Too Early to Declare Victory In the War Against Breast Cancer
The news was good: A drug that is used to prevent bone thinning in older women can also reduce the risk of breast cancer. Rah! Rah! Raloxifene! This drug beat out its cousin tamoxifen, an earlier winner in the breast cancer prevention sweepstakes. And so, with preliminary results in from a large study of post-menopausal women sponsored by the National Cancer Institute, the medical generals declared a victory last month.
Oh really? Perhaps it's a sign of age, but I've grown wary over the years of these medical victories. Raloxifene is being hailed as a preemptive strike against breast cancer, a new weapon to stop insurgent cells before they get started. The same fanfare accompanied the news a few years ago that tamoxifen had reduced the risk of breast cancer compared to a placebo. In the latest study, both raloxifene and tamoxifen reduced the risk, but raloxifene had fewer side effects. Rah! Rah!
But as I think about the nearly 20,000 women in the study, I get uneasy. First of all, the study did not prove that the drug prevented cancer in any specific woman. And how significant were the gains compared to the risk of side effects from the drug?
All the women in the study were healthy, with no symptoms of cancer. Only 2 percent of women in each arm of the study developed breast cancer. (There was no placebo control group. Previous research suggests that about 4 percent would be expected develop breast cancer.)
The vast majority was not ever going to develop breast cancer. Yet they were taking a drug aimed at preventing it -- a drug with side effects, including an increased risk of strokes. How does the individual woman calculate the benefit of raloxifene compared to its risks? Should 9 million post-menopausal women now stampede to their pharmacies for the raloxifene fix in hopes of preventing breast cancer?
To question this victory almost seems unpatriotic. All of us have grown up in the war against breast cancer. Some of us have faced this enemy as patients and survivors. Most of us have lost women we have loved to this disease -- and we have sustained the ones who survived. Breast cancer is more than an illness. It is a metaphor for women's struggle for a long, healthy life against an enemy that is elusive, vicious and often lethal.
This is so even though breast cancer is not the leading killer of women -- heart disease is. Nor is it the leading cancer killer -- lung cancer is. But it is the most common cancer for women and the greatest killer of women under 60. For many of us in this era of longevity, breast cancer is often our first major confrontation with death, directly or indirectly.
That's why we are eager foot soldiers to win the war on cancer. The dark side is that we make big victories out of small advances, which may or may not hold up after the cheering stops.
The National Breast Cancer Coalition held its annual meeting in Washington over the weekend to discuss the latest research and public policy issues. (Disclosure: I was on a panel that discussed media coverage of health.) For the past 15 years, this grassroots organization has evaluated scientific studies and medical practices. And it has often stood out as a critic of the breakthrough psychology that tends to drive the politics of breast cancer.
"We take controversial positions," said Fran Visco, the head of the organization and a breast cancer survivor. "We look beyond the sound bites. We've taken on the research community. . . . That can be difficult for the establishment." The coalition has concerns about this latest "victory."
For starters, the group points out, the results of the Study of Tamoxifen and Raloxifene (STAR) Trial have to be published in a scientific journal before a full analysis of the benefits and risks can be made.
Part of the problem is the difficulty in determining a woman's chances of developing breast cancer. All of the women in the study were deemed to be at increased risk. But the scale used to measure increased risk based on age and personal and family history casts such a wide net that millions of women may be considered candidates for preventive treatment -- even though most of them will not get breast cancer. As yet, there are no definitive techniques to identify who will and who won't.
Another part of the problem is in determining long-term benefit.
The latest study, which lasted only five years, doesn't answer whether these drugs "will reduce a woman's overall risk of developing or dying from breast cancer, or extend a woman's life," according to the coalition's official response to the new trial. The study doesn't clarify when or how long asymptomatic women should take such preventive drugs. And it doesn't address "how many of these women will ultimately develop adverse effects from taking these drugs over the long term, or the mortality rates associated with these adverse effects."
This latest study is not a victory. It's promising research. It plays on our medical patriotism to win the war on breast cancer. But sometimes it's more patriotic to resist the clamor for victory and settle for more cautious bulletins. ·