Scientists have discovered a protein which drives aggressive breast cancer.
Researchers at Cardiff University are hoping new and improved therapies could now be developed for treating the protein.
Their study looked at an aggressive type of breast cancer called triple negative, which is resistant to hormone therapy and occurs in around 15% of cases.
They found that a protein called LYN was affected by aggressive forms of breast cancer and by treating the protein the cancer was altered.
Professor Matt Smalley, from the university's European Cancer Stem Cell Research Institute, said: "There are 150 new cases of breast cancer diagnosed in the UK every day.
"To achieve better outcomes for people facing this disease, we need to better understand how it develops so we can improve therapies.
"We wanted to understand what drives an aggressive type of breast cancer called triple negative, which is resistant to hormone therapy and occurs in around 15% of breast cancer cases.
"We looked at a protein called LYN, which is involved in keeping cells alive and allowing them to divide and found that it was no longer properly controlled in aggressive breast cancer cells and could drive the cancer cell growth, spread and invasion."
The team also found that in a subset of triple negative breast cancer cells associated with the BRCA1 gene mutation, LYN could be switched on and increase cancer cell survival directly as a result of the loss of BRCA1.
BRCA1 is a gene responsible for producing tumor suppressors in the body.
These suppressors are vital in ensuring the genetic material within a cell develops normally.
When the BRCA1 gene is mutated or altered, the body producers faulty suppressors or lacks them altogether, which means damaged DNA is not repaired. This could lead to cells growing and dividing at an abnormal rate, resulting in cancer.
Scientists found that interfering with LYN protein's function under experimental conditions killed BRCA1-mutant cells.
Prof Smalley added: "Now that we understand the role LYN has in aggressive forms of cancer, we can start to think about developing targeted therapies.
"In the future, we could potentially identify patients that have increased levels of LYN or a BRCA1 gene mutation and design their breast cancer therapy to suit their type of cancer.
"We could target LYN to improve therapy options for aggressive breast cancer."
There are around 54,900 new breast cancer cases in the UK every year, that's around 150 every day, according to Cancer Research UK.