Colorectal and endometrial cancers are the most frequent malignancies in people with Lynch syndrome, with respective cumulative risks of 60%–80% and 30%–50%.
The good news from a Dutch study is that a comprehensive screening program may cut the incidence of colorectal cancer (CRC) in this high-risk population by 70% (Gastroenterology 2006;130:665–71).
Cancer mortality in a large cohort of Lynch syndrome patients was compared with that in the general Dutch population by computation of the standard mortality ratio (SMR)—which is observed deaths/expected deaths—and absolute excess risk of death.
Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer, is a rare disorder that usually causes the development of colorectal, endometrial, and other forms of cancer.
The study evaluated the effectiveness of a large-scale cancer surveillance program. More than 2,700 individuals in 140 families fulfilled the selection criteria for being mutation carriers, putative carriers, or first-degree relatives of carriers.
The SMR for CRC decreased significantly between 1960 and 2004, from 32 to 10. In contrast, there was no significant change in the SMRs for all other cancers, including endometrial cancer (EC).
Among those who did not have a surveillance colonoscopy (1,073 patients), the SMR was 23.9, versus 6.5 for the group that had the test. The death rate for all cancers—barring CRC—was higher among women than men.
“The most frequent causes of death in the total cohort were CRC, EC, brain tumor, lung cancer, and cancer of the stomach,” the authors said. Although the CRC death rate decreased after initiation of the registry and screening program, the SMR increased significantly for cancers of the small bowel, brain, kidney, ovaries, pancreas, and stomach.
“A striking finding in the present study,” the authors observed, “was that there was no difference in EC mortality between relatives from hMLH1/hMSH2 and hMSH6 (germ line mutation) families despite the reported higher risk of EC in MSH6 mutation carriers compared with the risk in MLH1 and MSH2 mutation carriers” (Gastroenterology 2004;127:17–25).
“Although the observed decrease in CRC mortality since the start of large-scale surveillance programs is encouraging, the mortality because of this cancer is still relatively high,” and thus long-term studies are needed, they wrote.