What All of Us Shows About Cholesterol and Breast Cancer Risk

In Short

High ​cholesterol can raise someone’s risk of having a heart attack or stroke, but does it affect their risk for other conditions, such as ​breast cancer? Previous studies haven’t agreed. So researchers turned to All of Us data to clear up the confusion. 

The data in All of Us allowed them to study individual cholesterol measures and other factors. This helped them get a more complete picture of the link between cholesterol levels and breast cancer risk. They learned that having too much of one type of cholesterol is related to a higher risk of breast cancer. Age plays a role in whether another type of cholesterol affects breast cancer risk. These results were published in the journal Cancer Informatics. 

The Good and the Bad

Cholesterol is a fat-like substance in your blood. There are two types: 

• LDL: Known as “bad” cholesterol, because high levels of it are bad for our hearts. 

• HDL: Known as “good” cholesterol, because high levels of it are good for our hearts. 

LDL and HDL are often measured together as total cholesterol levels, but they can be counted and studied by themselves. In addition, researchers often study triglyceride levels alongside cholesterol. High levels of these fats in our blood can be harmful to our hearts. 

LDL, HDL, total cholesterol, and triglycerides may have their own effects on breast cancer risk. Other factors, such as age, may also play a role. 

Links to Breast Cancer Risk

In this study, researchers looked at All of Us data to consider all of these factors. They studied data from electronic health records (EHRs) and physical measurements shared by more than 6,300 female participants with breast cancer. 

• In general, high levels of bad cholesterol and high total cholesterol levels were related to a higher risk of breast cancer.  

• The effect of good cholesterol levels on breast cancer risk depended on age. Participants age 56 and older with low levels of good cholesterol had a higher risk of breast cancer. But in participants younger than that, good cholesterol levels did not affect breast cancer risk. 

• Triglyceride levels were not linked to breast cancer risk. 

Clearing Up Confusion

Researchers were able to see these relationships in participants who had not taken cholesterol medicines called ​statins. Statins help lower bad cholesterol. 

But the relationships were not as clear in participants who had taken statins. That could help explain why past studies have had mixed results. The large number of participants in All of Us who have shared their EHR data made it possible for researchers to separate the two groups to uncover the effects of the medicine. 

This research helps clear up some of the confusion around cholesterol levels and breast cancer risk. But there are limitations. The study included only females because there were too few people of other genders with breast cancer in the dataset to be able to get accurate answers. We do not know whether the results of this study apply to people of all genders. 

This study could not look at all the factors that could influence cholesterol levels or breast cancer development. It started with age and statin use. But what if other medicines, or someone’s job, or their environment play a role? Now that we know a little more, future studies can look into other factors. 

This work and future studies are possible thanks to the size and diversity of the All of Us dataset. In time, this research could help health care providers better identify people who are more likely to develop breast cancer. Then they may be able to take steps to prevent breast cancer, get screened earlier, and get treatment sooner.