Importance of Identifying HER2 Status in Metastatic Colorectal Cancer


Following its discussion on trastuzumab deruxtecan and tucatinib therapy in HER2+ mCRC, the panel emphasizes the importance HER2 status identification in metastatic colorectal cancer.


Kanwal P. Raghav, MD: I agree with all the statements that have been made. But at some point we need to optimize what we’re doing in GI [gastrointestinal] oncology. This isn’t unprecedented. We should learn from our breast cancer colleagues. In today’s world, it would be malpractice to report breast cancer pathology without ER [estrogen receptor], PR [progesterone receptor], and HER2 [human epidermal growth factor receptor 2]. HER2 IHC [immunohistochemistry] is a fairly cheap, readily available test in any pathology lab, just like MSI [microsatellite instability testing]. NGS [next-generation sequencing] is a complicated thing. Whether you can get it done depends on how much tissue you have, and the cost criteria are prohibitive. But as we’ve already shown, these are 2 different, very effective therapy options. Both are well tolerated, allowing patients to live for a long period of time. If we can’t rally the troops to do that testing—there’s more emphasis on other NTRK fusions, which are rarely seen. Testing can become a standard of care. Lung cancer is another example. What lung cancer physician would treat a patient, who they’re seeing for the first time, without getting EGFR testing? They won’t, regardless of the burden of disease. Because if it’s an EGFR-driven tumor, chemotherapy is harmful.

Kristen K. Ciombor, MD: Yes, and immunotherapy up front too.

Joel R. Hecht, MD: The difference and the problem with breast cancer is that knowing whether a patient is HER2-positive makes a difference in the adjuvant setting. Remember, about a third of our patients end up having metastatic disease. You’re testing HER2 in a lot of people who will never have metastatic disease. That becomes a payment issue. We need to get payers to do it because it’s easier and better for patients to do this up front. If the patient is cured, that’s great; they never need it. That would be fine. But that’s the difference with breast cancer: for newly diagnosed patients, you want to know their HER2 status up front. Hopefully that patient is cured, but it changes how you treat that patient.

Kanwal P. Raghav, MD: But a large group of patients are diagnosed with de novo metastatic disease. In colorectal cancer, we’re slowly and steadily reaching a stage with enough biomarker therapies. We’re trying to move those biomarker therapies into first-line setting. We need to finish our homework with regard to how we’re going to test these patients.

Pashtoon M. Kasi, MD: To that point, it’s not just the cost; it’s also the workflow. Colorectal cancer is a common malignancy. Seventy percent of folks who don’t need HER2 testing reflexively may not be ideal. But we’re looking at the workflow within our institution too. If pathologists are getting a liver biopsy sample or a lung, that’s a metastatic sample. If they’re getting a surgical sample, they’re the first individuals to know if it’s stage II or III. They can grossly filter out a lot of nonmetastatic samples so they don’t have to reflexively test them.

Joel R. Hecht, MD: This is also when we need to have our pathology colleagues involved.

Pashtoon M. Kasi, MD: Exactly.

Joel R. Hecht, MD: Regardless of whether it’s CAP or 1 of the other organizations, because I don’t know your practice pattern. For the majority of patients I see, their original tissue was done someplace else, often in a surgery center. Where does the gastroenterologist in someone’s surgery center send off? There are more national groups doing this, and that’s why we need the national organizations. We were talking about breast cancer, in close collaboration between oncology and pathology. This may be a place to expand that.

Transcript edited for clarity.

Related Videos
Video 18 - "Reflecting on Differentiated Thyroid Cancer: Final Insights"
Video 17 - "Phase 2 ATLEP Trial Results"
Pashtoon Murtaza Kasi, MD, MS
Debu Tripathy, MD
A panel of 5 experts on lung cancer
A panel of 5 experts on lung cancer
Katrina S. Pedersen, MD, MS, associate professor, John T. Milliken Department of Medicine, Division of Oncology, Medical Oncology program leader, cofounder, Young Onset Colorectal Cancer Program, Washington University School of Medicine in St. Louis, Siteman Cancer Center
Debu Tripathy, MD
Parul N Barry, MD,
Ramez Kouzy, MD, MD Anderson