[Analysis on the age of onset of malignant tumors in cancer registration areas in Zhejiang Province from 2000 to 2015].

Objective: To study the age of onset of malignant tumors in cancer registration areas in Zhejiang province from 2000 to 2015. Methods: Based on the incidence data of cancer from 14 national cancer registration areas in Zhejiang province between 2000 and 2015, the incidence rate, average/standardized average age of onset, and age-specific incidence proportion were calculated, and standardized by Segi's world population. The population was divided into 7 age groups (0-29, 30-39, 40-49, 50-59, 60-69, 70-79, ≥80 years old). The average age of onset and age-specific incidence proportion were analyzed by using a linear regression. The change trend of the proportion; the average annual percent change (AAPC) of the incidence rate was calculated by using the Joinpoint log-linear regression model. The birth cohort was constructed by using the standardized incidence rate and the year of onset of cancer, and the distribution characteristics of the age groups were described. Results: From calendar year 2000 to 2015, the average age of onset of malignant tumors in Zhejiang Province decreased from 59.7 to 57.6, with an average annual percent decrease of 0.09 year ( P= 0.033). After the merge of age groups, the standardized incidence proportion of 30-49 and ≥60 years old group standardization increased by an average annual change of 0.38% and decreased by an average annual change of 0.39%, respectively (both P values <0.001). The results of the log-linear regression model showed that the standardized incidence rate of the 30-39 and 40-49 years old age groups increased rapidly, with the AAPC (95 %CI ) about 5.2% (4.4%-6.0%) and 3.4% (2.5%-4.3%), respectively. The incidence rate of female increased rapidly, especially for 30-39 and 40-49 years old age groups with the AAPC about 6.2% (5.1%-7.2%) and 4.9% (4.0%-5.9%), respectively. The results of the birth cohort analysis showed that the population with different birth years in the same age groups saw an increasing trend with the increase of the birth year. Conclusion: The age of onset of malignant tumors in the cancer registration areas in Zhejiang Province is getting younger. The incidence rate and number of people with malignant tumors in 30-49 years old age group is evident. These characteristics are more obvious in female than that in male.