Women are increasingly more likely to have the less aggressive form of breast cancer, hormone-receptor-positive (ER-positive and PR-positive), with smaller tumors, according to research published in the March 2009 British Journal of Cancer.
Scottish researchers compared 420 tissue samples from 1984 and 1986 with 653 from 1996 and 1997. In that ten-year span, they found that the proportion of estrogen-positive cancers rose from 64.2 percent to 71.5 percent. More grade one tumors were also diagnosed.
The good news here is that these cancers are easily treatable, offering a more positive prognosis than estrogen-negative cancers.
Lifestyle changes could be one influence, as could better screening. As usual, doctors say more research is necessary.
Brown, SBF, Mallon, EA, Edwards, J, Campbell, FM, McGlynn, LM, Elsberger,B, and Cooke,TG, “Is the biology of breast cancer changing? A study of hormone receptor status 1984–1986 and 1996–1997, British Journal of Cancer (2009) 100, 807–810. doi:10.1038/sj.bjc.6604934 www.bjcancer.com