BMJ  2005;330:E344 (16 April), doi:10.1136/bmj.330.7496.E344

BMJ USA: Editor's choice

Prevention, early detection, or treatment?

According to the American Cancer Society, the death rate from breast cancer for women has decreased about 2% annually since 1990. Why are fewer American women dying of breast cancer? Possibilities include changes in the biological behavior of breast cancer (unlikely), decreased incidence rate (preventing breast cancer from occurring), improved early detection (finding curable cancers), or better treatment (using new therapies that prolong life). But which one?

With increased mammographic screening, it is no surprise to find that the incidence of diagnosed breast cancer has actually gone up almost 4% per year since 1990. The hope, of course, is that many of the detected cancers will be curable, or that treating them will result in longer survival times. Studies such as the one by Anne Helene Olsen and colleagues (abstract, p 116) have consistently shown about a 25% decrease in breast cancer mortality attributable to mammography.

Advances in breast cancer treatment make a difference as well. Gianni Bonadonna et al (abstract, p 117) extend the follow-up of patients who received adjuvant chemotherapy from 15 to 30 years, finding that this therapy confers long-lasting benefits for women with operable breast cancer.

In an accompanying editorial (p 102), Alison Jones notes that it is hard to disentangle the relative contributions of screening and treatment in improving breast cancer survival, because both interventions are happening at the same time. Screening delivers more women with early stage (and better prognosis) breast cancer to their doctors for treatment. And adjuvant chemotherapy presumably benefits both women who have been screened as well as those who present with signs or symptoms.

As Jones also points out, what's missing is primary prevention of breast cancer. While it is all well and good to find cancers early and treat them appropriately, we have had precious little success in preventing breast cancer in the first place. What advice can we give to our patients? Minimize exposure to hormone replacement therapy and ionizing radiation, use alcohol with moderation, and avoid obesity. Have your babies early, eat a low-fat diet, and exercise regularly. Maybe consider using selective estrogen receptor modulators like tamoxifen if you are at high risk.

It's a pretty unsatisfactory package. To reduce breast cancer incidence we have neither a pharmaceutical magic bullet like immunizations for infectious diseases nor an effective behavioral change like smoking cessation for lung cancer. Seems like a good place for more attention and resources.

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