The prognostic and staging implications of bone invasion in oral squamous cell carcinoma

Abstract

BACKGROUND: A study was undertaken to determine whether bone invasion is an independent prognostic factor in oral squamous cell carcinoma (SCC) after taking into account the extent of bone invasion. METHODS: The study was a retrospective review of 498 patients with oral SCC undergoing surgery with curative intent, 102 of whom had pathologically proven bone invasion. Bone invasion was categorized as absent, cortical, or medullary and tested for association with disease control and survival. RESULTS: After adjusting for potential confounding factors in multivariate analysis, there was no association between cortical invasion and overall (P ¼ .48) or disease-specific survival (P ¼ .63). In contrast, medullary invasion was an independent predictor of reduced overall (hazard ratio [HR], 1.9; 95% confidence interval [CI], 1.2-3.1; P ¼ .006) and disease-specific survival (HR, 2.1; 95% CI, 1.2-3.6; P ¼ .01), and this appeared to result from an increased risk of distant metastatic failure (P ¼ .037) rather than local (P ¼ .51) or regional recurrence (P ¼ .14). Within the subset of patients with medullary invasion, survival differed significantly according to tumor size (P ¼ .029). CONCLUSIONS: Patients with oral SCC and bone invasion have widely variable outcomes depending on the depth of bone invasion and tumor size. The results suggest that the current American Joint Committee on Cancer staging system, which classifies all tumors invading through cortical bone as T4, has limited prognostic utility. The authors recommend a revision of the T staging system such that tumors are classified as T1 to T3 based on size and then upstaged by 1 T stage in the presence of medullary bone invasion. Cancer 2011;117:4460-7.

Close margin alone does not warrant postoperative adjuvant radiotherapy in oral squamous cell carcinoma

“…We previously reported that patients who have T4 oral SCC with medullary invasion have significantly decreased OS and DSS because of distant, rather than locoregional, failures. 24 This study includes a subgroup of patients who had previously been diagnosed with and undergone treatment for another head and neck SCC, including radiotherapy. We have not excluded these patients, because the effect of their prior treatment on their outcome in this study is not known.…”

Potential molecular targets for inhibiting bone invasion by oral squamous cell carcinoma: a review of mechanisms

“…The 5-year disease-specific survival rate was 61% for patients with mandibular invasion, compared to 80% for those without. Recently, Ardalan and his colleagues published another retrospective review, with a larger sample of 498 patients, 102 of whom had histologically proven invasion of bone at initial surgery [13]. After adjusting for other factors in a multivariate analysis, medullar invasion was the only independent predictor of reduced survival.…”

Primary Tumor Staging for Oral Cancer and a Proposed Modification Incorporating Depth of Invasion

“…There is some evidence to suggest that the prognosis of T4 tumors with bone invasion varies substantially according to tumor size, and small primary tumors with bone invasion are associated with a relatively favorable prognosis that does not warrant T4 classification. 32,33 Further study is required to confirm whether incorporation of DOI data is necessary for tumors in these subsites, particularly after reclassification of tumors with bone invasion based on consideration of tumor size. This study has several limitations.…”