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New gene test could improve breast cancer treatment

Robin Wulffson MD's picture
Breast cancer treatment

All breast cancers are not the same. Some are more aggressive and thus require more intensive therapy. A new test, known as the genomic test, analyzes 12 genes from a woman's tumor; it can aid in predicting which cases are most likely to be aggressive, requiring both surgery and radiation, and which are likely to be slow-growing, requiring surgery alone. On December 6, Genomic Health, Inc. announced positive results from a clinical validation study of the test in patients with ductal carcinoma in situ of the breast (DCIS). The test results can help define which breast cancer treatment is most appropriate.

Based on this validation, Genomic Health plans to make the genomic test available to physicians and their DCIS patients on December 28, 2011. Its aim is to help the more than 45,000 American women a year diagnosed with DCIS by determining which type of breast cancer treatment they require. Some physicians regard the tumors to be very early breast cancers; however, others consider them to be precancers. Even though DCIS tumors are confined to the milk ducts, they have the potential to invade surrounding breast tissue.

Lead investigator Lawrence Solin, chairman of radiation oncology at Einstein Medical Center in Philadelphia noted, "This is a perfect example of how understanding the human genome can be translated into real life, to help real women… This is a very exciting advance." Prior to the development of the genomic test, physicians did not have a method, which could tell which DCIS cases are the most likely to spread, noted Dr. Solin. Women with the condition often are treated as if they have a more advanced cancer, with lumpectomy and radiation, and sometimes years of hormonal therapies.

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For DCIS, radiation reduces the risk of developing another tumor in the same breast; however, it does not improve survival, explained Steve Shak, Genomic Health's chief medical officer. Radiation therapy can destroy cancerous cells; however, it can burn the skin and damage the underlying heart and lung tissue. Undergoing radiation treatments also is time-consuming; it necessitates daily visits for five to seven weeks, noted Dr. Solin.

The study found that about 75% of women fall into the "low-risk" category, according to their gene profiles. After 10 years, only 5% of these women developed an invasive cancer in the same breast; this tumor was a more serious type, which had advanced beyond the milk ducts. The study also found that 11% of women fell into the "high-risk" group. Approximately 19% of these women developed an invasive breast cancer within 10 years.

Dr. Skaks noted that women and their physicians may want to use this information to guide their breast cancer treatment. He added that a similar test for women with early-stage invasive breast cancer has been available since 2004. That test, Oncotype DX, helps predict which patients may be able to avoid chemotherapy, contributing to a 20% reduction in a need for that therapy.

New medical tools often come with a hefty price tag and the genomic test is no exception: its current cost is $4,175. Despite that cost, if it results in the avoidance of radiation therapy, it would avoid the cost of that treatment, which can be more than $21,000. Beyond costs is the avoidance of harmful ionizing radiation.