Acid Reflux -> Oesophagitis -> Barrett's Oesophagus -> Oesophageal cancer
Acid refluxing into the oesophagus may wash aside the mucous lining and attack the squamous cells beneath - in the same way as pouring acid on your hand would burn and scar. This may be felt as heartburn and continued erosion can result in oesophagitis.
If bile refluxes onto the inflamed area, it could permit the acid to start digesting the exposed lining in the same way as it would break down ingested animal products. As a protection, the squamous cells can be replaced by columnar cells.
An analogy is to think of squamous cells as dominoes lying on a table. Columnar cells are like dominoes standing
This is the condition known as Barrett's Oesophagus and it is a permanent change. Sometimes Barrett's appears to go away but if it's not seen, it may be hidden in the corrugations of the epithelium or a second mucosal layer may have grown over it. The burning sensations may reduce or disappear adding to the illusion that the Barrett's has gone but Barrett's itself is asymptomatic and the cells being less sensitive are protecting against the pain.
However, these cells are unregulated and in a small minority of cases can mutate. In our analogy, it's like some of the dominoes toppling. This is called Low Grade Dysplasia (LGD).
If a large mass of these dominoes topples into a disorganised heap, it's known as High Grade Dysplasia (HGD).
Further mutations may now occur which can cause a proliferation of mutated cells which is Oesophageal Adenocarcinoma - that's cancer!
The different stages of Barrett's Oesophagus are:
The phrase "Uncertain for Dysplasia" is often used if there is uncertainty whether it's NDBO or LGD.
It must be stressed that the chances of progression of Barrett's Oesophagus to Oesophageal cancer are very low and it is treatable.
Image courtesy of Action Against Heartburn
The chart above shows the risk of developing cancer in any one year is higher if there is high grade dysplasia. People aged 30 years with newly-developed Barrett's Oesophagus may have a risk of 11-25% of developing adenocarcinoma before they reach the age of 80 but there are may variables to take into account.
Britain tops the world for incidence of oesophageal cancer where it is the fifth greatest cancer killer claiming the life of one person an hour on average in the UK. [c-i]
If it is going to occur, the progression is usually slow initially but by the time cancerous cells develop, it's frequently too late to treat with life expectancy measured in weeks rather than years.
There may be 1 million people in UK with Barrett's* but fewer than 10% know it. If the others can be identified, it may be possible to prevent this large number of deaths.
The size and extent of an observed area of Barrett's may be described using the Prague criteria using the letters c for circumferential ring and m for maximum length of any tongues. Thus c2m3 would mean a ring of Barrett's 2 cm wide with protrusions to a maximum of 3 cm.
* There are various estimates of the number of people in UK with Barrett's. The commonly quoted figure presently is about 750,000 but this may be an underestimate.
The Ryan Hill Research Association in USA reported a number of years ago that autopsy studies "have reported that up to 1 in 80 to 1 in 60 persons may have Barrett's esophagus". With a UK population of 64 million, using those statistics would indicate about 1 million with Barrett's in UK. Deaths to oesophageal cancer in USA account for 0.005% of the population whereas in UK, deaths to oesophageal cancer account for 0.012% - two and a half times higher. Could this perhaps indicate the possibility of 2.5 million with Barrett's in UK?