Is Lanzhou a place with a high incidence of cancer

Yes. At least it is higher than the national average:

In 2011, the areas covered by Gansu Province's tumor registration annual data were Lanzhou City and Wuwei City. The registration data showed that the cancer incidence rates in Lanzhou and Wuwei were 222.02/100,000 and 269.40/100,000, respectively, which were higher than the national averages of 23.23% and 38.83%, respectively. The analysis showed that the incidence rates of the two cities began to rise slowly in the age group of 25 years, reached a peak in the age group of 70 years, and then began to decline slowly. Among them, the incidence rate in Lanzhou City is lung cancer, followed by stomach cancer, colorectal cancer, liver cancer, breast cancer, cervical cancer, esophageal cancer, bladder cancer, gallbladder cancer and pancreatic cancer, with the top 10 cancers accounting for 73% of all malignant tumors. In Wuwei City, the first incidence rate is gastric cancer, followed by esophageal cancer, lung cancer, colorectal cancer, breast cancer, liver cancer, cervical cancer, lymphoma, uterine cancer and bladder cancer, the incidence rate of the top 10 cancers accounted for 87.3% of all tumors.