**9. Buried glands**

160 Gastrointestinal Endoscopy

over the guide wire and inflated once in the distal oesophagus. In long segment Barrett's oesophagus several measurements are taken and subsequently, an appropriately sized ablation catheter is selected (based on the smallest oesophageal diameter measurement). The catheter is then passed over the guide wire and positioned at the proximal extent of the Barrett's segment. The endoscope is re-passed to ensure correct positioning of the catheter and the balloon is then inflated and a standardised dose of energy is delivered (which has a power density sufficient to ablate down to the muscularis mucosae, 700-1000µm deep). After a short period of treatment (<5s) the catheter is passed distally to the next portion of the oesophagus to be treated, trying to minimise overlap between zones by endoscopic visualisation. Once the entire Barrett's segment has been ablated the catheter is removed and the endoscope is reinserted in order to debride the ablated mucosa. The procedure is

Complications are rare but include significant bleeding (1-2%), stricture formation (6%) and perforation (very rare). (Shaheen et al., 2009) Repeat OGD is recommended after 2 – 3 months and any residual focal Barrett's oesophagus can then be treated using HALO90 RFA. The only RCT, by Shaheen et al in 2009, demonstrated successful resolution of dysplastic Barrett's oesophagus following treatment with RFA.(Shaheen et al., 2009) Complete eradication of LGD was seen in 90.5% (ablation group) compared to 22.7% (control group) (P<0.001). Complete eradication of HGD occurred in 81.0% (ablation group) versus 19.0% (control group) (P<0.001). RFA also decreased the likelihood of disease progression (3.6% vs.

Recent NICE guidelines (June 2010) recommend that clinicians in the UK consider endoscopic ablation therapy (preferentially RFA) along with EMR, for treatment of HGD

Porfimer sodium photodynamic therapy (PDT) has been approved by the US Food and Drug Administration (FDA) and (provisionally) by NICE for treatment of HGD in Barrett's

The procedure involves systemic (intravenous) administration of a photosensitising agent (porfimer sodium) which is retained selectively by dysplastic cells. After about 48 hours the patient undergoes an upper endoscopy and a laser is used to excite a cytotoxic reaction in dysplastic Barrett's cells, leading to their destruction. There is now strong evidence that PDT can prevent the progression of disease in patients with Barrett's HGD. (Overholt et al., 2007) A five year randomised multicentre trial by Overholt et al demonstrated that PDT was significantly more effective at eradicating HGD than omeprazole only (odds ratio 2±0.7). It also significantly lengthened the time taken to progress to malignancy and reduced the overall risk of malignant progression by half. (Overholt et al., 2007) Following PDT, patients are required to continue life-long surveillance, and repeat ablation may become necessary. Side-effects of PDT include nausea and chest pain in the first day or two after treatment. In the longer term, oesophageal strictures may occur in up to a quarter of patients. Oesophageal perforation has also been described (very rarely). In addition, due to the photosensitising affect of porfimer sodium, patients are required to minimise light exposure

Several trials in Europe have used 5-ALA as the photosensitising agent in an effort to reduce skin sensitivity and oesophageal strictures. However, additional blood pressure and cardiac

then repeated so that the whole Barrett's segment receives two treatments.

16.3%, P=0.03) and cancer (1.2% vs. 9.3%, P=0.045).

to their skin for up to 4-6 weeks after the treatment.

**8.2.2 Photodynamic therapy** 

oesophagus.

and IMC, particularly in patients not suitable for oesophagectomy.

In some cases following ablative therapy for Barrett's oesophagus, a normal squamous epithelium may re-grow over a portion of Barrett's tissue. Endoscopically this appears normal, but these buried Barrett's glands may retain malignant potential. Endoscopists must be aware of this when surveying patients who have previously undergone ablative endotherapy and for this reason life-long endoscopic surveillance is recommended for these patients, even in the absence of residual Barrett's oesophagus.
