There are many misconceptions around this nutritive sweetener and I want to address a couple. First of all, HFCS is a mixture of fructose and glucose. The ratios of fructose to glucose are usually 55:45, but can also be 42:58 in HFCS42. For reference, table sugar (sucrose) is 50:50. This understanding alone can be enough to dispel any grave concerns that HFCS is an especially bad form of sugar.
However, I want to explicitly take on the notion that HFCS is in any way responsible for an increased risk of tumour formation. It is true that high HFCS consumption is correlated with higher risk of intestinal tumours, however this cannot be isolated from the context of the obese individuals consuming the sugar. Obesity increases the likelihood of developing many types of cancer, including colorectal cancer. When controlling for obesity it is clear that HFCS is not the problem. Fatter people eat more sugar-dense foods; this is not news.