Cancer screening recommendations are well-established for breast, cervix, colorectal, and prostate cancers-as well as for lung cancer in smokers who are known to be at high risk. But for other cancers collectively responsible for the majority of cancer deaths, early detection tests are lacking. This point is made in a recent editorial in the journal Cancer by Karen Glanz, PhD, MPH, the George A. Weiss University Professor at the Perelman School of Medicine and School of Nursing at University of Pennsylvania, and her colleagues (2022; https://doi.org/10.1002/cncr.34395). The editorial is a response to new research from another group of oncologists who set out to identify key risk factors for any type of cancer and specific populations that may be at risk to better inform the development of multi-cancer early detection tests (Cancer 2022; https://doi.org/10.1002/cncr.34396).
To do this work, the researchers (led by Alpa V. Patel, PhD, Senior Vice President of Population Science at the American Cancer Society) analyzed data from two large American Cancer Society prospective cohort studies: the Cancer Prevention Study II Nutrition Cohort and the Cancer Prevention Study-3. Collectively, those datasets included nearly 500,000 people and 15,226 invasive cancers were diagnosed among participants within a 5-year time period. The data showed the following information. 1) Nearly all people over age 50 had an absolute risk of greater than 2 percent of being diagnosed with cancer within 5 years. 2) Older age and smoking are the two most important risk factors associated with the risk of developing any cancer within 5 years. Glanz and her colleagues explained in their editorial that there's a lot more work that needs to be done before multi-cancer early detection tests-that truly improve outcomes and improve health-can be developed, starting with demonstrating the practical utility of describing cancer as a single endpoint. In an interview with Oncology Times, Glanz shared her viewpoints from the editorial.
1 What is problematic about looking at cancer as a single endpoint when it comes to screening, cancer risk, and prevention? What is helpful about looking at it this way?
"Cancer is many diseases, not one. The many diseases share a common main feature-they are characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue. Treating cancer as a single endpoint ignores the huge variety across different types of cancer-who gets them, risk factors for each cancer, what is the average survival or mortality, and so on. As far as risk, smoking is a major contributor to the risk of certain cancers (lung cancer, head and neck cancers), but not as much for others. Some cancers are highly treatable and have more than 90 percent 5-year survival rates (e.g., thyroid cancer), while others have much lower survival rates (e.g., liver and pancreatic cancer).
"The authors of the article that our editorial discusses (Patel, et al) propose that it's helpful to look at risk of cancer as a single endpoint. We don't know of any research that has asked whether either clinicians or patients would agree with that point, but it would be an interesting question to study."
2 Could the findings from the research be used to develop a multi-cancer early detection test?
"As we've noted in our editorial, we feel there is a need for more definitive data about the benefits of an multi-cancer early detection test screening approach in order for it to be widely used, reimbursed by insurance payers, and recommended by expert guideline committees. Aside from uncertainties about the benefits, there are practical concerns.
For example: 1) What diagnostic tests should be done if the findings form multi-cancer early detection tests suggest that a person may be at high risk for one or more types of cancers? 2) What clinical recommendations should be made based on the multi-cancer early detection test findings and further diagnostic tests? 3) Is there a possibility that multi-cancer early detection tests will 'miss' some early cancers? From the patient perspective, the idea of a non-invasive test-based on a blood sample instead of something that 'goes inside your body' like a colonoscopy or Pap test-may be appealing in its own right, whether or not it has a positive health impact.
"We used the term provocative [about the Patel, et al, paper] because it proposes that the research may support taking further steps, such as in the development, testing, and use of multi-cancer early detection tests. It is not definitive, because research hasn't yet demonstrated that the multi-cancer detection tests can lead to better health or cancer outcomes (such as showing earlier detection leading to longer survival and/or better quality of life)."
3 What's the most important thing to know about multi-cancer early detection tests?
"This research uses available data to examine the 'potential' for treating cancer risk as a single endpoint. The findings don't provide a strong conclusion that this approach is 'ready for prime time' use in cancer care-and they were not intended to tackle that specific question. The takeaway from our editorial is for oncologists and physicians to consider the limits of current knowledge if they are considering ordering these tests or are asked about them by their patients-understanding the uncertainties.