25 May 2011
Optical spectroscopy method distinguishes benign pancreatitis and early signs of cancer.
A new optical technique is shown to reduce the mortality of patients affected by pancreatic cancer, writes Matthew Peach. Mary-Ann Mycek, Associate Professor in the Biomedical Engineering department at the University of Michigan, has developed the technique that probes a tumor in the pancreas in vivo for diagnostic applications.
Crucially, the technique can differentiate between three types of pancreatic tissue: “normal” cells; those affected by pancreatitis (non-cancerous); and cells showing early signs of cancer.
Mycek told a packed Biomedical Optics conference,: “If successful this technology could impact on around 30% of pancreatic cancer patients - meaning earlier diagnosis and treatment. Therefore the technique gives potential for curing the condition.”
Pancreatic cancer (Pancreatic Adenocarcinoma) is the fourth leading cause of cancer death in the US with a five-year survival rate of only 5%. As cure and survival rates of many other common cancers have generally improved, pancreatic cancer has stubbornly resisted early detection and therefore treatment that could save more patients.
One of the main reasons for this is the inaccessibility of the pancreas, a gland that produces digestive enzymes, located behind the stomach.
The two main current diagnostic methods, which are unable to reliably detect early stage cancer, are:
1. ERCP – Endoscopic Retrograde Cholangiopancreatography, the problem of which is low sensitivity and specificity i.e. differentiation between pancreatitis (inflammation) and cancer; and
2. EUS-FNA – Endoscopic Ultrasound Fine Needle Aspiration, which can detect 2-3mm sized tumours in the early stages – although inconsistently.
Mycek’s team established that the biophysical differences among pancreatic tissue types affect optical spectra differently. Fluorescence can be used to identify endogenous biomolecular composition; and reflectance for tissue absorption and scattering.
The Michigan team collected spectral data from freshly excised human pancreatic tissue and identified distinct fluorescence and reflectance spectral profiles for the three tissue types of interest: normal; pancreatitis-affected; and adenocarcinoma-affected.
Mycek commented, “We developed quantitative photon-tissue interaction models and tissue classification algorithms and used them to successfully distinguish between these pancreatic tissue types. These studies suggest that multi-modal optical spectroscopy is promising as a potential clinical method to differentiate diseased and normal pancreatic tissues.”
The method of cell identification in vivo is based on an endoscope-ultrasound guided optical “pathfinder probe”, developed by the team. During the EUS-FNA procedure the probe is sent into the patient’s stomach and positioned in the vicinity of the pancreas.
Then the fiber optic probe is inserted through a hollow needle into contact with the suspect tissue. Pulses of light rapidly interrogate the tissue immediately providing guidance for FNA (fine needle aspiration) or providing tissue classification.
Following the team's research and development work, IRB (Institutional Review Board)-approved in vivo human studies are now underway in the United States.