13 Head and Neck - Oropharynx

Head and Neck - Oropharynx

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 15/02/2021

treatment is considered while for advanced disease combined chemoradiation is the standard of care. Radiation therapy can be EBRT alone or combined with BT. The role of surgery in oropharyngeal cancers has been controversial due to treatment relatedmorbidity [6]. However with the advent of robotic surgery there is a resurgence in the surgical option for early stage disease [7]. Surgery vs Brachytherapy Brachytherapy results in excellent organ and function preservation when compared to surgery. Levendag et al studied 248 patients who were treated with either brachytherapy or surgery for oropharyngeal cancer T1-3,N0/+[6]. Those who were suitable for BT were considered for EBRT to a dose of 46Gy in 23 fractions followed by BT and unsuitable patients were considered for surgery followed by postoperative RT. The 5 year local control (LC) for both BT and surgery were 88%. The 5 year overall survival (OAS) was 67% for BT vs 57% for surgery. The significant late sequelae in BT vs surgery were ulceration 39% vs 7% (p=0.001) and trismus 1% vs 21% (p=0.005). There was no statistically significant difference in the quality of life scores between the two groups. LDR LDRBT is awell-establishedmodality of treatment for oropharyngeal cancer (Table 3). Lusichini et al reported outcomes of 108 patients treated with LDR BT for oropharyngeal cancers [40]. The LC rates in their series were 85% for T1 and 50% for T2 and 69% for T3. Similar outcomes were also reported in other studies [41,42]. Crook et al observed a dose response relationship with LC of 79% with doses of ≥ 75Gy vs 50% for doses ≤ 70Gy [41]. Puthawala et al treated 70 patients of base of tongue with EBRT and BT [34]. The dose delivered for T1-2 was 20-25Gy and for T3-4 around 30-40Gy after EBRT. One of the largest series of LDR for velotonsillar region is by Pernot et al in which they studied 361 patients [35]. The LC rate was 80% at 5 years in their series. There was a statistically significant difference in the LC rates in patients who had node negative disease (LC=83%) as compared to node positive patients (55%, p=0.002). Similar outcomes were also shown in other studies [43,44]. PDR There is relative lack of data for the use of PDRBT for oropharyngeal cancers (Table 4). Haddad A et al in a case control study compared 36 patients with oral cavity and oropharynx tumours treated with PDR BT with 72 patients treated with LDR BT [45]. The 3 year actuarial locoregional recurrence free survival was 94% for PDR and 97% for LDR. The soft tissue necrosis rates were 19% in PDR and 31% in LDR. The osteoradionecrosis rates were 3% in PDR and 7% in LDR. This suggests that PDR results in similar LC rates as compared to LDR with lower toxicity due to the possibility of dose distribution modulation. One of the largest studies of oropharyngeal BT using PDR BT is by the Rotterdam group[16]. They studied 167 patients with oropharyngeal cancers who were treated with IMRT to a dose of 46Gy followed by PDR BT to a mean total dose of 22Gy delivered in 8 fractions per day at 3 hourly intervals. At a median follow up of 56 months, the 5 year actuarial LC rate was 94%. Five year DFS and OAS were 84% and 74% respectively. They observed grade 3 ulceration in 3% patients requiring hyperbaric oxygen therapy.

Figure 28: Removal of patients treated with non-looping loop technique (Bhadrasain et al)

As majority of the experience in head and neck BT is with LDR, typically dose equivalent of the same are considered while treating with HDR or PDR. Doses may also be documented in terms of EQD2 as in other sites. However in head neck cancers the EQD2 calculations of the radical and boost doses appear much lower and hence should be used very cautiously.

11. MONITORING AND POSTTREATMENT CARE

During treatment dressings should be checked daily. Before each treatment catheters should be checked for possible loosening and movement. Maintaining good oral hygiene is extremely important during the treatment. Patients are advised to use salt soda gargles at frequent intervals. Patients receive feeding via a nasogastric tube and pain medications, steroids in tapering doses and antibiotics as and when necessary. Removal Because of the risk of bleeding catheters should be removed in the operating theatre in the presence of at least two persons. An intravenous line should be secured before the removal. Silk threads which are tied to the closed end are very useful for removal of the implant. The tubes are cut at the open ends in the neck and are pulled through the mouth using the silk threads (Figure 28). If there is any bleeding bimanual compression should be used for 5-10 minutes. In the majority of cases bleeding stops with this procedure. The mouth is cleaned with cold saline gargles and a tight dressing with antiseptic is put on the neck. The patient is advised to take a soft diet after a few hours. Once comfortable with oral feeds the nasogastric tube is removed. The neck dressing is also removed in a day or two depending on the rate of healing. Mucositis develops 1 - 2 weeks after BT.The acute mucosal toxicity is maximal at 3 - 4 weeks, and heals progressively in 5 - 8 weeks. This is managed with mouth care, mouth washes and analgesics.

12. RESULTS

Radical radiotherapy remains the mainstay of treatment of oropharyngeal cancer. For early stage disease single modality