Mystery trigger caused cancer surge
Experts admit they have no idea what lies behind the global epidemic of oesophageal adenocarcinoma, which affects the gullet or food pipe.
Known risk factors such as smoking, obesity, and acid reflux cannot account for the rise on their own.
Oesophageal cancer is one of the most deadly cancers, with only around 12% of patients surviving five years or more.
A new study shows a dramatic incidence pattern that first emerged in England and Scotland in the 1960s, with rate increases of up to 5% a year.
The US experienced a similar trend beginning about a decade later. Similar surges were seen in five other countries, including Sweden, where rates began to rise sharply in the early 1990s.
The speed of the increase varied in different locations, ranging between about 3% and 8% a year. Hawaii experienced the fastest annual rise of 8.1%.
Writing in the journal Gut, the researchers describe a “consistent dramatic increase in incidence” was still continuing by 2009. They said the implications were “potentially alarming”.
“A decisive exposure may have been widely introduced within a short time span in the respective populations; however, at points in time that differ by up to 30 years between populations,” said the scientists.
“Although the induction and latency time can only be conjectured, we speculate that the exposure might have been first introduced in the early 1950s (in the UK) and about 10 years later it was spread to certain — but not all — regions of the North American continent.”
After another 10 years, exposure to the trigger occurred in Denmark, Finland, and possibly France. Sweden and Norway were the last countries to be affected in around 1980.
The researchers, who analysed 16 population-based cancer registries, found men were consistently between three and nine times more likely to develop the disease than women. However, the increases in incidence affected both genders equally.
