Interstitial irradiation for carcinoma of the tongue and floor of mouth: Royal Marsden Hospital Experience 1970-1986.

One hundred and forty nine patients with carcinoma of the tongue or floor of mouth were treated with interstitial irradiation (+/- external beam therapy) using caesium needles or iridium wires between 1970 and 1986. Multivariate analysis showed the main predictors of outcome to be tumour stage, site and histology. Caesium and iridium techniques gave similarly good local control rates of 90% at 5 years for T1 and T2 tumours when used as the standard departmental method. Local failure was shown to have a major impact on the risk of dying from disease and elective neck irradiation (ENI) conferred a favourable benefit on neck control and survival provided the primary site was controlled. Patients less than 40 years of age appeared to have an unfavourable prognosis. Radical irradiation including interstitial techniques gives excellent results in early oral cancer and is the treatment of choice for T2 tumours. We recommend elective neck irradiation in patients at high risk of developing lymph node metastases.