Is There a Risk of Breast Cancer After Benign Breast Lumps?

Benign breast diseases (cysts, fibroadenoma, adenosis, fat necrosis, papilloma, etc.) are associated with an increased risk of developing breast cancer and have been proposed as a risk factor for personalizing breast cancer screening strategies. This risk varies substantially according to the pathological characteristics / type of benign breast lump. According to Spanish researchers, the way benign breast disease is detected may indicate the likelihood of malignancy, emphasizing once again the importance of regular mammography follow-up. The findings of the team led by the Head of Epidemiology at Hospital del Mar Medical Research Institute in Barcelona, Dr. Xavier Castells, were presented at the 12th European Breast Cancer Conference.

Benign breast disease detected the first time a woman undergoes breast screening is classified as "prevalent" benign breast disease, while cases detected in subsequent screenings are classified as "incident" benign breast disease.

Another researcher in the study, Dr. Marta Román, told conference attendees, "Our findings show that women diagnosed with benign breast disease from the second screening onward have a significantly higher breast cancer risk than those with benign breast disease at their first mammogram."

Details of the Study Involving 600 Thousand Women

• Researchers analyzed data from 629,087 women who underwent 2,327,384 mammograms between 1995-2015 and followed them until 2017.
• They found that women diagnosed with benign breast disease were 2.67 times more likely to develop breast cancer than women without this diagnosis. The risk was 1.87 times higher in those with benign breast disease at their first mammogram. In other words, risk increases when benign breast disease appears in subsequent mammograms and becomes more widespread.
• They also classified benign breast diseases according to whether changes such as hyperplasia were present in the ductal cells of breast tissue, as proliferative (rapidly growing) or nonproliferative. In this study, researchers found that women with proliferative benign breast disease had a 3.28-fold increase in breast cancer risk compared with women without breast disease, while those with nonproliferative benign breast disease had a 1.96-fold increase.

Dr. Román stated, “We found the highest breast cancer risk in women with incident (newly appearing) and proliferative benign breast disease. Breast cancer risk was almost 4 times higher than in women without benign breast disease."

To explain the study findings more clearly with an example:

People with benign breast lumps have a higher breast cancer risk than those without; there is no question about that. However, having benign lumps from the outset differs from having them appear later and grow rapidly. If a woman has no benign-looking lumps on her first mammogram but they appear on subsequent mammograms, this indicates rapidly growing formations in the breast and also increases the risk of malignant (cancerous) growth.

Comments on the Findings

The researchers hope their findings will be useful in designing personalized breast cancer screening strategies to improve the effectiveness of screening.

A woman's likelihood of benefiting from mammography depends on her lifetime risk of developing clinically important breast cancer. Considering individual risk factors beyond age should allow women to be stratified into groups with different breast cancer risks. Personalized, risk-based screening that goes beyond the current "one-size-fits-all" recommendation may improve screening effectiveness. Using information from benign breast disease alongside other factors to develop risk-based screening approaches may help predict whether a woman will develop breast cancer within a particular period.

Different screening strategies can be considered for each woman according to her personal breast cancer risk: mammography, ultrasound or magnetic resonance imaging, with screening intervals adjusted to every 6 months, annually or every 2 years.

These findings will help physicians understand the different risks associated with benign breast disease and improve the accuracy of breast cancer risk estimates.

• You may also be interested in: Breast cancer in young girls and benign breast lumps