Around 10,000 women in England are diagnosed with advanced breast cancer every year, new analysis shows.
Data on the number of women with the disease that has spread to other parts of the body, also known as metastatic cancer, is usually counted by the number diagnosed when their cancer is already at a late stage.
But thousands of women will go on to develop the disease after initially being diagnosed with an earlier stage cancer. This gap in the data limits understanding about the volume of women living with advanced disease and may mean their needs can't be properly met, experts say.
Estimates suggest true figure is higher
Around 2,200 a year are newly diagnosed with breast cancer at Stage 4. But the new estimates from Macmillan Cancer Support and NHS England's National Disease Registration Service suggest the true figure is much higher. Experts say this means women are "invisible in reporting," leading to a real risk health leaders can't accommodate their needs.
Researchers looked at cancer data from 2022 in England. Their analysis, presented at the European Society of Medical Oncology conference in Madrid, also estimates the average age women are diagnosed with or develop metastatic breast cancer is just 61. Over half - 52% - will live with metastatic breast cancer for two years or more, the authors told the conference.
Charities call for better data
Claire Taylor, chief nursing officer at Macmillan Cancer Support, said: "The new figures are another wake-up call for metastatic breast cancer."
"Behind these numbers are tens of thousands of women living with incurable cancer, which we know can impact every part of your life - not just your physical and mental health, but your job, finances, relationships with friends and family.
"The fact that these estimates are much higher than the number of women actually being diagnosed at stage 4 alone raises serious concerns that many people living with metastatic breast cancer are effectively invisible in reporting.
"When people are unseen in the data, there is a real risk that their needs are not fully recognised in service planning, research and policy development."
"For too long, gaps in the available data have limited our understanding of the true number of people affected by metastatic breast cancer and the challenges they face." She added: "By bringing together linked NHS data and innovative analysis, we are helping to close those gaps.
"Better data is essential to ensuring that services are planned around the reality of patients' experiences, helping us identify unmet need, reduce unwarranted variation in care, and ensure everyone living with metastatic breast cancer can access the support and treatment they need, wherever they live."
Claire Rowney, chief executive at Breast Cancer Now, added: "We welcome this new study which provides valuable insight into the number of people living with incurable metastatic breast cancer in England who, for decades, have felt that they don't count and that their needs remain hidden with no accurate national data available.
"These findings are a further reminder of the urgent need for accurate data on metastatic breast cancer to be captured and published. Having this data is fundamental for ensuring the right treatment, care and support is provided for people with metastatic breast cancer. Without it their needs can't be properly planned for and resourced by the Government and NHS."
NHS England was approached for comment.
