What are metastasis made of ??

According to Tullio Simoncini metastasis occur as a consequence of fungi entering the blood stream and settling down elsewhere in the body forming new colonies (= metastasis). According to his theory the cells surrounding these metastatic colonies are reactive cells originating from the organ where the metastasis is. To understand why this is completely wrong you should try to understand this simplified description of cancer biology:
Cancer cells try to imitate the cells from which they originate. Bowel carcinoma cells try to imitate cells lining the bowel, breast cancer cells try to imitate breast gland cells and so on. If Simoncinis theory was correct, the microscopic examination of metastasis would reveal fungal colonies surrounded by "reactive" cells from the organ in which the metastasis is found. In reality the metastasis is made of cells similar to the location of the cancer itself. A common task for a pathologist is to examine a metastatic lesion and provide information about the localisation of the cancer. The photo below shows a cancer, where a vein has been invaded by cancer cells - Not fungi.

The denial of the metastatic spread of cancer cells is not only related to  Simoncini. Other alternative practitioners make the same erroneous claim.

Back to simoncinis claims

The photo below is of a liver biopsy from a metastasis. As mentioned above cancer cells try to imitate the cells from which they originate. A special technique called immunohistochemistry makes it possible to detect the presence of protein structures. If a protein structure is present it will stain brown. This biopsy has been stained for a protein called cytokeratin 20. This protein is present in the cells lining the large bowel (and the cancer cells that are originated from them. Liver cells do not contain cytokeratin 20. The cancer cells in this liver are not reactive liver cells. Furthermore it is a fair conclusion that these cells originate from the colon cancer this patient turned out to have (it was the examination of the metastatic lesion that led to the localisation of the cancer).