Extending hormonal therapy to treat breast cancer.

Approximately two-thirds of all breast cancer is positive for estrogen receptors (ER) and progesterone receptors (PR). These receptors are the proteins in the cell that estrogen and progesterone bind to. This binding has to occur before estrogen and progesterone can act on the cell. In breast cancers that are ER and/or PR positive, the presence of these receptors allows hormones to stimulate the cancer cell, thus essentially fueling the growth and survival of the cancer. Medications that block either the body’s production of estrogen and progesterone, or the action of these hormones on the cell, are a crucial part of the treatment for breast cancer patients whose tumors are ER and/or PR positive.

The optimal duration of hormonal therapy has been the subject of many studies over the years. Early studies with tamoxifen (a drug which prevents estrogen from binding to its receptor) indicated that treatment should continue for at least five years, because shorter durations of treatment were clearly inferior. However, more definitive studies which were reported this decade clearly showed that extending the length of tamoxifen use from five years to ten years reduced the risk of breast cancer recurrence.

Another approach to hormonal therapy for breast cancer, which is used only in postmenopausal women, is the use of any of the drugs which belong to the class known as aromatase inhibitors. Even after menopause, the body still makes some estrogen in tissues other than the ovaries, and aromatase is an enzyme that is required for this estrogen production. The currently used aromatase inhibitors are anastrozole, letrozole and exemestane.

Some women take tamoxifen for two to five years and then switch to an aromatase inhibitor (AI). Many studies have looked at this strategy, and the data clearly show that treatment with an AI after tamoxifen decreases the risk of breast cancer relapse. However, the optimal duration of AI therapy remains unclear. Aromatase inhibitors can also be used as stand-alone hormonal therapy in postmenopausal women. However, optimal duration of treatment with an AI alone is also unclear.

The approach of many oncologists is to make a recommendation based in part upon the patient’s risk of relapse. For a very low risk patient, the risks and side effects of extending treatment beyond five years may be difficult to justify, but in a patient with a very high risk of recurrence, the risk/benefit ratio probably favors continuing therapy for up to ten years, and perhaps even fifteen. There is a test which can be performed on the original tumor specimen to estimate the patient’s risk of a late relapse (i.e., after five years). All of the available information about the characteristics of the patient’s tumor, and knowledge of her other health issues, if any, need to be taken into consideration by the patient and her physician so that they can make a well informed joint decision about the best course of action in treating her cancer.

FDA approves pertuzumab for treatment after surgery in HER2+ breast cancer.

  • While surgery is a fundamental part of treating early stage breast cancer, HER2+ breast cancers are additionally treated with a combination of chemotherapy and targeted agents.
  • Targeted agents like trastuzumab and pertuzumab are antibodies that recognize the HER2 protein on cancer cells and help lead to cell destruction.
  • For many years the standard of care was chemotherapy with trastuzumab followed by trastuzumab alone to complete a year of therapy.
  • Due to data presented in the APHINITY trial, pertuzumab has now been approved for treatment after surgery in operable breast cancer in combination with chemotherapy and trastuzumab, and continued with trastuzumab to complete a year of treatment.
  • Patients treated with both trastuzumab and pertuzumab lived longer without a relapse of their cancer compared to those patients treated with trastuzumab alone.
  • Based on these results, pertuzumab is now approved for use in high risk, operable, HER2+ breast cancer in conjunction with chemotherapy and trastuzumab to complete a year of treatment.

Breast cancer clinical trials.

Clinical trials are research studies conducted in order to help doctors discover new treatments for breast cancer, as well as new ways to detect, diagnose, and reduce the risk of disease. Clinical trials also help researchers and doctors decide if the side effects of a new treatment are acceptable when weighed against the benefits offered by the new treatment.

Clinical trials are just one type of research that's done before a new treatment becomes available to people. New medicines must first be discovered and tested in preclinical trials before researchers even think about clinical trials. According to the American Cancer Society, about 1,000 potential medicines are tested before one makes it to clinical trials. On average, a new medicine to treat breast cancer has been studied for at least 6 years (and sometimes many more) before a clinical trial on it is started.

Researchers don't know what the results of clinical trials will be. This uncertainty can make it hard to decide if you want to participate in one. In rare cases, clinical trial volunteers have been hurt by the treatment or procedure being tested. At the same time, hundreds of thousands of people have been helped and are alive because other people chose to participate in a trial that resulted in a new, more effective treatment. While clinical trials are important, the choice to participate in one is very personal and depends on your unique situation. As with any breast cancer treatment, you and your doctor need to weigh the benefits against the risks and decide what's best for you.

Today, fewer than 5% of breast cancer patients receive treatment for their disease in a clinical trial. Why? One factor is that information about current trials and how to enroll in a trial are often not well understood. In the U.S., the National Cancer Institute provides information on clinical trials - visit www.cancer.gov or call 1-800-4CANCER for more information on nationally available clinical trials. For more information about clinical trials currently available through Huntington Cancer Center, visit www.huntingtonforher.org or call the Clinical Research Department directly at (626) 397-3877. Remember to always talk to your doctor. He or she may know of a trial that is right for your unique situation.

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