Factors influencing the effect of age on prognosis in breast cancer: population based study

Objective To investigate whether young age at diagnosis is a negative progn ostic factor in primary breast cancer and how stage of disease at diagnosis and treatment influences such an association. Design Retrospective cohort study based on a population based database of p atients with breast cancer containing detailed information on tumour charac teristics, treatment regimens, and survival. Setting Denmark. Subjects 10 356 women with primary breast cancer who were less than 50 years old at diagnosis. Main outcome measures Relative risk of dying within the first 10 years afte r. diagnosis according to age at diagnosis after adjustment for known progn ostic factors and expected mortality. Results Overall, young women with low risk disease who did not receive adju vant treatment had a significantly increased risk of dying; risk increased with decreasing age at diagnosis (adjusted relative risk: 45-49 years (refe rence): 1: 40-44 years: 1.12 (95% confidence interval 0.89 to 1.40): 35-39 years: 1.40 (1.10 to 1.78); < 35 years: 2.18 (1.64 to 2.89). However, no si milar trend was seen in patients who received adjuvant cytotoxic treatment. The increased risk in younger women who did not receive adjuvant treatment compared with those who did remained when women were grouped according to presence of node negative disease and by tumour size. Conclusion The negative prognostic effect of young age is almost exclusivel y seen in women diagnosed with low risk disease who did not receive adjuvan t cytotoxic treatment. These results suggest that young women with breast c ancer on the basis of age alone, should be regarded as high risk patients a nd be given adjuvant cytotoxic treatment.