Editor’s note: Women with early-stage breast cancer have surgery to remove their tumors. They can choose between a mastectomy to remove the entire breast or a lumpectomy to remove the diseased part of the breast (breast conserving therapy, or BCT). Until now, it was thought that a mastectomy and BCT had similar results in terms of long-term survival for a patient. But a new study shows that BCT offers better survival for women who are PR-positive or ER-positive. Further studies are needed to figure out why. The researchers speculate it may have to do with the radiation treatment usually given just after BCT to keep the cancer from returning. Unfortunately, there appear to be socioeconomic barriers to receiving BCT instead of a mastectomy.
“When factoring in what is now known about breast cancer biology and heterogeneity, breast conserving therapy (BCT) may offer a greater survival benefit over mastectomy to women with early stage, hormone-receptor positive disease, according to research from The University of Texas MD Anderson Cancer Center.
“The study findings defy the conventional belief that the two treatment interventions offer equal survival, and show the need to revisit some standards of breast cancer practice in the modern era.
“The research was presented at the 2014 Breast Cancer Symposium by Catherine Parker, MD, formerly a fellow at MD Anderson, now at the University of Alabama Birmingham.”
The gist: Oncologists can sometimes check a patient’s tumor for specific genetic mutations that indicate how well different treatment options might work. Researchers recently discovered a genetic mutation found in some breast cancer tumors that could help oncologists predict how well the drug tamoxifen will work for a patient with ER-positive breast cancer. Further studies are needed to explore just how useful the discovery might be.
“Researchers have identified genes that may help predict whether a patient with estrogen receptor (ER)-positive breast cancer is likely to benefit from tamoxifen therapy, according to a study published in the July 15 issue of Cancer Research.
“Hendrika M. Oosterkamp, M.D., of The Netherlands Cancer Institute in Amsterdam, and colleagues conducted a large-scale loss-of-function genetic screen in ZR-75-1 luminal breast cancer cells to identify candidate genes for tamoxifen resistance.
“The researchers found that loss of function in the deubiquitinase USP9X prevented proliferation arrest by tamoxifen, but not by the ER downregulator fulvestrant. RNAi-mediated attenuation of USP9X stabilized ERα on chromatin in the presence of tamoxifen, and this caused a global activation of ERα-responsive genes driven by tamoxifen. A gene signature defined by differential expression after USP9X attenuation in the presence of tamoxifen was used to identify patients with ERα-positive breast cancer experiencing a poor outcome after adjuvant therapy with tamoxifen. Correlation of the gene signature with survival was not observed in patients with breast cancer who did not receive endocrine therapy.
” ‘Overall, our findings identify a gene signature as a candidate biomarker of response to tamoxifen in breast cancer,’ the authors write.”