to the evaluation with AJCC8, 25 cases were reclassified, and in particular, the use of ENE in pN classification identified patients with worse diseasefree survival and overall survival (P<0.05). We also recently re-classified our multicenter cohort of 311 early-stage cases (cT1-2N0, based on the 7th edition) according to the AJCC8, and compared the prognostic capacity of both systems (6). We noted that many cases were upstaged (even from cT1 to cT3) and were associated with worse diseasespecific survival and disease-free survival (6).…”

“…We also recently re-classified our multicenter cohort of 311 early-stage cases (cT1-2N0, based on the 7th edition) according to the AJCC8, and compared the prognostic capacity of both systems (6). We noted that many cases were upstaged (even from cT1 to cT3) and were associated with worse diseasespecific survival and disease-free survival (6). Similarly, in a cohort of 298 OSCC cases, upstaging was common in pT and in pN classifications, and those upstaged cases associated with poorer prognosis (7).…”

Depth of invasion for prognostic stratification in oral cavity cancer: do we need further validation?

“…In a recent work, in fact, Almangush et al reclassified 311 early-stage tongue SCC, suggesting a 2 mm DOI cut-off to upstage to T2 and a 4 mm threshold for upstaging to T3. According to their proposal, T3 disease had an even worse DSS, but the difference between T1 and T2N0 was still not significant (11).…”

“…By contrast, retrospective validation studies showed a similar DSS for T1 and T2N0 disease as identified by the last edition of the TNM staging system (4,10-12). This was another effect of the staging migration described above: since survival of T2N0 tongue SCC improved as more invasive cancers were clustered in Stage III disease, the existent gap between T1 and T2N0 scenarios was reduced in a parallel way (4,(10)(11)(12)17). At the same time, small cancers (<2 cm), infiltrating in depth more than 5 mm, migrated from T1 to T2.…”