[From CNN.com]
The chances of surviving ovarian cancer appear to vary dramatically depending on the levels of two tumor proteins, suggesting that this type of cancer may have a more nuanced outlook than the grim statistics indicate.
Women who had ovarian tumors with high levels of the two proteins survived for a median of 11 years or more, while those with lower levels survived for a median of about 2.6 years, according to a study published Thursday in the New England Journal of Medicine.
The proteins, known as Dicer and Drosha, could help guide treatment or lead to new types of therapy. They are key players in RNA interference (RNAi), a naturally occurring system that turns genes on and off. The study is the largest to link RNAi with cancer survival rates, and the researchers also found that high Dicer levels are linked to survival in breast and lung cancer.
About 22,430 new cases of ovarian cancer were diagnosed in the United States in 2007, according to the American Cancer Society. Ovarian cancer is often called the “silent killer” because it can be difficult to catch early. Health.com: Should I get tested for the breast and ovarian cancer genes?
In the new study, Anil K. Sood, M.D., of the University of Texas M.D. Anderson Cancer Center, in Houston, and colleagues analyzed tissue from 111 women with advanced epithelial ovarian cancer, specifically looking for Dicer and Drosha. They found 60 percent of the cancers had low levels of Dicer, 51 percent had low levels of Drosha, and 39 percent had low levels of each.
These two proteins are responsible for cutting and shaping tiny snippets of genetic material known as microRNAs, or miRNA. In the past decade, scientists have discovered that these naturally occurring snippets are important for turning genes on and off, controlling cell growth, and determining whether cells live or die. The entire process is known as RNAi, and when the system is damaged it can lead to disease. In fact, RNAi is abnormal in just about every cancer that researchers have examined.
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