Predicting Breast Cancer Outcome
A Protein May Be the Most Accurate Guide to Breast Cancer Survival
Nov. 13, 2002 -- The most accurate way to predict the outcome of breast cancer in an individual may be a simple lab test that measures a tumor's levels of a particular protein.
With this test, say researchers, thousands of women diagnosed with breast cancer may be able to avoid unnecessary chemotherapy treatments, while others can be identified for more aggressive treatment even when other tests indicate the cancer hasn't spread.
It all depends to the patient's levels of cyclin E, a protein that helps cells to proliferate, say researchers. High levels of cyclin E in breast cancer tumors correlate to a poor outcome, while low levels are associated with the best rates of survival, according to a study in the Nov. 14 issue of TheNew England Journal of Medicine.
In the study, the researchers analyzed tumors from almost 400 breast cancer patients and compared the levels of cyclin E to known survival factors.
They found that higher levels of cyclin E were associated with a higher death rate during an average five-year follow-up period.
Among 114 patients with early-stage breast cancer, all of the patients that had high levels of the protein (12 patients) died within five years. None of the 102 patients with low levels of cyclin E died of breast cancer during that period.
This same association was seen in more advanced breast cancer patients as well. But for the most advanced cases -- stage IV breast cancer -- cyclin E had no effect on survival.
For all breast cancer patients, survival over time was diminished 13-fold in patients with high levels of cyclin E.
"This is significant because we have now identified a detection method using a biomarker that can accurately identify whether a tumor will have a good prognosis or a poor prognosis," says lead researcher Khandan Keyomarsi, PhD, of the University of Texas M.D. Anderson Cancer Center in Houston. "And thus, we can better determine the best treatment for patients.
"In patients who have low levels of cyclin E, we can predict a good prognosis and they may not need to undergo chemotherapy," she tells WebMD. "It's also important because in about one-third of cases where tests indicate negative (cancer-free) lymph nodes, the cancer recurs. So if these women have higher levels of cyclin E, they might warrant more aggressive treatment."
Although experts don't know what factors influence cyclin E levels or what you could do to lower them, they do know that this protein seems to be a factor in the development of malignancies.
In normal cell growth, cyclin E levels vary depending on the stage of development. But in tumor cells, cyclin E levels remain high and also appear in a more active form. "Basically, the same type of cyclin present in normal cells for short time is present continuously in tumor cells," says Keyomarsi.
A study in the February 1997 issue of Nature Medicine showed that high levels of cyclin E, along with low levels of another cell protein, were associated with a ninefold increased risk of death in breast cancer patients.
The researchers conclude that if cyclin E's role in breast cancer is verified, cyclin E measurements may be used to obtain survival information and allow for more appropriate treatment for individuals.