A study led by the University of North Carolina Lineberger Comprehensive Cancer Center has found that the breast tissue surrounding tumors may be used to scale future survival outcomes. This study is limited to women with estrogen receptor-positive breast cancer.
The National Cancer Institute reports that approximately 70% of breast cancers are estrogen receptor-positive.
Researchers identified and linked a particular gene expression pattern in the surrounding breast tissue of women with estrogen receptor-positive breast cancer, to lower 10 year survival.
This finding was published in the journal npj Breast Cancer.
There is belief that gene expression patterns will allow for the prediction of survival for patients. Gene expression patterns can be identified through the use of genomic sequencing.
The study’s first author, Melissa Troester, PhD., a UNC Lineberger Member, and an associate professor in the UNC Gillings School of Global Public Health Department of Epidemiology, stated that previous studies attempted to develop predictive biomarkers for the progression of cancer by focusing on tumor cells rather than the surrounding tissue. This study demonstrates that the microenvironment of the tumor as well as the tumor itself plays a role in the prognosis.
Multiple genomic characteristics of the surrounding tissue were analyzed by researchers in this study. Researchers focused on DNA mutations, repeat copies of genes, DNA methylation, and miRNA and Gene expression patterns. This study used samples from the Cancer Genome Atlas which is a multi-institution, collaborative effort.
Co-author Katherine Hoadley, PhD., explained that the surrounding tumor tissues are not as heavily monitored as the tumor itself. In many of the samples, evidence of tumor or changes in the tissue was found. There was no uniform genomic difference in the surround breast tissue to consistently identify defects, demonstrating the difficulty of determining differences.
Approximately 40% of the samples analyzed had some variation of DNA or RNA defect in the normal tissue outside the tumor margin. Genomic determining methods aided in the identification of cancer cells or defective normal cells. These cells were previously undetected using a microscope. The presence of cells with defects was not linked to a better or worse survival.
This study demonstrates the benefits of radiation therapy which has shown lower recurrence rates in women who chose breast-conserving surgery. It also reaffirmed that a wider surgical margin in surgery has no greater benefit as cells with genetic defects may be located as far as 4 centimeters away from the tumor.
Radiotherapy and adjuvant chemotherapy are more effective than a wider margin in surgery in eliminating cells with DNA defects, thus lowering recurrence rates.