Stanford Scientists Identify Relative Risk of 25 Cancer Associated Genes

Highlights:

Numerous genes have been identified to increase the risk of cancer; however, not everyone who has the mutation develops cancer.
The relative risk of 25 cancer genes identified by Stanford scientists will help in determining individual risk of developing cancer among individuals who carry the gene mutation.
Risk assessment can be used to provide personalized care for high-risk patients and to determine the type of care.

Genome wide association studies were used to identify gene mutations that are known to increase the risk of cancer. However, patients who find out that they have the mutation may not want to know that they have an increased risk of cancer. Moreover, it is difficult to identify which patient will actually develop the disease condition, which raises the anxiety level of individuals and affects their ability to choose their treatment. A research team from Stanford University School of Medicine along with Fox Chase Center studied 95,561 women to help interpret the results of genetic testing.

Interpreting the Genetic Test Results

The scientists involved in the study analyzed the family history, genetic test results and the presence of disease among the study participants who underwent genetic testing. The genetic tests were conducted to identify the presence of 25 mutations that are found to lead to the development of breast and ovarian cancer. Some of the study participants had cancer while others did not.

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‘Women who carry the cancer risk gene mutations were at 2 to 40 times higher risk of developing cancer than women who did not carry the mutation.’

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The study found that

7% of the women carried a minimum of one of the mutations

Extent of Risk

This study was aimed at

Providing the degree of risk which will help women and their physicians assess the risk of cancer.
Preventing confusion regarding the prospect of developing cancer.
Providing clarity to regulatory bodies like the American Cancer Society who recommend when further tests should be taken, or how frequently.

Dr. Allison Kurian, Stanford University’s associate professor of medicine and of health research and policy, and the lead author of the study, said that the results could be used to personalize risk estimation as well as to tailor make recommendations for preventive care. The insight gained into the development of cancer will help patients as well as physicians cope better with care.

Cancer Management Based On Risk

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Cancer management is a combination of various therapeutic strategies that include chemotherapy, radiation therapy as well as hormone treatment. An example stated by Dr. Kurian was that women at high risk would prefer mastectomy while women at low risk would prefer frequent intensive screening procedures like breast magnetic resonance imaging.

Relevance of a Mutation

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Genetic testing is now accessible for many women and, most often, women are tested for a number of gene variations or mutations that are known to increase the risk for cancer. However, there is little understanding about the exact effect of these gene variations.

Certain well-known genes like BRCA1 and BRCA2 are known to increase the risk of cancer, while there are numerous other genes that have been implicated in the condition but have not yet been substantiated with large scale studies to understand the extent of their risk.

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Testing 25 Cancer Associated Mutations

95,561 cancer patients and healthy women who were matched according to their age and ethnicity were included in the study, and their genetic results assessed. A total of 25 cancer-associated genes formed the panel of gene variations that were tested. The family history of cancer was gathered to determine the relative risk of developing the disease condition based on the presence of the mutation.

The study was published in the journal JCO Precision Oncology and detailed the relevance of a mutation and the risk of cancer.The study results showed that

8 genes were found to have a positive association with the development of breast cancer.
11 genes were found to have a positive association with ovarian cancer.
The risk of developing cancer for women who carried the gene mutations was found to be 2 to 40 times higher than in women who did not have the mutations.

Strength of Association

A number of small case-control studies have been carried out to identify genes that are associated with cancer risk; however, this is one of the largest studies conducted till date, and the results will help in improving personalized care for cancer patients.

Based on the relevance to smaller studies, this comprehensive study

Substantiated the results of smaller studies, strengthening the association between the gene mutation and the risk of developing cancer.
Helped in gaining better insight into the gene mutation; for example, a gene called the ATM gene that was for long believed to increase the risk for breast cancer was now found to increase the risk for ovarian cancer.
Three mutations that were earlier found to increase the risk for breast cancer were now found to have little effect.

Though the risk of ovarian cancer among individuals who carried a mutation in the ATM gene was identified among a numerically small population, it was statistically significant, according to Dr. Kurian. This was a novel gene marker for the risk of ovarian cancer and it has not been recorded earlier.

Precision Medicine in Cancer Care

Precision medicine plays an important role in cancer diagnosis, treatment and care. There are specific gene mutations that are known to increase the risk of cancer and analyzing these genes will help determine the level of risk.

Apart from the risk of developing the disease condition, they can also be used for determine the type of treatment, constituting precision medicine, for example

Patients with chronic myelogenous leukemia who have a variant enzyme produced by a fused variant of 2 genes can be treated using the drug Imatinib (Gleevec), which blocks the enzyme production.
Breast cancer patients who have a genetic profile known as HER-2 positive can be treated with the breast cancer drug Trastuzumab (Herceptin).
Lung cancer patients with certain EGFR mutations respond to the drugs Erlotinib (Tarceva) and Gefitinib (Iressa).

Personalized medicine is the future of care for cancer patients and the current study by scientists from Stanford University that analyzed the extent of risk afforded by previously studied gene variations and cancer risk, will help improve care. Cancer is a heterogeneous disease, with significant variation in response from one patient to another; such studies that focus on identifying the extent of risk of variant genes will help in designing improved personalized care.

Reference:

Impact of Cancer Genomics on Precision Medicine for the Treatment of Cancer - (https://cancergenome.nih.gov/cancergenomics/impact)

Source-Medindia