For at least forty years it has been conventional wisdom that women treated for breast cancer with either mastectomy or lumpectomy plus radiation need some form of additional treatment as “insurance” against the future development of metastatic disease. The debate has been: what treatment, how intensive does it need to be, and for how long should it be given. With the gradual technical improvements in mammography, smaller and smaller breast cancers are being discovered routinely. So, the question could be asked, do all of these women need additional treatment — typically chemo or powerful hormonal antagonists, or both — or can some be spared?
Some light has been shed on this question by a group from the University of California, San Fransicso Medical Center. Writing in JAMA Oncology Esserman and colleagues analyzed a large database from Stockholm, Sweden, in which women diagnosed with breast cancer from 1976 to 1990 were identified. Those women, who were post-menopausal and had no lymph-node involvement, were offered entry into a clinical trial in which half of them received tamoxifen, an anti-estrogen, and the other half received placebo. The authors retrieved actual tumor tissue from these women and studied it for the presence of seventy different gene mutations, using the Mammprint assy, a commercially available tool. They were able to identify a subset of women whose tumors had genetic profiles that were so favorable that they enjoy a likelihood of being cured of about 95%, whether or not they had received tamoxifen. 15% of the women in the study were deemed to be in this ultra-low risk group. The authors then comment that these women were diagnosed almost exclusively by physical exam, since mammography was not in vogue in Sweden in that era. They assert that the number of women with ultra-low risk tumors may actually be higher in the mammogram era, although they had no proof.
The big picture: a substantial percentage of women with newly diagnosed breast cancer have such a good prognosis that no further therapy is needed. US Oncologists should heed this message before recommending toxic treatment to everyone.