Treatment results of stage I and II oral tongue cancer with interstitial brachytherapy: maximum tumor thickness is prognostic of nodal metastasis.

Abstract

To evaluate the prognostic importance of T classification and maximum tumor thickness (MTT) on the treatment results of Stage I and II oral tongue cancer treated with interstitial brachytherapy. Between January 1981 and December 1993, 173 cases were eligible for this retrospective analysis. Of 173 patients, 75 were classified as Stage I and 98 as Stage II: maximum tumor length ranged from 6 to 40 mm. MTT, which ranged from 2 to 38 mm, was measured with ultrasonography and/or palpation. Brachytherapy was performed with iridium hairpins or radium needles following external irradiation in 66 patients, or exclusively in 107 patients. The 5-year local recurrence rates were Stage I, 7%; Stage II, 22%; MTT < 8 mm, 8%; and MTT > or = 8 mm, 28%. The 5-year regional recurrence rates were Stage I, 15%; Stage II, 29%; MTT < 8 mm, 18%; and MTT > or = 8 mm, 31%, respectively. The 5-year local recurrence rates of the patients with Stage I and MTT < 8 mm of the brachytherapy only group were significantly better than those of Stage II and MTT > or = 8 mm (5% and 6% vs. 16% and 24%). The 5-year regional recurrence rates of the patients with Stage I and MTT < 8 mm of the brachytherapy-only group were significantly better than those of Stage II and MTT > or = 8 mm (14% and 16% vs. 34% and 46%). There was no significant difference in the 5-year regional recurrence rates between the two groups of Stage I and Stage II, MTT < 8 mm. However, there was a significant difference in the 5-year regional recurrence rates between the two groups of MTT > or = 8 mm (p < 0.005). For patients with Stage I and II oral tongue cancer, tumor thickness as well as T classification were prognostic for nodal metastasis and prognosis. Patients with MTT > or = 8 mm are more likely to fail in the neck region. These findings suggest that MTT should be considered along with T stage in determining strategies for Stage I and II oral tongue cancer.