Are there any differences when a surgeon takes tissue from secondary place (for example from metastasis) rather then from primary place (from an organ where cancer is) for morphological research?
I would disagree a bit with the previous answer. There are absolutely differences between the metastasis and the primary tumor. One result of this is that people very rarely die of primary tumors, but rather from the metastases of those tumors. The primary tumors will be quite heterogeneous and contain largely cells that have not undergone steps necessary for migration like epithelial to mesenchymal transition. After cells have metastasized they will be separate from the original primary tumor, and contain unique genomes. Because this is the more 'progressed' group of cancer cells, these are often the cells that need to be targeted. So, determination of the proper treatment strategy should be done on the metastasized cells.
By definition, a cancer which has spread to another site via the circulatory or the lymphatic system (called metastasis) is malignant. If a surgeon takes it from a secondary site, it is malignant.
In the past, there were times that a cancer was so undifferentiated that to determine it's source was not possible. As science (particularly genetics) and technology continue to advance, tissue of origin is more easily determined.
Are there any differences when a surgeon takes tissue from secondary place rather then from primary place for morphological research?
Theoretically, it seems as it shouldn't, but it can happen at times, because, for example, a carcinoma may contain a mixed population of cancer cells, while the metastatic tumor may be of only one type.
For research purposes - which is different from diagnostics - it depends on the features most desired for research purposes.
In the past, there were times that a cancer was so undifferentiated that to determine it's source was not possible. As science (particularly genetics) and technology continue to advance, tissue of origin