Effect of gap on treatment outcome in patients with supraglottic laryngeal cancer

Local tumour control in 248 patients squamous cell carcinoma of the supraglottic larynx has been examined in relation to the occurrence of unplanned gaps during radiation therapy, independent of its reason. 33% of patients has no gap, 67% suffered from gap, 46% of them had a single gap while 54% had multiple gaps. Data were subjected to uni-and multivariate analysis. The following conclusion were drawn: [1] The presence of gap has a detrimental effect on both local tumour control and overall survival which becomes more evident with increase in the gap number and duration. [2] Gap position is an important prognostic factor. A lower local tumour control was noticed in patients having early gap, during the first two weeks of therapy. Patients with gap in the middle two weeks of therapy had higher local control. A gap later than the fourth week of therapy still accompanied with a drop in local control. [3] The effect of early gap on the local control is significantly accentuated by the presence of latent period between surgery and start of radiotherapy. [4] The combined effects of gap, its multiplicity and duration on prolongation of the overall treatment time is adversely affecting the local control of advanced T3-T4 lesions than early T1-T2 lesions. A general stategy for radiation therapy of supraglottic cancer, should be to deliver the planned radiation dose without undue interruptions, as early as possible in post-operative therapy, in the shortest time and within the tolerance of normal tissues