A new “simple blood test” recently claimed to be able to predict whether a woman will have breast cancer in the future. The news sounds amazing. But, you may be thinking, it seems too good to be true, and you’d be right to think so. In the study, which you can find in the journal Metabolomics, researchers found that a blood test that examines chemicals and molecules in a woman’s blood, known here as a “metabolic profile,” can tell doctors whether the woman will get breast cancer in the next seven years. Although the method is interesting, the study is still in its early stages and only tracks data from about 800 Danish women. Before anyone can say that the blood test is an accurate and sensitive enough method to reliably identify women at high risk for breast cancer, further research needs to be conducted, including studies on larger, diverse groups of women. And, critically, this work needs to demonstrate that the method does not incorrectly identify women who are not at high risk for breast cancer. So it’s too early to say that doctors can now use the blood test to predict which women will have breast cancer. Moreover, the news agency reported the opposite statement, that there is not enough evidence to prove that the blood test is a “substitute for mammography” and that the test results do not contribute to custom screening or supplement mammography. Importantly, in the published article, the researchers themselves say that they still need to do more work to fully understand the implications of the blood test results. More work needs to be done for other countries, other diets, lifestyles, medications and customs of women. This is not to say that this method of blood testing will not yield results in the future as well. Tumor cells use nutrients to have enough energy to grow, and the changes that occur in this way in tumor cells are a fascinating and growing area of research. Scientists are delving into whether these changes can be used to detect disease early, monitor response to treatment and develop new therapies. But these are still early days. For now, this is an interesting work that may give rise to the development of new assays in the future. Such tests may, one day, help doctors diagnose women who are at high risk of developing breast cancer. But it’s still too early to say that.