Survival of breast cancer patients related to incidence risk factors

Variation in survival of breast cancer patients has been examined for relationship to three demographic variables known to affect incidence rates—geography, socioeconomic status and age at birth of first child. Three-year relative survival ratios in two areas with high incidence rates (Boston, USA and Glamorgan, Wales) were 75.3% and 66.4%, respectively. In an area with a low incidence rate (Tokyo, Japan) the ratio was 85.6%. The overall survival ratios differed significantly between areas, but the pattern is not such as to suggest a consistent correlation — either positive or negative — with incidence rates. The differences in survival ratios between areas were not explained by differences in the extent of disease at diagnosis. Survival ratios did not vary consistently with socioeconomic status, as measured by duration of schooling. Neither childbearing nor age at which porous patients first became pregnant was related to probability of survival.