Healthcare Professionals

Screening and Early Detection

There has been an immense interest in early detection of pancreatic cancers because 85% of pancreatic cancers are detected late at an incurable stage. The screening and detection techniques that are used are computed tomography (CT) scan, magnetic resonance imaging (MRI)/ magnetic resonance cholangiopancreatography (MRCP), and endoscopic ultrasonography (EUS). CT scanning technology has improved in recent years. However even then, conventional imaging like abdominal ultrasound, CT scanning and MRI are not sufficiently sensitive for very small early pancreatic cancers to be useful as routine screening tools. With EUS, the accuracy of diagnosis is close to 100%. EUS can easily differentiate between solid and cystic lesions. Fine needle aspiration under EUS can detect minute lesions of 2 to 5 mm. Serum CA 19-9, is a widely used tumor marker especially in patients with pancreatic cancer. However it has variable sensitivity and specificity.³ Recent approaches to screen high-risk individuals involves EUS of the pancreas, multidetector CT (MDCT) with three-dimensional reconstruction and serum CA 19-9 measurements as the initial screening tests. These are followed by ERCP, EUS-FNA and other investigations, if abnormalities are found on EUS or CT, or both. However, it must be noted that screening of asymptomatic individuals in the normal population is not routinely practiced.

• Biomarkers for early detection

Biomarkers are of three types: DNA, RNA, and proteins. DNA methylation is altered and mitochondrial mutations occur during carcinogenesis and these can be detected by using polymerase chain reaction. Pancreatic juice has a high concentration of DNA and can be an optimal specimen for detection of markers of pancreatic cancer. It can be collected during routine upper GI endoscopy. The DNA methylation patterns are tissue specific and therefore it is necessary to collect the pancreatic juice directly from the pancreatic duct. Detection of pancreatic cancer messenger RNA can also be done. The RNA -based marker that has been investigated to date is hTERT. About ninety percent of cancers express the telomerase hTERT subunit, while 90% of patients with pancreatic cancer have detectable telomerase activity in their pancreatic juice.⁴

The detection of telomerase enzymatic activity or the hTERT subunit is helpful in differentiating pancreatic cancer from benign pancreatic disease. Protein based markers can also be used to detect pancreatic cancer. A technique known as SELDI (surface-enhanced laser desorption ionization mass spectrometry) has helped in analyzing pancreatic juice. It was found that there are elevated levels of hepatocarcinoma-intestine-pancreas/ pancreatitis-associated protein I (HIP/PAP) in patients with pancreatic cancer as compared to patients with other pancreatic diseases. SELDI and other protein profiling techniques are being explored as diagnostic tools in a variety of cancer types. Till date, no specific biomarker can be recommended on a routine for early detection of pancreatic cancer.