<prompt> Which is most common site of Ca pancreas?HeadBodyTailNeck  <response>: Ans: a Head Ref: Robbins, 7th ed, p. 950Most commonly Ca pancreas arises from head.- Head-60- Body - 15- Tail - 5- Diffusely involves the gland-20Carcinoma of pancreas are usually hard, stellate, grey - white poorly defined masses.Two features are characteristic of pancreatic cancer.- Highly invasive.- It elicits an intense nonneoplastic host reaction composed of fibroblasts, lymphocytes extracellular matrix.tdesmoplastic responseTrousseau sign - Migratory thrombophlebitis due to elaboration of platelet - aggregating factors procoagulants from the tumor or its necrotic products.Common sites- Insulinoma - All over pancreas- Pseudocyst - Body tail- VIPomas - Tail- Glucagonoma - Tail 1 million islets max in tail- Somatostatinoma - HeadMolecular cacrcinogenesisK- ras gene chromosome 12p- Most frequently altered oncogene in Ca pancreas,p 16 chromosome 9p - Most frequently inactivated tumour suppressor gene in pancreatic cancer.SMAD 4 chromosome 18q - Tumour suppressor gene is inactivated in 55 of pancreatic cancers.p53 - chromosome 17p - Inactivation of the p53 tumour suppressor gene is seen in 50 - 70 of pancreatic cancers. 