Health Rounds: Exposure to bacterial toxin may explain earlier age colon cancer rise
Childhood exposure to a bacterial toxin in the colon may be triggering the increase in colorectal cancer cases among younger patients, a new study suggests.
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Once considered a disease of older adults, colorectal cancer is now on the rise among young people in at least 27 countries. Its incidence in adults under 50 has roughly doubled every decade for the past 20 years.
Looking for clues as to why, the researchers analyzed genes of 981 colorectal cancer tumors from patients with varying colorectal cancer risk levels who had early- or late-onset disease in 11 countries.
DNA mutations in colon cells that are known to be caused by a toxin produced by Escherichia coli, called colibactin, were 3.3 times more common in adults who developed colon cancer before age 40 than in those diagnosed after age 70.
The patterns of mutations are thought to arise when children are exposed to colibactin before age 10, researchers reported in Nature, opens new tab.
The mutation patterns were particularly prevalent in countries with a high incidence of early-onset cases.
'If someone acquires one of these... mutations by the time they're 10 years old, they could be decades ahead of schedule for developing colorectal cancer, getting it at age 40 instead of 60,' study leader Ludmil Alexandrov of UC San Diego said in a statement.
'Not every environmental factor or behavior we study leaves a mark on our genome,' said Alexandrov. 'But we've found that colibactin is one of those that can. In this case, its genetic imprint appears to be strongly associated with colorectal cancers in young adults.'
The researchers have found other mutational signatures in colorectal cancers from specific countries, particularly Argentina, Brazil, Colombia, Russia and Thailand.
This suggests that local environmental exposures may also contribute to cancer risk, they said.
'It's possible that different countries have different unknown causes,' study co-author Marcos Diaz-Gay of the Spanish National Cancer Research Center in Madrid said in a statement.
'That could open up the potential for targeted, region-specific prevention strategies.'
DRUG MAY AVERT LIVER TRANSPLANTATION FOR BILE DUCT DISEASE
A recently approved Ipsen (IPN.PA), opens new tab drug has the potential to become the first pharmaceutical alternative to liver transplantation for an autoimmune disease that destroys the bile ducts inside and outside the liver, the company said on Thursday.
The company plans to report the results of its mid-stage trial of Irqirvo in patients with primary sclerosing cholangitis at the European Association for the Study of the Liver, opens new tab meeting in Amsterdam next month.
In a 12-week study, 68 patients with PSC received Irqirvo in daily doses of 80 milligrams or 120 mg, or a placebo.
Patients on Irqirvo had significant improvement in liver enzyme levels, starting as early as four weeks after treatment began, with greater effects seen with the higher dose.
Blood tests also showed liver scarring stabilized to a greater degree in the Irqirvo group, and those on the higher dose of the drug also had significant relief from the itchiness characteristic of the disease.
Rates of adverse events were similar in the three groups.
Irqirvo, already approved for treating a similar condition known as primary biliary cholangitis, is thought to act by stimulating molecules in the body that regulate the processing of fatty acids and by inhibiting bile acid synthesis.
The data are encouraging, study leader Dr. Cynthia Levy of the University of Miami Miller School of Medicine said in a statement.
'PSC is a serious liver disease and currently, liver transplantation is the only treatment that can significantly improve the prognosis,' Levy said, adding that larger trials are needed to further evaluate the potential of Irqirvo in PSC.
SMOKING CESSATION PILL HELPS YOUNG VAPERS QUIT
The quit-smoking drug varenicline, typically used by tobacco smokers, is safe and helpful in teens and young adults addicted to vaping, researchers reported in JAMA, opens new tab.
In their 12-week trial, 261 vapers ages 16 to 25 who wanted to reduce or quit vaping received varenicline, originally sold under the brand name Chantix by Pfizer (PFE.N), opens new tab, or a placebo, in addition to weekly counseling and text message support. All of them had vaped nicotine daily or near daily and did not regularly smoke tobacco.
Continuous abstinence rates in the last month of treatment were 51% with varenicline compared versus 14% with placebo. At six months -- some two months after they stopped treatment -- abstinence rates were still 28% in the drug group vs 7% among those who had received the placebo.
Adverse event rates were similar in the two groups.
'To our knowledge, this is the first pharmacotherapy trial for nicotine vaping cessation in youth,' the researchers wrote.
'Most youth who develop addiction to vaped nicotine have never regularly smoked tobacco and wish to quit vaping," they added, "highlighting the importance of these findings that an available pharmacotherapy is effective and well tolerated for vaping cessation in this population.'
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