What Does the Network Think? Will a New Test for Women with Breast Cancer Help Avoid Unnecessary Chemotherapy?

by Cindy Pearson
Breast cancer patients and others interested in the disease may have noticed press reports last fall, announcing that a new test might be able to help patients find out whether or not they need chemotherapy. This announcement caught NWHN’s eye, as the question of whether or not women with early breast cancer need chemotherapy is an important one.
Currently, most women whose breast cancer is found early are strongly encouraged to consider having four to six months of chemotherapy. Randomized trials have shown that this treatment improves women’s chances of survival—but the benefit comes at the cost of short-term misery, and possible long-term ill effects. Given chemotherapy’s downside, it is important to use it only when it is most likely to help. Randomized trials have been useful in identifying which sub-groups of women seem to benefit the most from chemotherapy, such as women under 50 or women with rapidly growing tumors. It is much harder to know whether an individual woman is likely to benefit from chemotherapy or not.
In Europe, women with early breast cancer typically do not use chemotherapy, but the treatment is very common in the U.S., which tends to have a more aggressive approach to treating cancer. Long-term survival after treatment for early breast cancer ranges from 70 to over 90 percent; chemotherapy improves these odds by anywhere from 2 to 20 percent. These statistics mean that, overall, most women with early breast cancer who are given chemotherapy didn’t need it. But the unanswerable question, at least so far, is which women don’t need chemotherapy and which will benefit from it. Current tests used to predict the recurrence of breast cancer (such as flow cytometry and hormone receptor status) help determine which women will benefit from chemo to some extent, but still leave patients and doctors with much uncertainty. A better test could be very useful, reassuring many women that there is a low risk that their tumors will recur and that they can safely be treated without chemo.
Several research groups and companies are actively investigating different approaches to predicting breast cancer recurrence through various types of tests. The results of one of these tests, called ‘Oncotype DX’, were presented at the annual meeting of breast cancer specialists in 2004, generating press coverage and lots of questions from patients. Oncotype DX tests for certain genes within an individual tumor and uses the results to predict the likelihood of breast cancer recurrence. Based on retrospective studies of women whose cancer was treated many years ago, the Oncotype DX test is useful. A study to this effect was published in a leading medical journal after being reviewed by scientists without connections to the company that owns Oncotype DX. Based on this work, the company has made the test available commercially. (Due to the way in which the test is conducted, FDA approval isn’t necessary.) The positive results found in the retrospective study have not, however, been replicated in a prospective study--which is typically required to establish that a test can predict the future course of a disease. The National Cancer Institute is planning to conduct a prospective study, and the Network encourages patients to consider volunteering for this research. The bottom line is that the problem of over-treating early breast cancer is real – and we’re going to have to wait a while longer to find out if benefit from new tests is equally real.
Cindy Pearson is the Executive Director of the NWHN.