[Clinical features and prognostic analysis of female breast cancer in different diagnosed ages]

Objective: To evaluate 5-years breast cancer-specific survival (CCS) by age, and the relationship of age at diagnosis and the risk of breast cancer mortality. Methods: Medical records of 3 470 resident patients diagnosed with primary, invasive female breast cancer between January 1, 2006 and December 31, 2010 in four hospitals in Beijing were reviewed and collected. All patients were followed up until December 31, 2018 to acquire survival outcome. Five-years breast CCS of the five subgroups was estimated by the life-table method. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of different levels of age stratification and breast cancer mortality, and restricted cubic spline (RCS) model was used to detect the dose-response relationship. Results: The median diagnosis age among 3 470 female breast cancer patients was 53.2 years. There were 1 289 patients in the age-group of 45~54 years, with the highest proportion of 37.15%. However, only 126 patients occurred in the age-group of less than 35 years, with the lowest proportion of 3.63%. A total of 528 (15.22%) patients died of breast cancer during the study period. Overall 5-year CCS was 90.72% (95%CI: 89.74%~91.70%), 88.68% (95%CI: 83.09%~94.27%) and 87.05% (95%CI: 84.27%~89.82%) for all of the patients, aged less than 35 years and those aged 65 years and older. Compared with patients with diagnosis age of 45~54 years, the multivariate-adjusted HRs for breast cancer mortality associated with patients in age-group of <35 years and those in the age-group of ≥65 years were 1.72 (95% CI: 1.06~2.81) and 1.89 (95% CI: 1.43~2.49), respectively. In addition, patients aged ≥65 years had significantly higher risk of breast cancer mortality in Luminal subtypes, with HR of 1.70 (95% CI: 1.17~2.46) for Luminal A breast cancer and HR of 3.84 (95% CI: 1.74~8.49) for Luminal B breast cancer. RCS analysis exhibited a non-linear ( "J-shaped" ) relationship between diagnosis age of female breast cancer and the risk of breast cancer mortality (nonlinear P<0.000 1). In addition, patients aged ≥65 years had significantly higher risk of breast cancer mortality in Luminal subtypes, with HR of 1.70 (95% CI: 1.17~2.46) for Luminal A breast cancer and HR of 3.84 (95% CI: 1.74~8.49) for Luminal B breast cancer. RCS analysis exhibited a non-linear ( "J-shaped" ) relationship between diagnosis age of female breast cancer and the risk of breast cancer mortality (nonlinear P<0.000 1). Conclusion: Age at diagnosis is an important prognostic factor for female breast cancer, with worse outcome for both young and old patients.