Breast tissue, like the gut, has a microbiome, and understanding it could lead to a new understanding of breast cancer, say researchers at the Cleveland Clinic.

The research team has found there are differences in the bacterial composition of healthy women when compared to those with breast cancer. They discovered that healthy breast tissue contains more of the bacterial species Methylobacterium.

Bacteria that live in the body, known as the microbiome, influence many diseases. Most research has been done on the "gut" microbiome, or bacteria in the digestive tract.

Researchers have long suspected that a "microbiome" also exists within breast tissue and plays a role in breast cancer, but it has not yet been characterized. The researchers have taken the first step toward understanding the composition of the bacteria in breast cancer by uncovering distinct microbial differences in healthy and cancerous breast tissue.

"To my knowledge, this is the first study to examine both breast tissue and distant sites of the body for bacterial differences in breast cancer," said co-senior author Dr. Charis Eng. "Our hope is to find a biomarker that would help us diagnose breast cancer quickly and easily."

Eng says the hope is to eventually use microbiomics before breast cancer forms, and then to prevent cancer with probiotics or antibiotics. 

Researchers examined the tissues of 78 patients who underwent mastectomy for invasive carcinoma or elective cosmetic breast surgery. In addition, they examined urine and bacteria in the mouth to determine the bacterial composition of these distant sites in the body.

In addition to the Methylobacterium finding, the study, which was published online in Oncotarge, discovered that cancer patients' urine samples had increased levels of other bacteria, including Staphylococcus and Actinomyces, although it is unclear if they have a role in breast cancer.

"If we can target specific pro-cancer bacteria, we may be able to make the environment less hospitable to cancer and enhance existing treatments," said co-senior author Dr. Stephen Grobymer.

About 12 percent of American women will develop breast cancer during their lifetime. After skin cancer, it's the most common cancer in women.

Approximately 252,710 new cases of breast cancer are expected to be diagnosed in 2017, according to the American Cancer Society, with 81 percent being diagnosed in women aged 50 and older.

Although breast cancer death rates have declined since 1989, over 40,000 American women die from breast cancer each year.