Objective  To analyze the incidence and trend of incidence of malignant tumors in Ningbo from 2011 to 2021.

  Methods  The incidence data of cancer were collected from the cancer registry system of Ningbo. According to international classification of diseases (ICD10) and data of registered population, the crude incidence rate, age and site specific incidence rate of malignant tumors were calculated, further standardization was performed. The age-standardized rate was adjusted by Chinese standard population in 2010 (ASIRC) and world standard (Segi 1960) population (ASIRW). Software Joinpoint Regression Program 4.9.0.0 was used to analyze the trend of incidence. The average annual percent change (AAPC) was calculated to indicate the incidence change. The trend of average onset age and standard average onset age according to table of frequency distribution was analyzed by a linear regression model.

  Results  The AAPC of age-standardized rate of malignant tumors based on ASIRW in Ningbo was 3.19% (2.49%–3.90%), which was higher in women (5.53%) than in men (1.07%) (P=0.001). The AAPC of age-standardized rate of malignant tumors based on ASIRW was 4.78% in rural area and stable in urban area in Ningbo. The incidence rate increased with age, while the largest AAPC was in 20–29 years old age group. The standard average onset age decreased about 0.38 years. In men, the age-standardized incidence rate of lung cancer, colorectal cancer, thyroid cancer, prostate cancer, lymphoma based on ASIRW increased, while the age-standardized incidence rate of stomach cancer, liver cancer and esophagus cancer based on ASIRW decreased. In women, the age-standardized incidence rate of lung cancer, thyroid cancer, breast cancer, colorectal cancer, uterus cancer based on ASIRW increased, while the age-standardized incidence rate of stomach cancer and liver cancer based on ASIRW decreased.

  Conclusion  The incidence rate of malignant tumors in Ningbo was higher than national average levels. The average age of the cases was young. It is necessary to strengthen the prevention and control of malignant tumors in women and in rural area. Lung cancer, colorectal cancer and breast cancer should be priorities in the prevention and control.