A new study led by scientists at the University of Southampton has found that inherited variation in a particular gene may be to blame for the lower survival rate of patients diagnosed with early-onset breast cancer.
Breast cancer is the second leading cause of cancer-related death in women, with nearly 450,000 deaths per year from the disease worldwide.
However, women aged 15-39 at diagnosis have a poorer chance of surviving their cancer than older women* (although survival rates for the disease are generally high).
This difference is partly due to the higher incidence of adverse tumour types that occur in younger women, but age is an independent risk factor even after accounting for differences in tumour type and treatment.
The Southampton study - one of the largest ever undertaken into the link between genes and breast cancer survival in women aged 40 or under at diagnosis - looked at which factors, other than the features of the cancer tissue, might contribute to the poorer survival rate in younger women.
Scientists discovered that variations called single nucleotide polymorphisms (SNPs) in a particular gene, ADAMTSL1, increased the risk of disease progression - but only in patients with early onset of the disease.
SNPs describe locations in the genome (a person's entire genetic instructions) where a single nucleotide of the DNA sequence may vary among individuals.
Studies such as this look for a link between this type of genetic variation and survival.
The collaborative study is published in the journal Nature Communications.
Lead author Dr William Tapper said that the findings could eventually be used to improve the accuracy of estimates of disease progression, helping clinicians and patients to choose the most effective treatments.
"This is a significant discovery with exciting implications for the future diagnosis and treatment of early-onset breast cancer patients," said Dr Tapper.
"Our findings increase our understanding of the genes and pathways that are involved in breast cancer prognosis, and may provide new targets for the development of novel therapies.
"In the short to medium-term, this genetic factor may be used to improve prognostic models. In the long-term, when more is known about the mechanism underlying this association and its relationship with treatment response, it may have an influence on approaches to the most effective breast cancer treatments."
Dr Tapper added that additional studies would be needed to fully investigate the findings and their implications.
Source: University of Southampton