Age effects on survival from early breast cancer in clinical settings in Australia

Abstract

BACKGROUND: The study aim was to determine whether age is an independent risk factor for survival from early invasive breast cancer in contemporary Australian clinical settings. METHODS: The study included 31 493 breast cancers diagnosed in 1998–2005. Risk of death from breast cancer was compared by age, without and with adjustment for clinical risk factors, using Cox proportional hazard regression. RESULTS: Risk of breast cancer death was elevated for cancers of larger size, higher grade, positive nodal status, oestrogen receptor negative status, vascular invasion and multiple foci. Ductal lesions presented a higher risk than other lesions. Adjusting for these factors, the relative risk of breast cancer death (95% confidence limits) was lower for 40–49-year-olds at 0.80 (0.66, 0.96) than for the reference category under 40 years, but higher for 70–79-year-olds at 1.64 (1.36, 1.98) and women aged 80 years or more at 2.19 (1.79, 2.69). The risk for 50–69-year-olds and women under 40 years was similar. Risk-factor adjustment reduced the difference in risk between the reference category under 40 years and 40–49-year-olds, largely eliminated the lower relative risk for 50–69-year-olds, and increased the relative risks for women aged 70–79 years and older. DISCUSSION: Survivals in women under 40 and over 70 years of age are poorer than for 40–69-year-olds. Research is needed into the best treatment modalities for younger women and older women with co-morbidity.