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Lori Elliott-Bartle, (402) 280-2607, [email protected]
CREIGHTON RESEARCHERS SHOW SURVIVAL ADVANTAGE WITH CERTAIN TYPES OF HEREDITARY COLON CANCER
For Immediate Release, Aug. 13, 1998
OMAHA, Neb. -- In a recent issue of the medical journal Cancer, Creighton researchers published an article proving that people who have hereditary nonpolyposis colorectal carcinoma (HNPCC, also known as the Lynch syndrome) have a significantly better survival rate than those who develop sporadic colorectal cancer.
"The estimated death rate for the HNPCC cases, adjusted for [tumor] stage and age differences, was at most two-thirds of the rate" for sporadic cases, says the article.
Genetic biostatistician Patrice Watson, Ph.D., associate professor in Creighton's Department of Preventive Medicine and Public Health, was the study's lead author. She compared tumor stages and survival rates in a retrospective study of HNPCC family members who developed colorectal cancer and people who developed sporadic cases of colorectal cancer.
"I had discussed survival advantage in HNPCC back in the late 1970s and early 1980s, but that was based upon a comparison with a historical cohort," said Henry T. Lynch, M.D., director of Creighton's Hereditary Cancer Institute and a co-author of the study. "Patrice has made the giant leap through developing the data set with careful staging, and comparisons on a matched control cohort. I consider this to be the most definitive paper of its kind dealing with survival advantage in the Lynch syndrome."
HNPCC patients generally develop colorectal cancer at younger ages, about 20 years earlier than in sporadic cases. The disease is characterized by tumors developing in the right side of the colon, which requires full colonscopy to detect. The hereditary nature of the disease follows a classic Mendelian pattern and the genetic mutations that cause the disease, which have been identified, can also lead to cancers in the endometrium, ovary, stomach, small bowel, pancreas and upper urological tract.
In this study, researchers said that heightened awareness and increased surveillance of HNPCC patients did not contribute to the higher survival rates. The article states, "HNPCC cases are, in fact, lower stage at diagnosis than other colorectal cancer cases, but the difference is largely due to having fewer cases with distant metastases, a deficit which persists even after controlling for tumor depth."
In the cases studied in this project, most cases were diagnosed prior to recognition of the hereditary component of the disease. "Furthermore, the HNPCC survival advantage was consistent across stages and significant in the overall stage-stratified analysis," the article says.
Although causes for the difference in survival rates between HNPCC patients and sporadic colorectal cancer patients have not been pinpointed yet, researchers suggest that the effects of genetic mutations and those mutations in combination with environmental factors may be involved.
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