In 1975, when I started performing screening mammograms, and before mammography came into wide use, the five-year survival rate for breast cancer had been stuck at 35 percent. This means that for every 100 women diagnosed with breast cancer, only 35 were alive at the end of five years.
|Note that detection of regional and metastatic disease has not decreased - we're finding an enormous amount of localized cancer. Over decades, this should lead to a lower rate of detection of invasive disease. Source|