Guideline Recommendations for CIN Prophylaxis

Hope S. Rugo, MD, FASCO: It’s really important: the whole concept of why we worry about this and how we treat it and also prophylax. We’ll talk more about that later. Tiffany, there are clear risk factors, as Bill and Rita pointed out. Can you tell us a little more about the risk factors, how you monitor patients, and if the risk factors change either the chemotherapy you choose, the doses, or maybe your use of prophylactic growth factors?

Tiffany A. Traina, MD: There’s a lot there to unpack. There’s a good body of literature that describes certain risk factors in patients who are more prone to develop neutropenia and cytopenias. Older patients, which is defined as 65 years or older; and patients who have some compromised organ function, like elevated bilirubin; or patients who have a low BSA [body surface area] or low body mass index or who have low baseline white blood cells in total are more prone to develop neutropenia. Additionally, patients with more advanced disease and more compromised bone marrow, who have been through multiple lines of therapy, are more likely to experience neutropenia with the subsequent regiment. We see that in breast cancer because we’re fortunate enough to treat patients in the sixth-, seventh-, or eighth-line setting, so clinical practice is where we’ll often see this.

There is even literature around certain SNPs [single nucleotide polymorphisms] that might predispose the neutropenia depending on the regimen being used. It is not actionable, but clearly, there are some predisposing factors. NCCN [National Comprehensive Cancer Network] gives guidance about the use of growth factors, and they divide the regimen by high risk, more than 20% likely to experience neutropenia, there’s a recommendation to use prophylactic growth factor.

There can be intermediate-risk regimens—10% to 20% neutropenia, where they say to consider the use of prophylaxis. But for a low-risk regimen of less than 10% risk of neutropenia, NCCN does not recommend prophylaxing, but that’s primary prophylaxis. Obviously, we’re all very comfortable once you’ve gone to treat a patient on, say, day 1 of a cycle, and they present with limiting neutropenia, then incorporating growth factor in that secondary prophylaxis setting is often preferred to keeping patients on schedule at an appropriate dose and intensity.

Hope S. Rugo, MD, FASCO: Yeah, those are good points, and I like hearing about the NCCN Guidelines. As you know, soon after the start of the pandemic, we put in—I don’t know a pandemic revision for the NCCN growth factor guidelines, which suggested that you might ratchet down a little in terms of when you’d use growth factors to try to avoid hospitalizations or febrile neutropenia and just neutropenia in general. That was really helpful. The NCCN website has the pandemic recommendations, so that’s helpful.

Transcript edited for clarity.