Personalized Cancer Treatment
Defining a Personalized Approach to Cancer Treatment
Cancer was diagnosed in about 1.5 million people in the United States in 2010. Despite this large number of people, the cancer experience varies from person to person. Advances in screening and earlier detection in some cancers have allowed more people to live longer overall and to live longer without progression of cancer. Advances in treatment have also led to increased survival rates, especially for people with more advanced disease. Still, not every treatment is effective for every person. Why?
In an attempt to answer that question, researchers have been studying hundreds of thousands of samples from various types of tumors, and they have discovered that tumors differ in very important ways, even when they’re from the same body site, such as the breast, colon, or lung. As researchers and doctors begin to better understand the biology of cancerous tumors, they can develop new treatment options and offer personalized therapy based on the unique features of a tumor.
Treatment for most types of cancer was once chosen only according to the stage of disease (the size of the tumor and whether cancer had spread to nearby lymph nodes or other organs) and its histologic classification (or how the tissue cells that make up the cancer looked when examined with a microscope). Stage and histologic type remain important, but the discovery of tumor markers (biomarkers) and the development of technology to identify biomarkers in tissues have led to an added layer of classification for some cancers — one based on molecular subtypes.
As you will learn in this content, biomarkers form the basis of personalized cancer treatment, or treatment matched to the specific features of a tumor in a given person. Personalized treatment also includes approaches to preventing or decreasing the risk of cancer according to the results of genetic testing. Personalized treatment holds the key to more effective treatment and control of cancer.
Genes play an important role in cancer, and in “The Role of Genes in Cancer,” you will learn how genetic mutations (abnormalities) can lead to the development of cancer or to a hereditary predisposition (tendency) for some cancers (see The Roles of Genes). Genetic counseling and testing provide the chance for a person with a suspected genetic predisposition for a specific cancer type (for example, breast cancer) to better understand his or her risk for cancer and work with doctors to create a personalized approach to preventing or decreasing the risk of cancer based on his or her unique genomic profile.
In addition, biomarkers and tumor testing have improved cancer care by providing information that helps physicians match the right person with the right treatment plan, biomarkers can serve a variety of other functions, such as helping to predict recurrence or prognosis (estimate of the outcome) and monitoring response to treatment. All of these benefits help to create a personalized treatment plan. In addition, advanced testing methods are now available to analyze blood, tumor specimens, and other tissue to look for abnormalities in genes that cause some cancers to develop or metastasize (spread beyond the original site). With these methods, researchers are adding to the usefulness of biomarkers by discovering genetic mutations in some tumors that can help guide treatment decisions. You can learn about biomarkers in the Importance of Biomarkers.
Treatment decisions have been traditionally made on the basis of the report from the pathologist, a doctor who specializes in the microscopic examination of tissues for cancer (and other diseases). As researchers discover more about the biology of different types of cancer, the information included on the pathology report is becoming more complex. “Your Pathology Report” can help you learn more about what the report means, which can help you better understand what your treatment options are.
The core of this content describes how biomarkers and targeted therapy — a new approach to cancer treatment — work together to personalize the management of several major types of cancer, primarily breast, colorectal, and non-small cell lung cancer. Because it is not possible to address every aspect of these topics, additional web site sources will be listed in each section where you can find more details to help you better understand the personalized treatment of cancer.
People with newly diagnosed cancer are often fearful because they remember ordeals that family or friends went through with cancer. But research advances have changed the cancer experience in many important ways. What doctors know today about cancer is worlds away from what they knew in your grandmother’s day.
1. THEN...All tumors were thought to be the same.
NOW...Tumors are known to be very different from each other.
Researchers once thought that all tumors from a particular site (for example, the breast) were the same. Now, advances in technology and the results of the Human Genome Project have enabled researchers to identify the molecular features of a tumor, and they have found that the molecular, or genetic, profile can vary greatly, even among tumors from the same site. For example, instead of breast cancer being one type of cancer, it is now five different subtypes, depending on its genetic profile. The discovery of different subtypes helps to explain why a treatment works for one person but not another.
2. THEN...The approach to treatment was “one size fits all.”
NOW...More options are available for controlling cancer.
Strong chemotherapy drugs, surgery, and radiation therapy were once the only treatment options for cancer. Although these treatments are still used, doctors now know that some cancers respond better to some drugs than others and that “less is better” often applies to surgical and radiation therapy. For example, removal of just the breast tumor with some nearby tissue (known as lumpectomy) has been found to be as effective as removal of the entire breast for many women, new techniques allow radiation to be delivered more precisely, and adjuvant therapy (treatment given after primary therapy) may not be needed by everyone to avoid recurrence. In addition, a new treatment approach — targeted therapy — allows for more focused treatment in some cancers, helping to cause less damage to healthy cells. Lastly, substantial advances in medications to relieve the side effects of treatment make it possible to keep people more comfortable during treatment.
3. THEN...Doctors called all the shots when making treatment decisions.
NOW...People with cancer are encouraged to be part of the decision-making process.
Because treatment choices were once limited, doctors alone decided which treatment was best. With more treatment options now available, doctors today ask their patients to be an active participant in making treatment decisions. People with cancer should learn all they can about their particular tumor so that they can work with their doctors to choose a treatment plan that is best for an individual based on his or her preferences as well as the doctor’s knowledge of optimal treatment.
4. THEN...Doctors and their patients merely hoped that treatment would keep cancer from recurring.
NOW...Tests are available to help doctors predict if cancer will recur or respond to treatment.
Doctors once chose treatment based on what worked well for other patients with the same type of cancer. However, doctors had few or no ways to know how likely it was that cancer would recur (come back) after treatment. The discovery of biomarkers and the development of methods to test for the presence of biomarkers have helped doctors predict the likelihood of recurrence and response to treatment. Biomarker testing is helping people with cancer avoid treatment that is not likely to be effective. This testing also helps people with a high risk of recurrence receive more aggressive treatment to increase the likelihood of a good outcome.
5. THEN...Cancer was a death sentence.
NOW...Many cancers are treated as chronic diseases.
A diagnosis of cancer once created great fear of imminent death, with few options for cure. Earlier diagnosis and improvements in treatments for several different types of cancer have led to many people living longer, either with no evidence of cancer or with cancer that is controlled (not progressing). The American Cancer Society estimates that since the early 1990s, nearly three- quarters of a million cancer-related deaths have been prevented. In addition, the number of cancer survivors has grown steadily over the past 40 years, from 3 million in 1971 to about 10 million in 2001 to nearly 12 million in 2007.
Learn all you can about your cancer and its treatment so that you can work with your doctor to select a treatment that is right for you.