HMN 2026: How Updated guidelines standardize how tumor response is measured after surgery

Researchers at the Johns Hopkins Kimmel Cancer Center and its Bloomberg~Kimmel Institute for Cancer Immunotherapy have released updated consensus guidelines and an associated reproducibility study to standardize how pathologists assess tumor response to neoadjuvant therapy (administered prior to surgery) across a dozen solid tumor types.

The recommendations, published in Annals of Oncology, provide the first unified, pan-tumor framework for evaluating residual viable tumor (RVT, the amount of cancer cells remaining), necrosis (cancer cell death) and regression (a constellation of histologic findings that includes inflammation and features of wound healing) after presurgical treatment. They refine and expand earlier immune-related criteria first proposed in lung cancer in 2018, and in a pan-tumor fashion in 2020, which are now updated based on five years of real-world use, questions from the field and new reproducibility data.

A related reproducibility study, published in Annals of Oncology, found that the tumor guidelines can be applied across many different tumor types and achieve consistent results when used by different pathologists around the world.

“Neoadjuvant therapy is rapidly expanding across cancer types, and pathologic response is emerging as a predictor of long-term survival and an important clinical trial endpoint,” says lead author Julie Stein Deutsch, M.D., assistant professor of dermatology, pathology and oncology.

“However, scoring systems have varied widely by tumor type, making it difficult to compare across studies or apply results reliably in practice. This unified approach establishes a common language that will benefit clinical care, research and future regulatory use.”

The updated framework was prompted by growing evidence that tissue changes seen under a microscope that indicate a cancer is shrinking or responding to treatment—particularly after immunotherapy—appear remarkably consistent across cancers. The research team previously reviewed about 500 specimens treated with anti-PD-1 immunotherapy drugs alone or in combination with other agents (such as chemotherapy or targeted therapy) and observed similar patterns of response regardless of tumor origin. John Hopkins Kimmel Cancer Center investigators worked with SITC and INMC to create a single, harmonized standard, recognizing that parallel systems risked confusion and limited comparability.

“Most pathologists around the world are generalists, not tumor-type specialists,” says senior author Janis Taube, M.D., director of dermatopathology and co-director of the Bloomberg~Kimmel Institute tumor microenvironment laboratory. “Switching between multiple scoring systems is inefficient and can lead to inconsistent reporting. Our findings support a pan-tumor system—and importantly, no existing tumor-specific system outperforms this unified approach in predicting patient outcomes.”

A major advance with the new guidelines is their demonstrated reproducibility, the researchers say. In a multi-institutional, international study involving 14 pathologists, RVT scoring using the updated criteria proved highly reproducible after a short, standardized training session. Using the standardized criteria, pathologists demonstrated high concordance in scoring RVT, regression and necrosis, regardless of tumor type, anatomic location or whether the specimen was a surgical resection or biopsy.

The findings were presented at the American Society of Clinical Oncology annual meeting in 2024. These findings reinforce the rationale for a unified, pan-tumor approach to pathologic response assessment comparable to Response Evaluation Criteria in Solid Tumors (RECIST), the standard method doctors use to measure how tumors change in size on imaging scans, and provide a validated foundation for standardized data collection as neoadjuvant (therapy given before surgery) and perioperative (therapy given before and after surgery) approaches continue to expand across cancer types, the researchers say.

“Reproducibility is essential,” says Deutsch. “Different pathologists must arrive at similar scores if these metrics are going to guide patient care and clinical trials. Our training materials make that possible, and we are partnering with SITC to disseminate these resources.”

The researchers say next steps include refining clinically meaningful RVT thresholds for specific tumor types as additional survival data become available.

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