Adjuvant Therapy for Stage II and III Colon Cancer
Panelists: John Marshall, MD, Georgetown University; Cathy Eng, MD, Vanderbilt University; Tanios Bekaii-Saab, MD, Mayo Clinic; Dustin Deming, MD, University of Wisconsin; Michael Morse, MD, Duke Cancer Institute
John Marshall, MD: Outcomes for patients with advanced colorectal cancer have improved drastically, particularly for patients receiving multiple lines of therapy. As we develop a deeper understanding of disease biology, our ability to personalize therapy throughout the disease course continues to improve. In this OncLive Peer Exchange® discussion “Personalized Strategies for Advanced Colorectal Cancers,” I am joined by an amazing panel of experts in GI [gastrointestinal] medical oncology. Today we are going to look at abstracts from the ASCO [American Society of Clinical Oncology] 2019 meeting and will discuss how these new findings will impact individualized patient care.
I am Dr John Marshall, chief of the Division of Hematology/Oncology at MedStar Georgetown University Hospital and professor of medicine and oncology at Lombardi Comprehensive Cancer Center at Georgetown University in Washington, DC. Participating today are our distinguished panel, and what a distinguished panel we’ve got. Dr Cathy Eng, professor of medicine and co-director GI oncology at the Vanderbilt-Ingram Cancer Center in Nashville, Tennessee. Cathy, welcome.
Cathy Eng, MD: Thank you.
John Marshall, MD: Dr Tanios Bekaii-Saab—Tony—professor, Mayo Clinic College of Medicine and Science and consultant at the Mayo Clinic in Arizona. Tony, welcome.
Tanios Bekaii-Saab, MD: Thank you.
John Marshall, MD: Dr Dustin Deming, associate professor at the University of Wisconsin’s Carbone Cancer Center in Madison, Wisconsin. Welcome.
Dustin Deming, MD: Thank you.
John Marshall, MD: Last but not least, my good friend Dr Michael Morse, professor of medicine and GI medical oncologist at the Duke Cancer Institute in Durham, North Carolina. Michael, welcome.
Michael Morse, MD: Thank you, John.
John Marshall, MD: Thanks, everybody, for taking time to join us today to really dive into the newest stuff that’s going on in colorectal cancer. Dustin, I’m going to pick on you first. We’re going to talk a bunch about new innovations in adjuvant therapy. Some new data were presented here. Before we dive into that, I want you to set our current standards for early stage, stage II and III, colon cancer. Fire away.
Dustin Deming, MD: When we’re thinking about adjuvant therapy for stage II and stage III colon cancer, we’re looking at what the risk is for this patient first. First for stage III, the node positivity is really what drives the risk for that particular patient population.
John Marshall, MD: Once you have positive nodes, and I know I’m just jumping right in, do you then not care about the other stuff or is it once you’re in nodes, you’re in nodes?
Dustin Deming, MD: To some extent, you still care, but largely, the nodes are really what’s going to drive the risk and really want you to go for adjuvant chemotherapy, to some extent.
John Marshall, MD: Fair enough. Does node count matter?
Dustin Deming, MD: Node count does matter. When we’re thinking about higher-risk and low-risk stage III, the node positivity, whether we’re talking N1 or N2 disease, really matters.
John Marshall, MD: Drill down on that a little bit. What do you mean by that?
Dustin Deming, MD: Those patients who have just a few nodes, less than 4 nodes, we would typically think of as a lower-risk patient. Those with greater than that, we would think of particularly as a potentially high-risk population.
John Marshall, MD: Mike, what’s our denominator here? How obsessed are we about the denominator of nodes still?
Michael Morse, MD: Obviously there are a number of factors that go into the number of nodes retrieved, and obviously there’s a minimal number we’re in at stage II, but even in stage III, the number of negative nodes is very important in terms of outcomes.
John Marshall, MD: I’ve always debated that. Is it the surgeon’s fault, the pathologist’s fault, or the patient’s fault?
Michael Morse, MD: It’s biology. Clearly, we’re in an era now when pathologists know to look for nodes. Now, whether people choose to go beyond the required number—12, 13, 14—depending on which study you follow, is debatable. Clearly, there is a biologic story going on when there’s a large number of negative nodes that are retrieved.
John Marshall, MD: Yes. Dustin, I’m assuming all our stage III patients are still candidates for chemotherapy, and we’ll get into that a little bit. How do you assess for stage II? What are your key things you look at there?
Dustin Deming, MD: Stage II, is actually, in my opinion, a very personal decision. There are a lot of things that go into determining whether we should think about chemotherapy for patients.
John Marshall, MD: What are some of those things that bundle into that?
Dustin Deming, MD: Purely from a risk standpoint, we think about T4 lesions. We think about perforation, obstruction, and poor differentiation as potential markers of risk. There are also some data about those patients who don’t have their 12 or 13 lymph nodes evaluated as a potentially higher-risk population, as well.
John Marshall, MD: Cathy, I struggle with this high-risk group, because we know they have a worse prognosis, and in some cases, worse than some stage III patients. Our data are not really consistent here about adjuvant therapy in stage II helping all that much. What’s your thought on that?
Cathy Eng, MD: It’s still a personal decision between you and the patient, and it does require discussion. A large amount of the data, historically, did not demonstrate a significant benefit for stage II, but then we identified what we considered high-risk based upon the data from the MOSAIC trial. Then from this year’s ASCO, we’re also looking at that once again, although it still remains a bit unclear.