While the use of neoadjuvant therapy, used to shrink or weaken a tumor, is expanding across cancer types, and pathologic response is emerging as a predictor of long-term survival for patients and an important clinical trial endpoint, scoring systems have varied widely by tumor type.

“This makes it difficult to compare across studies or apply results reliably in practice,” notes Johns Hopkins’ Julie Stein Deutsch, assistant professor of dermatology, pathology and oncology.

She is part of a team from Johns Hopkins Kimmel Cancer Center and its Bloomberg~ Kimmel Institute for Cancer Immunotherapy that recently released updated consensus guidelines and an associated reproducibility study to standardize how pathologists assess tumor response to neoadjuvant therapy across a dozen solid tumor types. Both reports were published in Annals of Oncology.

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.

John Hopkins investigators worked with the Society for Immunotherapy of Cancer (SITC) and the International Neoadjuvant Melanoma Consortium (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, director of dermatopathology. “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 (residual viable tumor) scoring using the updated criteria proved highly reproducible after a short, standardized training session.

“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.”