Association between family history and onset age of cancer in China.

BACKGROUND

Family history (FH) of cancer is an established risk factor for early onset of cancer. However, reliable estimates on the difference in onset age between familial and sporadic cancers remain scarce in the Chinese population.

METHODS

This multicenter, hospital-based, cross-sectional study included 23 hospitals across 12 provinces in China. Patients diagnosed with cancers of the lung, stomach, esophagus, or colorectum between January 1, 2016 and December 31, 2017 were identified. Detailed information on sociodemographic characteristics, lifestyle factors, stage at diagnosis, and onset age was collected. We analyzed the association between FH and onset age across different cancer types using quantile regressions.

RESULTS

Among 41,072 eligible patients, 3054 (7.44%) reported a first-degree FH of cancer, and they were diagnosed at younger ages than those without FH (median difference: -1.19, 95% confidence interval [CI]: -1.59 to -0.79). Stratified by cancer type, the most pronounced difference was observed in colorectal cancer (median difference: -2.25, 95% CI: -3.31 to -1.19). Failure to account for lead time bias resulted in an overestimation of the FH effect, ranging from 3.4% to 15.4% across cancer types. Quantile regression analysis revealed that the impact of FH on age at diagnosis was more pronounced at the upper tail of the age distribution for all cancers combined and for each cancer type individually.

CONCLUSIONS

Our findings suggest that FH of cancer is associated with the early onset of lung, stomach, esophageal, and colorectal cancers in China. Cancer screening at earlier ages is needed for individuals with an FH.