Skip to 0 minutes and 15 secondsIn this video, we'll talk about cancer pathology in real patients. We'll talk more about cancer spread. We'll describe how we sample and look at tumours, including tumour grading and staging. Extra tests, including molecular pathology, can help. Cancers spread through local invasion, so-called vascular spread, and then distant metastases. These are parts of the hallmarks of cancer. Local invasion takes place at the primary site where the cancer started. The cancer spreads locally by direct invasion and tissue destruction. Looking down in the microscope, we can see invasion because tumour has crossed normal boundaries. So the tissue architecture is abnormal. For example, in the bowel, adenocarcinoma invades from inner lining through the bowel wall, out into adjacent fat.
Skip to 1 minute and 13 secondsVascular spread is when cancers invade and travel in small vessels, either lymphatics or veins. Lymphatic channels are thin-walled vessels carrying tissue fluid. Lymphatic spread carries tumour to draining lymph nodes nearby. This happens especially with carcinomas and melanomas. For example, in breast cancer, lymphatics spread takes tumour first to the lymph nodes in the armpit, or axilla. Venous spread is when cancers invade and travel in small blood vessels. That is, veins. Venous spread carries tumour to other organs as metastases. This is the main way by which sarcomas spread. But it happens with carcinomas and other cancers, too. Carcinomas can also spread across the abdominal cavity, especially from the ovary and stomach.
Skip to 2 minutes and 11 secondsMetastases are where the tumour has spread to other organs away from the primary site and grown there. Metastases are also called secondary tumours. At the moment, metastases are harder to treat than primary tumours. And it is often the effect of the metastases which cause death in cancer patients. So metastases are important. metastases are particularly common in certain organs, liver, lung, bone, and brain. In fact in the liver, these are the most common tumour. We don't completely understand why metastases grow especially in certain organs. Part of the reason is simply that the veins from primary cancers often drain blood mainly to certain organs. So blood from the colon drains first to the liver. But this isn't the whole story.
Skip to 3 minutes and 6 secondsCancers carry specific proteins on their surface which may help them grow in some organs and not others. This is called the seed and soil hypothesis. And is a big area for research. It is important to know that metastatic tumours have the properties of their tissue of origin not of the site of spread. Metastases look like and respond to treatment like tumours from their site of origin. So colorectal carcinoma, which has spread to the liver, is given colorectal treatment, not hepatocellular carcinoma treatment.
Pathology in the patient: part one
Part one of two. Dr Karin Oien describes how cancers spread or metastasize.
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