Unilateral IMRT Is Effective in Palatine Tonsillar Cancer

October 2, 2017

Use of unilateral intensity-modulated radiotherapy reduced acute toxicities and maintained oncologic outcomes compared with bilateral IMRT in patients with lateralized palatine tonsillar cancer, according to the results of a new study.

Use of unilateral intensity-modulated radiotherapy (IMRT) reduced acute toxicities and maintained oncologic outcomes compared with bilateral IMRT in patients with lateralized palatine tonsillar cancer, according to the results of a study published in Cancer.

“Unilateral neck IMRT in patients with lateralized tonsillar cancer and N0 to N2b disease did not appear to compromise locoregional control, and was associated with a lower rate of acute toxicity and use of G-tubes, and better patient-reported quality of life compared with bilateral IMRT,” wrote Re-I Chin, BA, of the department of radiation oncology at Washington University School of Medicine in St. Louis, and colleagues. “The results of the current study support the efficacy and benefit of unilateral IMRT in properly selected patients with lateralized palatine tonsillar cancer.”

According to the study, radiotherapy in patients with head and neck cancer is a balance of maximizing cure while minimizing adverse events. Advancements in radiotherapy such as IMRT have allowed for a reduction in the treatment fields. Specifically, unilateral neck radiotherapy has been shown to decrease toxicity compared with bilateral therapy.

In this study, Chin and colleagues compared bilateral and unilateral IMRT in 154 patients with lateralized palatine tonsillar cancer. Patients were treated from 1997 to 2013, and data were collected prospectively from 2005 to 2013 and retrospectively prior to 2005.

There were three groups of patients: Group 1 included 48 patients with lateralized primary and N0 to N2b disease who underwent unilateral IMRT. Group 2 included 59 patients with lateralized primary and N0 to N2b disease who underwent bilateral IMRT. Group 3 included 47 patients with nonlateralized primary and N2c or N3 disease who received bilateral IMRT.

After a median follow-up of 5.5 years, the 5-year locoregional control rates were 100%, 96%, and 94% for groups 1, 2, and 3.

Multivariate analysis showed that older age at the time of diagnosis was the only factor significantly associated with locoregional control (hazard ratio [HR], 1.19; 95% CI, 1.01–1.43; P = .048).

During the study follow-up period, 27% of patients died. The 5-year overall survival rates were also similar in all 3 groups (85%, 79%, and 76%, respectively). No contralateral neck recurrences were noted among those patients treated with unilateral IMRT.

Finally, unilateral treatment reduced acute toxicity. There were lower rates of grade 3 mucositis, grade 1 to 3 xerostomia, and grade 3 weight loss among patients treated unilaterally.

“Importantly, the need for a reactive and long-term G-tube also was found to be reduced,” the researchers noted.

About half of patients had quality-of-life data available. Although baseline scores were not significantly different between patients treated unilaterally compared with bilaterally, after treatment, quality of life was superior in patients in the unilateral group compared with the bilateral group.