This study found significant differences in breast cancer survival rates across age groups.

Results indicate an increased risk of death from breast cancer in women less than 40 years of age at the time of diagnosis, compared with women aged 40 to 49. Women under 40 were more likely to have more aggressive forms of cancer (high grade tumours), tumours originating in the milk ducts (ductal tumours), large tumours, cancer spread to the blood or lymphatic vessels (vascular/lymphatic invasion) and tumours that do not need the hormone oestrogen to grow (oestrogen receptor negative). However, adjusting survival rates to take into account these and other clinical factors known to affect survival did not fully explain the increased risk for younger women. There may be other factors involved that were not included in this study.

A lower risk of death from breast cancer was found in patients aged 40 to 49 and those aged 50 to 69. When the figures were adjusted to remove the effects of various clinical factors, such as those above, the adjusted risk for patients aged 50 to 69 rose to a level similar to the risk in patients aged under 40. The lower risk originally found may be due to the breast screening program which targets this age range. Breast screening aims to detect cancer at an early stage to increase the likelihood of favourable clinical factors and therefore survival.

An increased risk was also found in women aged 70 or more. This may reflect a higher level of illness and frailty in these women, in addition to the cancer, which would reduce the patient's ability to endure treatment. Adjuvant therapy such as radiotherapy, chemotherapy and immunotherapy are less commonly received for older patients.

More research is needed into factors which affect survival from breast cancer in women under 40 and those 70 and older to determine the best options for care.