When the injections were reduced to every other week for a PEGylated IFNb, the results showed that there was still a more significant decrease in the rate of tumor growth using PEGylated IFNb containing a branched 40 kDa PEG moiety, even when compared to the rate of tumor growth for mice injected three times a week with the commercially available (non-PEGylated) form of IFNb. This evidence concerns the gene IFNB1 and neoplasm.