Tumors Can Change Biologically as They Progress

In many women with recurrent breast cancer, the estrogen receptor (ER), progesterone receptor (PR), andhuman epidermal growth factor receptor 2 (HER2) status of their tumors changes between treatment for the primary tumor and relapse, a large retrospective study has found. The findings, published June 18 in the Journal of Clinical Oncology, support previous studies that have also detected changes in these biomarkers during cancer progression.

These three biomarkers help doctors choose the best treatments for individual women. Therefore, tumors that recur in the breast or appear elsewhere in the body should be biopsied “as a routine procedure” because the results may influence treatment decisions, recommended the authors led by Dr. Linda Lindström of Cancer Center Karolinska in Sweden.

Dr. Lindström and her colleagues used information from pathology reports for 1,010 women treated at three hospitals in Stockholm, all of whom had biopsies taken from their primary and recurrent breast tumors. All three hospitals had stringent quality-control methods for verifying the accuracy of all three biomarkers.

Primary and recurrent tumors from 459 women were tested for ER expression. In almost 33 percent of those women, the ER status of the tumor changed (ER expression started or stopped) between treatment and relapse. More than 40 percent of the 430 women whose tumors were tested for PR expression had a change in PR status between treatment and relapse. And almost 15 percent of the 104 women whose primary and recurrent tumors were tested for HER2 expression had a change in HER2 status between treatment and relapse.

In women whose cancers relapsed multiple times, similar proportions of changes to biomarkers were observed.

http://www.cancer.gov/ncicancerbulletin/062612/page3