We compared the RNase A level of patients with 11 kind of cancers with that of healthy controls, and found the serum RNase A level in patients with cervical cancer, esophageal cancer, kidney cancer, lung cancer, bladder cancer, pancreatic cancer, ovary cancer, liver cancer and gastric cancer are significantly down-regulated when compared with that of healthy controls (P<0.001), while the serum RNase level of breast cancer and colon cancer patients was not very significantly different from that of healthy individuals. The gene discussed is RNASE1; the disease is breast cancer.