Five year breast cancer survival
rates do not give an accurate
picture of progress against
Because breast cancer takes many years, sometimes even decades, to develop and spread throughout the body, breast cancer survival statistics, particularly five-year survival data, do not accurately portray the impact of breast cancer, or the progress or lack of progress over time. Only mortality rates can give an accurate picture of the impact of the disease since it can measure death rate in the population over a lifetime.
It is often repeated that 98% of women with early stage breast cancer are alive at five years after diagnosis. However, an estimated 20% to 30% of women will have a recurrence of their disease, and may go on to die of the disease, but are included as survivors in these five-year survival statistics. We still do not know how to prevent recurrence and metastasis for most women or how many of the women reported to have survived five years will go on to have a recurrence.
In addition, survival statistics are skewed by screening programs. The more screening there is, the more breast cancers are found. But it does not follow that more lives are saved. Because breast cancer can be slow-growing, finding breast cancer through screening mammography often increases the time women know they have breast cancer, but may not have any impact on final outcomes. Again, following trends in breast cancer mortality rates, rather than survival at five years after diagnosis, is the only way to get an accurate picture of the toll of breast cancer and progress made.