Factors at presentation influencing the prognosis in breast cancer.

Presentation data on 607 breast cancer patients treated by a variety of modalities at Guy's Hospital, London, have been analysed using the Cox proportional hazards model, to identify factors associated with length of overall survival. When deaths attributable to causes other than breast cancer were treated as censoring events, the significant factors were found to be stage, mode of treatment, menstrual status and tumour size. The analysis was repeated for the subgroup of 326 patients treated by modified radical mastectomy. Four variables: stage, age at menarche, menstrual status and age were found to be significantly associated with both overall survival and length of distant recurrence-free interval. These factors have been combined to create a prognostic index which has been used to define subgroups of patients with different prognosis. The index has been validated on a separate group of 457 modified radical mastectomy patients treated at the same hospital.