There is no proof that stress directly causes cancer
There have been many correlations drawn between cancer and stress as a root cause of it. There is absolutely no scientific proof that stress can cause lymphoma or any other type of cancer. Though it can be an indirect cause (due to risky behaviors people sometimes engage in to feel stress relief), it can not be proven to be a direct cause of anything. Though there is no sign that researchers will stop looking for a direct correlation between chronic stress sufferers and cancer patients anytime soon, it is safe to say that learning healthy coping methods are best for everyone.