The number of cancer cells in blood samples taken before and after treatment for advanced neuroendocrine tumors could provide a “snapshot” of how well patients are responding to treatment.

By monitoring cancer cells circulating in the blood, doctors may be able to predict treatment success within weeks of starting treatment for this rare cancer type, which most commonly affects the gut or pancreas.

Scientists at the University College London Cancer Institute (UK) analyzed blood samples from 118 patients with advanced neuroendocrine cancers attending the Neuroendocrine Tumor Unit at the Royal Free Hospital (London, UK). They compared the numbers of individual tumor cells present in samples taken before and after treatment.

Patients with circulating tumor cells (CTCs) in the blood at the start of treatment were around eight times more likely to die from their disease, compared to those without CTCs. Following treatment, patients whose CTC levels fell by more than two thirds within five weeks tended to have the best outcomes, while those whose CTC levels rose by more than a third did the worst.

Doctors normally rely on computed tomography (CT) or magnetic resonance imaging (MRI) scans to tell them if a treatment is working, but cutting-edge CTC testing can provide an overall snapshot of the tumor's development, without the need to wait for changes in its size to become visible on scans. Tim Meyer MD, the study leader, said, "By using state-of-the-art technology to count individual tumor cells circulating in the blood stream, we’ve been able to show how a simple blood test could help monitor treatment response and predict how fast the disease will progress."

Joanna Reynolds, PhD, the director of UK’s Cancer Research centers, said, "Advanced cancers often consist of lots of smaller tumors around the body, many of which will be too tiny to be picked up by traditional imaging techniques, making it difficult to judge how well a drug is working. This study highlights a potential way to monitor response in real time across all cancer sites, so doctors know sooner if a treatment isn’t working. Although at an early stage, this is an exciting area of exploration and we look forward to seeing how it progresses." The study was presented on June 4, 2012, at the American Society for Clinical Oncology cancer conference held in Chicago (IL, USA).

Related Links:
University College London Cancer Institute
Royal Free Hospital