The radiation oncology reference committee (RC) supported the publication of this protocol on the basis of the information summarised below. The RC was most strongly influenced by the population studies of Mahmood et al. 2011 and Safdieh et al. 2017 and cohort studies and case series of et al. 2005, Tehaard et al. 2004 and Chen et al. 2006 and 2007.rrrrrr Retrospective data suggests that adjuvant post operative RT improves both local control and survival for selected patients with salivary gland tumours.r In patients with microscopic disease present at or close to the surgical margin, the use of postoperative RT rather than surgery alone reduced the incidence of local recurrence from 54% to 14%.r Similarly, for patients with stage III and IV disease, the five-year local control rate and cause-specific survival were both 51% with adjuvant RT and 17% and 10% with surgery alone.r
Mahmood et al. 2011 reported on 2170 patients from the SEER database from 1988-2005.r Multivariate analysis showed improved survival with adjuvant radiotherapy (HR 0.76, 95% CI 0.65-0.89, p<0.01).
Terhaard et al. 2004 reported on a retrospective analysis of 538 patients treated for major salivary gland tumours, post operative radiotherapy was shown to improve 10 year local control compared with surgery alone.r Local and regional control was significantly higher for the group receiving combined treatment compared to those receiving surgery alone. In multivariate analysis the relative risk for surgery alone compared with combined treatment was 9.7 for local recurrence and 2.3 for regional recurrence.
Mendenhall et al. 2005 reported on 224 patients treated with surgery + post op RT (n=160) vs RT alone (n=64).r The 10 year local control rate for the surgery and post op RT group was 96% for T1-3, and 70% for T4 vs 75% and 21%, respectively for surgery alone. Multivariate analysis of local control revealed that T classification (p<0.0001) and treatment group (p<0.0001) significantly influenced this endpoint. The 10 year overall survival rates also favoured surgery and post op RT group (27%) vs RT alone (21%) in patients with T4 tumours.
In the latest attempt Safdieh et al. 2017 investigated the characteristics, outcomes and benefits of adjuvant radiotherapy for patients diagnosed with malignant salivary gland tumours using the National Cancer Database (NCDB) between 2004 and 2012.r There was a significant improvement in overall survival associated with those receiving post operative RT. The 5 year and median overall survival rates were 56% and 73.1 months, respectively, in the post operative RT group versus 50.6% and 61 months in the no-radiation group (P<0.001). On multivariable analysis, the usage of postoperative radiation (hazard ratio [HR], 0.79; 95% CI, 0.71-0.87; P<.001) was associated with improved survival.
© Otolaryngology-Head and Neck Surgery 2017
Local control rates, and survival ratesr
© Cancer 2005
Management of neck nodes
The management of the neck in patients with salivary gland tumours remains controversial. The rate of occult disease had been reported to range from 8-19% prompting most treatment centres to recommend the use of elective neck dissection for patients with high grade histology or large (> 4cm) tumours.r
Peters et al. 2010 reported on the impact of radiotherapy quality on patient outcomes in a large international phase III trial (TROG 02.02).r In patients with major deficiencies in their radiotherapy treatment plan there was a significantly inferior outcome; 2-year overall survival of 50% vs 70%; hazard ratio (HR), 1.99; P< .001; and 2-year freedom from locoregional failure, 54% v 78%; HR, 2.37; <P .001, respectively. These results show the critical importance of radiotherapy quality on outcome of chemoradiotherapy in locally advanced head and neck cancer.