Your second sentence is much more natural.
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michaeltingThe lack of a balanced diet is a factor in the development of cancer.I agree with Philip that this one is better, but I just want to add that it is also quite common to say 'risk factor' instead of just 'factor'.
ifJim.Success factor of business OrWe don't say either one of these. I'm not familiar with 'success factor', and certainly not with 'success factor for cancer'.
Success factor for business?