Predicting Recurrence: Gene Expression Profiling

Research has revealed that a tumor's genetic profile is related to its behavior.  Activity of specific genes may indicate recurrence or metastasis.  Gene expression profiling allows for several genes in a tumor to be studied at the same time.  Profiling provides information on expression of genes that activate and suppress development of cancer cells.  Two new tests, Oncotype DX® MammaPrint®, are available for genetic profiling.  However, these tests are only valid for early-stage ER-positive cancer.

 

*Oncotype DX®

Readily available in hospitals, this test is performed in the tumor's paraffin blocks.  The test uses a tissue sample to evaluate activity of 21 genes, including ER, PR and HER2. Overall, 16 cancer genes and 5 control genes are used in the test.  A score ranging from 0 to 100 points expresses the activity of the gene.  A low score indicates low recurrence risk.  Recurrence within 10 years after diagnosis is more likely with a higher score.  Both ASCO and NCCN recommend this test to predict the risk of recurrence for newly diagnosed ER-positive cases that have not spread to the lymph nodes.  ASCO also states the test can identify patients who may be successfully treated with hormone therapy.  This may help avoid adjuvant chemotherapy.

 

*MammaPrint®

MammaPrint test studies 70 genes related to distant recurrence.  The test attempts to predict the risk of cancer recurring within 10 years of diagnosis.  MammaPrint requires fresh tumor tissue or tissue frozen shortly after removal from body.  In 2007, the US Food and Drug Administration cleared MammaPrint for use as a reliable predictor of surviving cancer.

Both types of treatments can be customized for specific risks of each individual woman.  Likelihood of occurrence, size and grade of the tumor are factors in the selection of treatment plans.  Those with low risk of recurrence can avoid chemotherapy, which can cause serious side effects.  Adjuvant chemotherapy can reduce likelihood of recurrence from high-risk cases.  Close monitoring of women with high risks of recurrence can ensure early intervention.

Although every individual insurance provider is different, Medicare and most private health insurance polices cover testing for ER-positive and node-negative breast cancer.