New York, Dec 15 : Researchers have confirmed that a group of industrial chemicals called per- and polyfluoroalkyl substances (PFAS), also known as "forever chemicals", contributes to colon cancer metastasis -- spread to other parts of the body. The research, published in the journal Environmental Science & Technology, showed that the forever chemicals spurred cancer cells in the lab to migrate to new positions, an indication that the chemicals could contribute to cancer spread. Colon cancer or colorectal carcinoma (CRC) is more common among firefighters than the general population and they are heavily exposed to PFAS at work. About 80 per cent of CRC cases are thought to be related to environmental exposure of some kind, the researchers said. No studies have addressed the relationship between PFAS and colorectal carcinoma (CRC), said Jie Zheng, a postdoctoral associate at Yale University. In a series of experiments, the authors studied how CRC cells react to being immersed in a PFAS solution for up to seven days. They observed increased cell motility with exposure and found metabolic changes that were consistent with cancer metastasis. Results agreed with current knowledge about CRC metabolism, spread, and prognosis, amounting to evidence that the chemicals can induce metastasis. To investigate the metabolic profile of CRC cells after PFAS exposure, the study focused on perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). Both have been used in firefighting foam and many other products, and have been classified as carcinogenic to humans. The team used two CRC cell types from a line called SW48. One type consisted of cells with an unmutated or "wild-type" KRAS gene; in the other, the KRAS gene carried a common mutation associated with an especially deadly type of colon tumour in women. The cells formed into tiny balls called spheroids. The researchers found that bathing spheroids in the chemicals boosted the cells' migration ability. They showed a tendency to spread and to penetrate membranes. In another experiment, researchers grew the cells as a flat, two-dimensional layer, then drew a scratch down the middle, separating half of the cells from the other half. When they added PFAS, the cell lines grew and migrated back together again. "It doesn't prove it's metastasis, but they have increased motility, which is a feature of metastasis," said Caroline Johnson, Ph.D., associate professor of epidemiology at Yale. Some changes suggesting metastatic potential were more pronounced in the KRAS-mutated line. That could mean that cancers with this mutation may be especially prone to spread after exposure to these chemicals. /IANS