Christopher Flowers, MD, MS, FASCO, is Chair of the Department of Lymphoma/Myeloma at The University of Texas MD Anderson Cancer Center and was appointed Division Head ad interim of Cancer Medicine in August 2020. He is the 2022 Cancer.Net Associate Editor for Lymphoma. Vicki Keedy, MD, is an Associate Professor of Medicine in the Division of Hematology/Oncology at the Vanderbilt University Medical Center. She is the 2022 Cancer.Net Associate Editor for Sarcoma. Daniel Mulrooney, MD, MS, is an Associate Member in the Division of Cancer Survivorship at St. Jude Children’s Research Hospital. He is the 2022 Cancer.Net Associate Editor for Pediatric Cancers. Sumanta (Monty) Pal, MD, FASCO, is the co-director of City of Hope's Kidney Cancer Program and is the head of the kidney and bladder cancer disease team at the institution. He is the 2022 Cancer.Net Associate Editor for Genitourinary Cancers. Disclosure information for the authors can be found in their individual biographies linked to above.
Doctors and scientists conduct research studies to find better ways to prevent, diagnose, and treat cancer. When searching for cancer information online, you may come across articles about research studies. However, it can sometimes be difficult to tell whether articles you find online are reliable or potential misinformation. One important way to tell if an article you find online is dependable is if it is “peer reviewed.” Here, we break down what to know about peer-reviewed information and the types of peer-reviewed cancer research you may find when searching online.
What are peer-reviewed articles?
For articles published in scientific journals, “peer reviewed" means that the article has undergone a process in which qualified experts have reviewed it, provided feedback, and the authors have responded to that feedback to improve the scientific quality and integrity of the article.
Articles that have not been peer reviewed have not been reviewed by experts in the field for scientific validity or quality. For example, research studies that are published in non-peer-reviewed journals are not heavily scrutinized and have not been reviewed for the quality of the methods performed in the study or for the integrity of the data reported from the study.
One example of a non-peer-reviewed article is called a “pre-print.” Pre-prints are rapid reports of study results that are often found in the online version of a journal that is published before peer review is performed. Pre-prints allow for rapid distribution of important information. However, the final article for the study may change significantly after it goes through peer review. Other non-peer-reviewed sources can include book chapters, blogs, or medical articles in a magazine.
If you come across an article online that you’re not sure has been peer reviewed, bring it up with your health care team. They can point you toward sources of peer-reviewed research and other cancer information that is helpful and dependable. Learn more about evaluating cancer information online.
“‘Peer reviewed’ means that the article has undergone a process in which qualified experts have reviewed it, provided feedback, and the authors have responded to that feedback to improve the scientific quality and integrity of the article.” – Sumanta (Monty) Pal, MD, FASCO, co-director of City of Hope's Kidney Cancer Program, head of the kidney and bladder cancer disease team at the institution, and the 2022 Cancer.Net Associate Editor for Genitourinary Cancers
What is peer-reviewed cancer research, and why is it important?
Peer-reviewed cancer research studies are evaluated and critiqued by an independent group of scientific experts in the same field before that research is performed. The purpose of this review is to ensure the scientific merit of the study by asking if the research question being studied is important and based on sound science. Peer review also ensures that the methods used to answer the research question are safe and appropriate. Often, research proposals must go through a rigorous peer review before they receive funding from research organizations.
However, not all research studies go through a peer review prior to the research being performed, particularly if it is not required for the funding of the project. These often are smaller pilot projects or projects that are privately funded. There is a risk that non-peer-reviewed studies may not use reliable research techniques and may not hold as much scientific value, because they do not undergo a formal critique. It is important when evaluating studies to identify whether they are peer reviewed, as peer review is crucial to ensuring scientific integrity. If you are unsure whether a study you have found is peer reviewed, your health care team can help you answer this question.
“Peer review also ensures that the methods used to answer the research question are safe and appropriate. Often, research proposals must go through a rigorous peer review before they receive funding from research organizations.” – Vicki Keedy, MD, Associate Professor of Medicine in the Division of Hematology/Oncology at the Vanderbilt University Medical Center and the 2022 Cancer.Net Associate Editor for Sarcoma
What does "levels of evidence" mean in cancer research?
Cancer research studies are assigned a level of evidence based on how strong the evidence is in a particular study. It is simplest to think about levels of evidence in cancer research like a school report card, with “A” being the highest level of evidence. When the level of evidence is “A,” that means we have the best information to provide clarity about what the right way is to diagnose or treat a given type of cancer.
The other important feature to understand when considering levels of evidence is the experimental design of the study. The best type of experimental design for testing whether one diagnostic or treatment option is better than another is a called a randomized controlled trial. In a randomized controlled trial, participants in the trial are randomly assigned to receive a particular intervention, such as Treatment 1 versus Treatment 2, based on the belief that we do not know which treatment is more likely to benefit patients in general. High-quality randomized controlled trials provide an A-grade level of evidence.
When multiple randomized controlled trials have been done to answer the same research question, then researchers may perform something called a “systematic review” of these trials to combine and provide a summary of all the evidence from the multiple trials. The summary from a systematic review highlights the best available research on a specific topic and can be a way to improve grade A evidence.
“It is simplest to think about levels of evidence in cancer research like a school report card, with “A” being the highest level of evidence. When the level of evidence is “A,” that means we have the best information to provide clarity about what the right way is to diagnose or treat a given type of cancer.” – Christopher Flowers, MD, MS, FASCO, Chair of the Department of Lymphoma/Myeloma at The University of Texas MD Anderson Cancer Center and the 2022 Cancer.Net Associate Editor for Lymphoma
Other forms of studies have lower levels of evidence, including cohort studies, which are when researchers study the event as it occurs, and case-control studies, which is when we know what outcome has occurred for 2 different groups of people and compare the results. Both types of studies would be considered different forms of “grade B” evidence. When we do not have data to provide information on a particular research question, we rely on expert opinion, which would also be a lower level of evidence.
What are the differences between research studies in cell lines, animals, and humans?
Cancer research can be performed on several different sources, including cell lines, animals, or humans. The choice often depends on the research question being asked and available resources.
In cell line studies, the cells can be isolated from animals or humans and preserved or grown in culture dishes. These cells may come from different tissue, such as the bone, brain, or muscle of animals or humans. Laboratories can change these cells to grow indefinitely, which are called “immortalized cell lines.” Immortalized cells provide a long-lasting resource for future studies. Cells can also be changed into induced pluripotent stem cells (iPSCs), which are important to research because under the correct conditions, they can grow into nearly any cell type.
Animals can also be used as models for studying human disease because there are many biologic and genetic similarities between animals and humans. Mice and rats are the most common animals used in research. However, depending on the disease being studied, different animals may be used, ranging from zebrafish to larger animals. Many animals have a shorter lifespan than humans, which allows diseases like cancer to be studied over an entire lifecycle. Animals are used to test how safe and effective new drugs and medical treatments are, and they can also help identify potential side effects. In fact, new drugs must first be tested in animals before human studies can begin.
While research into new medical treatments often begins in cell lines and animals, studying humans is important to truly understand the effects on the various organ systems in the human body. There is no substitute for the complexity of human behavior and the interactions new treatments can have within our bodies. Studies conducted in humans are watched very closely for safety and may identify new risks and benefits that have not yet been shown in other studies.
How are research studies in humans conducted?
Medical treatments studied in humans, including those for cancer, are called “clinical trials” and are conducted in 4 phases. A phase I clinical trial is designed to test the safety of a new drug or procedure and identify potential side effects. A phase II clinical trial is focused on determining if the drug or procedure is effective. Phase III clinical trials are conducted in large populations and test the treatment compared to other treatments or the standard of care, which is the best treatment currently known. Phase III clinical trials are required for a drug or procedure to be approved by the U.S. Food and Drug Administration (FDA) for regular use. Finally, phase IV clinical trials are conducted after the FDA has approved a new treatment and are used to monitor that treatment over a longer period of time and in diverse populations. Learn more about patient safety in clinical trials.
“While research into new medical treatments often begins in cell lines and animals, studying humans is important to truly understand the effects on the various organ systems in the human body. There is no substitute for the complexity of human behavior and the interactions new treatments can have within our bodies.” – Daniel Mulrooney, MD, MS, Associate Member in the Division of Cancer Survivorship at St. Jude Children’s Research Hospital and the 2022 Cancer.Net Associate Editor for Pediatric Cancers
Research studies are an important way for doctors to identify new ways to care for and treat people with cancer, and peer review is an important tool for ensuring that research is safe and reliable. Talk with your doctor if you have any questions about finding trustworthy cancer research studies or other cancer information online.