Interestingly, in all tumor entities SFRP2 methylation was detected with a high frequency of > 50% of cancer patients, ranging from 52% in lung cancer to 96% in gastric cancer, which suggests that SFRP2 methylation might potentially be useful as a ubiquitous pan-tumor marker in cancerous tissues, and possibly also in body fluids. Here, SFRP2 is linked to lung cancer.