Long term survival analysis: the curability of breast cancer.
ABSTRACT Methods of survival analysis for long-term follow-up studies are illustrated by a study of mortality in 3878 breast cancer patients in Edinburgh followed for up to 20 years. The problems of life tables, advantages of hazard plots and difficulties in statistical modelling are demonstrated by studying the relationship between survival and both clinical stage and initial menopausal status at diagnosis. To assess the 'curability' of breast cancer, mortality by year of follow-up is compared with expected mortality using Scottish age-specific death rates. Techniques for analysing such relative survival data include age-corrected life tables, ratio of observed to expected deaths and excess death rates. Finally, an additive hazard model is developed to incorporate covariates in the analysis of relative survival and curability.
- Clinical oncology 07/1979; 5(2):123-33. · 2.85 Impact Factor
- National Cancer Institute monograph 10/1961; 6:101-21.
- [show abstract] [hide abstract]
ABSTRACT: A retrospective analysis was made of 3878 cases of breast carcinoma first seen in Edinburgh from 1954 to 1964. During this time there was a policy to treat breast cancer by simple mastectomy and x-ray therapy, and over 90% of cases classified as international stages I and II were so treated. The mortality in these women was compared with that in an equivalent normal population using Scottish national age-specific death rates. For every year of follow-up within 20 years of initial treatment there was an excess mortality from all causes. There was an overall excess mortality of 58% among patients with breast cancer 15-20 years after initial treatment, and 20 times more deaths occurred in this period from breast cancer than in a normal population. For patients disease-free after 15 years there was still a 28% excess mortality from all causes. Factors known to be of major prognostic significance for five-year survivorship had less influence than might have been expected when the ratio of observed to expected deaths was considered for longer periods of follow-up. The effect of clinical staging (I, II, or III), though initially marked, largely disappeared by the 10th year of follow-up, and after allowing for age there was no evidence beyond 10 years of an effect on survival of the original stage of the disease. Similarly, the effect of tumour size on survival disappeared after 10 years. Women who were premenopausal at presentation still had a significant excess of deaths in the fourth quinquennium of follow-up. In the menopausal and postmenopausal groups combined there was still a small non-significant excess of deaths from all causes after 15 years but this almost disappeared when patients who had already relapsed were excluded. In terms of overall mortality only patients who have undergone the menopause before presentation and who are disease-free 15 years after primary treatment may prove to be cured by conventional techniques such as simple mastectomy and postoperative radiotherapy.British medical journal 12/1979; 2(6200):1247-51.