Research from Radboud university medical center shows that many of the tumors in patients with Lynch syndrome have microsatellite instability (MSI-H) and mismatch repair deficiency (dMMR). And that makes them susceptible to immunotherapy.
People with Lynch syndrome have an increased risk of colorectal and uterine cancer, but other cancers are also more common. The study was conducted in a group of over 1,700 people with Lynch syndrome. Of these, more than a third developed colorectal or uterine cancer. About 15% developed another form of cancer. Many of these types have previously been associated with Lynch syndrome, such as cancer of the small intestine, stomach and ureter; the so-called Lynch spectrum tumors.
The researchers found specific DNA abnormalities in virtually all Lynch spectrum tumours. Nearly 40% of tumors outside the Lynch spectrum also had these abnormalities. That is remarkably much. In cancer patients without Lynch syndrome, these abnormalities are found in less than 1% of tumors.
In people with Lynch syndrome who develop cancer outside the colon or uterus, it is desirable to examine the tumor for MSI-H and dMMR, the researchers said. If these abnormalities are found, there is a good chance that immunotherapy will be effective.
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