New Blood Test Predicts Breast Cancer Treatment Success Before Therapy

Breast cancer patients may soon benefit from a groundbreaking blood test that can predict how well they will respond to treatment even before therapy begins, offering new hope for improved survival and quality of life. Researchers have developed a liquid biopsy that analyses tiny fragments of cancer DNA circulating in the blood, enabling doctors to identify which treatments are most likely to work for individual patients. Published in the journal Clinical Cancer, the test could help clinicians avoid ineffective therapies, switch to better options sooner, and personalise treatment plans at a much earlier stage. Breast cancer is a disease where cells in the breast grow abnormally and form a harmful lump. It usually starts in the milk ducts or milk-producing glands and can spread to other parts of the body if not treated early. It happens when breast cells change and begin to grow out of control. These changes may be inherited or develop over time. Risk factors include getting older, having a family history of breast cancer, hormone changes, being overweight, drinking alcohol, and lack of exercise. Sometimes, it occurs without a clear cause. According to the World Health Organisation (WHO), breast cancer is the most common cancer worldwide and the most common cancer in Kenya, especially among women The study, led by scientists at the Institute of Cancer Research, focused on patients with advanced breast cancer. Using blood samples, researchers measured levels of circulating tumour DNA genetic material released into the bloodstream by cancer cells—both at the start of treatment and again four weeks later. They then compared ctDNA levels with patient outcomes, including how well tumours responded to treatment and how long the cancer remained under control. Research has revealed a strong link between low ctDNA levels and better treatment outcomes. Patients with low or undetectable ctDNA at the start of therapy, or after just one treatment cycle, were significantly more likely to respond well to treatment. Patients were divided into two groups based on cancer type and genetic mutations: Group one included patients with mutations such as ESR1, HER2, AKT1, AKT, or PTEN, who received targeted therapies matched to their specific mutations. Group two consisted of patients with triple-negative breast cancer, an aggressive form of the disease with no targetable mutation. These patients received a combination of the PARP inhibitor olaparib and the ATR inhibitor ceralasertib. Among patients with triple-negative breast cancer, those with low ctDNA levels before treatment experienced longer progression-free survival—an average of 10.2 months, compared with 4.4 months for patients with higher ctDNA levels. Treatment response was also significantly better: 40 per cent of patients with low ctDNA saw their tumours shrink or disappear, compared with just 9.7 per cent among those with higher levels. In patients receiving targeted therapies, a similar—though weaker—relationship was observed before treatment began. However, the results after four weeks were striking. Patients whose ctDNA became undetectable went on to have much better outcomes, with their cancer controlled for 10.6 months, compared with 3.5 months for those with detectable ctDNA. In the triple negative group, patients whose ctDNA disappeared after four weeks had their cancer kept at bay for 12 months, compared with 4.3 months for those whose ctDNA remained detectable. Treatment response in this group rose dramatically to 85.7 per cent, versus 11.4 per cent among patients with detectable ctDNA. Dr Iseult Browne, clinical research fellow at ICR and first author of the study, said the test could transform how breast cancer is treated. “Knowing whether a treatment is likely to work at the earliest stage—either before treatment starts or after just four weeks—means we can avoid giving patients drugs that won’t help them,” she said. “Instead, we can offer alternative therapies or enrol patients into clinical trials before their cancer has a chance to progress.” Researchers note that the liquid biopsy has the potential to make treatment decisions faster, more personalised, and ultimately more effective Further trials are now underway to determine whether adapting treatment based on early ctDNA results can directly improve long-term patient outcomes—bringing hope that a simple blood test could soon help many more patients live longer, healthier lives with breast cancer. The breakthrough comes at a critical time. Breast cancer is the most common cancer worldwide, with an estimated 2.3 million new cases each year. In Kenya, it is the leading cancer among women, accounting for more than 6,000 new cases annually. Breast cancer remains a serious health challenge both globally and in Kenya. According to the World Health Organisation, breast cancer is the most common cancer in women around the world, with an estimated 2.3 million new cases and about 670,000 deaths in 2022. The WHO also projects that, if current trends continue, global breast cancer cases could rise by 38 per cent and deaths by 68 per cent by 2050, with low- and middle-income countries being disproportionately affected. In Kenya, breast cancer is the leading cancer among women and one of the most diagnosed types of cancer overall. National statistics show that Kenya records around 6,700 new breast cancer cases and about 3,100 deaths each year, making it the most common cancer in the country.) Cancer in Kenya overall accounts for tens of thousands of new cases annually, and breast cancer contributes a large share of this burden, often being detected at advanced stages when outcomes are poorer. Treatment for breast cancer varies depending on how early it is detected and the specific characteristics of the tumour. Common treatments include surgery to remove the tumour, chemotherapy to kill cancer cells, radiation therapy, hormone therapy for cancers driven by hormones, and targeted treatments that act on specific cancer cell features. In many cases, doctors use a combination of these treatments to improve the chances of success. Early detection through screening and awareness of symptoms continues to be crucial, as it can significantly improve survival and quality of life for those diagnosed.