A Pathologist’s Crucial Role in Diagnosing Breast Cancer

David L. Rimm, MD, PhD, goes by an adage that a cancer diagnosis won’t be made until the pathologist says so. As a pathologist himself, he often takes part in multidisciplinary tumor boards, where he will give his expertise into the diagnosis of the patient, including the specific target patterns.

During the 2025 San Antonio Breast Cancer Symposium (SABCS), Rimm moderated a discussion titled “Antibody Drug Conjugates: Are They Targeted Therapy or Chemotherapy?” There, the panelists focused on areas including HER2-low/ultra-low breast cancer from the pathologists’ perspective, antibody drug conjugates (ADCs) as targeted therapy, and evidence that ADCs are chemotherapy.

These discussions further emphasized the point that a pathologist does play a critical role in the management of the disease.

Rimm is the Anthony N. Brady Professor of Pathology and professor of medicine, as well as the director of Yale Cancer Center Tissue Microarray Facility, director of Yale Pathology Tissue Services, and director of the Physician Scientist Training Program, Pathology Research, at Yale University School of Medicine.

Transcript:

In general, in academic centers, certainly, and in many centers, the pathologist plays a role in the tumor board and shows what they’re seeing and helps the clinician understand the patient-specific diagnosis and the patient-specific target expression pattern. That is critical. Most institutions that have tumor boards include a pathologist, and the pathologist plays the key role of making the diagnosis, helping the clinicians understand the extent of the diagnosis and the subtype, and even the subclass in some cases, and then the level of expression on the target. As a pathologist, that part of the therapeutic process shouldn’t be overlooked at all, and is very important, as I often, almost jokingly say, “It’s true that no one has cancer until the pathologist says so.” It requires a tissue diagnosis to make a diagnosis of cancer, and that’s why pathologists must play a critical role in the management of the patient.

Reference

Translational controversies: ADCs, targeted therapy, or chemo? Presented at the 2025 San Antonio Breast Cancer Symposium. San Antonio, TX; December 9-12, 2025.