Although treatment recommendations have been advocated for all women with early breast cancer regardless of age, it is generally accepted that different treatments are preferred based on the age of the patient. The aim of this study was to assess the pattern of breast cancer surgery after adjusting for other major prognostic factors in relation to patient age. Data on cancer characteristics and surgical procedures in 31,298 patients with early breast cancer reported to the National Breast Cancer Audit between 1999 and 2006 were used for the study. There was a close association between age and surgical treatment pattern after adjusting for other prognostic factors, including tumor size, histologic grade, number of tumors, lymph node positivity, lymphovascular invasion (LVI), and extensive intraduct component. Breast Conserving Surgery (BCS) was highest among women aged <or=40 years (OR = 1.140; 95% CI: 1.004-1.293) compared to women aged 51-70 years (reference group). BCS was lowest in women aged >70 years (OR = 0.498, 95% CI: 0.455-0.545). Significantly more women aged <or=50 years underwent more than one operation for breast conservation (20.4-24.8%) compared with women aged >50 years (11.4-17.0%). Women aged >70 years were more likely to receive no surgical treatment, 3.5% versus 1.0-1.3% in all other age groups (<or=40, 41-50 51-70 years). There is an association between patient age and the type of breast cancer surgery for women in Australia and New Zealand. Women age <or=40 years are more likely to undergo BCS despite having adverse histologic features and have more than one procedure to achieve breast conservation. Older women (>70 years) more commonly undergo mastectomy and are more likely to receive no surgical treatment.