Multi-gene panel testing has recently emerged as a safe and effective way to identify genetic mutations known to increase risk for breast cancer. Compared with earlier genetic tests, which required initial testing for BRCA1 and BRCA2 followed by subsequent testing for other cancer-related genes, multi-gene panel testing can evaluate up to 43 genes. At Breastlink, we recently conducted a study to see how multi-gene panel testing affected treatment and screening decisions in cancer survivors who had previously tested negative for BRCA1/2.

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How Does Management Change for Cancer Survivors with Positive Results?

For our study, we retrospectively collected data from 914 Breastlink patients who underwent multi-gene panel testing.  Patients were included in the study if they had a personal history of breast or ovarian cancer and had previously tested negative for BRCA1/2. A total of 187 patients met criteria and were included in the study.

Of the 187 patients included in the study, 10 patients (5.3 percent) were found to carry 11 pathogenic mutations. Genes affected included CHEK2¸ PTEN, BARD1, NF1, and RAD51C. One patients tested positive for a pathogenic mutation in both CHEK2 and BARD1. In each patient who tested positive, a change in management occurred.

Recommendations for genetic counseling and possible testing for certain family members were delivered to all of these patients. Screening with breast MRI was recommended to 8 of the 10 patients. Recommendations for early colorectal cancer screening, annual thyroid ultrasound, renal ultrasound and endometrial surveillance were delivered to patients with pathogenic mutations in PTEN. The possibility of risk-reducing mastectomy was also discussed with patients testing positive for PTEN mutations.

Preventing Second Invasive Cancers with Multi-Gene Panel Testing

Multi-gene panel testing potentially saved at least one patient from a second invasive cancer. The patient had initially been diagnosed with breast cancer at age 44 and was treated with lumpectomy, radiation and chemotherapy. At that time, she tested negative for BRCA1/2. When multi-gene panel testing was performed 19 years later, she tested positive for PTEN.

PTEN is associated with increased risk for multiple cancers. Risk for breast cancer in patients with pathogenic PTEN mutations exceeds 67 percent. In this instance, increased screening, including breast MRI, and surveillance were recommended. Breast MRI revealed an abnormality and, rather than receive a biopsy, the woman opted for risk-reducing prophylactic mastectomy. Following the surgery, occult ductal carcinoma in situ was discovered. This case illustrates how multi-gene panel testing in cancer survivors can prevent second invasive cancers.

The results of our study show how multi-gene panel testing can guide screening recommendations in cancer survivors, as well as in their family members. Advancements in technology and understanding of cancer biology can benefit survivors even years after their treatment has ended. As we learn more about the biology of cancer, we will undoubtedly become even more successful at personalizing treatment and risk management.

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