There’s no standard medical definition for precision medicine (also called personalized medicine). So, you may hear this term used in different ways.
In general, precision medicine describes tailoring (or adapting) the treatment of a disease (such as breast cancer) to give the most effective treatment for each person’s disease.
To do this, it uses information that can include:
The goal of precision medicine is to give the most effective treatment for each person’s breast cancer. This involves:
Some factors that help personalize treatment plans are related to an individual. For example, some treatments are chosen based on whether or not a woman has entered menopause.
Most factors that help personalize treatment however, are related to the breast cancer itself.
Breast cancers differ in many ways, especially at the molecular (cell) level. Factors related to the tumor give information on prognosis and help personalize treatment to give the most benefit to each person.
Although treatment is becoming more personalized, we cannot predict how any one person will respond to a certain treatment.
Treatment is personalized based on the groups a person belongs to (such as people with HER2-positive breast cancers, people with lymph node-positive breast cancers, women who are premenopausal and other groups) rather than to a specific person.
The results of clinical trials show us which therapies are most effective in which groups of people. If a certain therapy is effective in a group you belong to, then your treatment plan can be personalized to include that therapy.
For example, clinical trials have shown the targeted therapy trastuzumab (Herceptin) lowers the risk of recurrence of HER2-positive breast cancers. If your tumor is HER2-positive, your treatment plan is usually personalized to include trastuzumab.
Learn more about factors that affect treatment and prognosis.
Information related to your breast cancer helps personalize your treatment plan.
When breast cancer is diagnosed, a pathologist studies some of the tumor tissue under a microscope and runs some tests on the tissue.
The pathologist’s findings describe features of the tumor such as size, type and grade, as well as other factors that help plan your treatment.
For example, all tumors are tested for:
Tumor profiling tests (using gene expression profiling tools) give information about the genes in cancer cells. Sometimes the genetic profile of a tumor can help guide treatment.Tumor profiling is currently used to help make treatment decisions in some people with estrogen receptor-positive cancers. It can help decide whether or not a person needs chemotherapy in addition to hormone therapy to best treat the breast cancer.Sometimes the genetic profile of a tumor can help guide treatment.
Three tumor profiling tools recommended by the American Society of Clinical Oncology (ASCO) are [62-63]:
Learn more about factors that affect prognosis and treatment.
Many new targeted therapy drugs for breast cancer are under study.
As with most new drugs, these therapies are first studied in the treatment of metastatic breast cancer.
Findings from these studies determine whether new drugs will become part of the standard of care for metastatic breast cancer. If so, they may go on to be studied for the treatment of early breast cancer.
Researchers continue to study ways to personalize therapies to best treat each person and each breast cancer.
Targeted therapy drugs are designed to attack certain cancer cells or certain cellular pathways.
Targeted drug therapies for early and locally advanced breast cancer include trastuzumab and pertuzumab. For metastatic breast cancer treatment, more targeted therapies are available including tyrosine-kinase inhibitors and poly (ADP-ribose) polymerase (PARP) inhibitors.
There are challenges though with targeted drug therapy research.
For example, some drugs target certain cellular pathways involved in both cancer cell functions and normal cell functions. So, while these drugs may block cancer cell functions and cancer growth, they may also harm healthy cell functions and cause unintended side effects.
Researchers are looking for ways to have such drugs affect only cancer cells and leave healthy cells unharmed.
Tyrosine-kinase inhibitors block tyrosine kinase enzymes, which are important in certain cancer cell functions.
Tyrosine-kinase inhibitors include neratinib (Nerlynx), which is FDA-approved for the treatment of HER2-positive early breast cancer, and lapatinib (Tykerb), which is FDA-approved for the treatment of HER2-positive metastatic breast cancer.
Other tyrosine-kinase inhibitors are under study and are only available in clinical trials.
PARP inhibitors block the PARP enzyme, which is involved in DNA repair.
Some chemotherapy drugs damage DNA. Adding a PARP inhibitor to these chemotherapy plans may lower the chances the cancer cells become resistant to the chemotherapy.
PARP inhibitors appear to hold the most promise for metastatic breast cancer in people who have a BRCA1 or BRCA2 gene mutation . The PARP inhibitor olaparib is now FDA-approved for treating metastatic breast cancer in women who have a BRCA1/2 gene mutation.PARP inhibitors are under study for treating early breast cancer. For people with early breast cancer, they are only available in clinical trials.
We may understand how a drug works (and which cancer cell functions it targets), but we still need to learn exactly who the drug helps.
For example, the drug bevacizumab (Avastin) blocks angiogenesis (the growth of new blood vessels). Without a blood supply, cancer cannot grow.
While studies show bevacizumab does not offer a treatment benefit for all people with metastatic breast cancer, researchers are still studying whether it may benefit some people with certain types of metastatic breast cancer.
Learn more about targeted therapies.
Learn more about emerging areas in targeted drug therapies for metastatic breast cancer.
Molecular differences in breast tumors may help guide treatment and the development of new targeted therapies.
Most studies divide breast cancers into 4 molecular subtypes:
Although mainly used in the research setting, these subtypes may be useful in tailoring treatments and developing new therapies in the future.
Learn more about molecular subtypes of breast cancer.
Tumor profiling tests (using gene expression profiling tools) give information about the genes in cancer cells and may help us learn more about differences in breast cancers.
Tumor profiling is currently used to help make treatment decisions in some people with estrogen receptor-positive breast cancer. It can help decide whether or not a person needs chemotherapy in addition to hormone therapy to best treat the breast cancer.At this time, the 3 tumor profiling tests recommended by the American Society of Clinical Oncology (ASCO) are [62-63]:
Other tools are mostly limited to the research setting. Researchers are working to address the technical limits of these tools.
Learn more about tumor profiling.
Although still under study, your genes and personal characteristics (such as lifestyle factors) may help guide your breast cancer treatment.
At this time, personal genetic information is not used to make treatment decisions.
However, some personal factors help guide treatment choices.
For example, for a woman whose treatment plan includes hormone therapy, whether or not she is postmenopausal guides her drug options.
After menopause, women can take tamoxifen or an aromatase inhibitor. Before menopause, women can only take tamoxifen (unless the aromatase inhibitor is combined with ovarian suppression).
As we increase our understanding of how a person’s genes affect breast cancer, we can use that knowledge to personalize treatments.
Being able to identify genes that might predict a person’s response to a specific therapy would help inform and personalize treatment decisions.
For example, PARP inhibitors can be more effective in treating metastatic breast cancers in women who have a BRCA1 or BRCA2 gene mutation compared to cancers in women without these mutations. The PARP inhibitor olaparib is now FDA-approved for treating metastatic breast cancer in women who have a BRCA1/2 gene mutation.
Lifestyle factors and other personal characteristics may also help personalize treatments in the future.
These topics are under active study.
Findings from clinical trials continue to improve breast cancer treatment.
New therapies are being studied in clinical trials. Whether a new therapy or test becomes part of standard breast cancer care depends largely on clinical trial results.People volunteer to take part in these research studies. If you have breast cancer, we encourage you to consider joining a clinical trial.Whether a new therapy or test becomes part of standard breast cancer care depends largely on clinical trial results.
If you have breast cancer, we encourage you to consider joining a clinical trial.
Susan G. Komen® in collaboration with BreastCancerTrials.org offers a custom matching service to help you find a clinical trial that fits your needs.
If you or a loved one needs information or resources about clinical trials, call our Clinical Trial Information Helpline at 1-877 GO KOMEN (1-877- 465- 6636) or email at firstname.lastname@example.org.
Learn more about clinical trials.
*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date at this time.
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