LONDON – Nonglottic cancer and the presence of dysphagia before treatment are highly predictive for severe acute and late swallowing difficulties after radiotherapy for head and neck cancer, according to new data from the DAHANCA 6&7 randomized trial.
Patients with nonglottic cancer were more likely than those with other cancer types to experience severe dysphagia at both 6 and 12 months. Dysphagia before treatment was also associated with both acute and late severe swallowing difficulties.
"The peak incidence of dysphagia is seen during the first 6 months after radiotherapy," Hanna Rahbek Mortensen, Ph.D., reported in an analysis of the DAHANCA (Danish Head and Neck Cancer Group) 6&7 trial findings at the European Society for Therapeutic Radiation Oncology Anniversary Congress.
"After 1 year, however, there is no further increase in severity or prevalence," said Dr. Mortensen of the department of experimental clinical oncology at Åarhus (Denmark) University Hospital.
The trial involved 1,478 patients with squamous cell carcinomas of the glottic larynx, supraglottic larynx, pharynx, or oral cavity who were who were treated with five or six weekly fractions of radiotherapy in 1992-1999. The total dose of radiotherapy delivered was 66-68 Gy in 33-34 fractions.
Efficacy data from the trial have already been published; they showed improved disease-specific but not overall survival of five vs. six fractions of radiotherapy (Lancet 2003;362:933-40).
The aim of the present analysis was to use prospectively collected data from the trial to determine whether any factors could be used to establish which patients may be more likely than others to experience dysphagia following treatment.
"Dysphagia is a common and debilitating side effect of radiotherapy, leading to malnutrition, aspiration, and reduced quality of life," Dr. Mortensen explained. The side effect can be graded using a 5-point scale, with a score of 0 signifying no dysphagia and a score of 3 or 4 indicating considerable or severe dysphagia despite the ingestion of a liquid-only diet.
In all, 1,422 (96%) patients experienced acute dysphagia, including severe grade 3/4 dysphagia in 47% and 38% of those receiving accelerated or conventional radiotherapy, respectively. The two factors most predictive for severe dysphagia at 6 months were nonglottic cancer (odds ratio, 6.73 vs. other sites; P less than .0001) and a baseline dysphagia score of 2-4 vs. 0-1 (OR, 2.11; P =.004).
Odd ratios for other factors predictive for acute – but not late – dysphagia were 1.92 for any (N1-N3) vs. no (N0) nodal involvement (P less than .001), 1.82 for the use of accelerated (six weekly fractions) vs. conventional (five weekly fractions) radiotherapy (P less than .001), and 1.58 for stage T3-T4 vs. stage T1-T2 cancer (P = .02).
After 5-years of regular follow-up, late dysphagia had occurred in 1,205 patients (81%), with grade 3 severity in 24% and grade 4 in 23%. Factors that were predictive for late severe dysphagia that occurred 12 months after radiotherapy were, again, nonglottic cancer (OR, 8.25; P less than .0001) and a baseline dysphagia score greater than 1 (OR, 2.57; P less than .002). Late (T3-T4) tumor stage was also predictive (OR, 1.86; P = .03).
"Predictive factors have been identified to characterize patients at risk of developing acute and late dysphagia," Dr. Mortensen said. These factors may be useful to identify patients who could perhaps benefit from prophylactic measures against swallowing dysfunction.
The DAHANCA 6&7 trial was supported by the Danish Cancer Society, Åarhus University Hospital, Copenhagen University Hospital, Herlev (Denmark) Hospital, Odense (Denmark) University Hospital, and Aalborg (Denmark) Hospital on behalf of DAHANCA. Dr. Mortensen had no personal financial disclosures to declare.