1995 Volume 8 Issue 2 Pages 145-150
The National Toxicology Program (NTP) has established a “qualitative” quality assurance (QA) pathology program in order to accurately generate pathology data in 90-day toxicity and 2-year carcinogenicity studies in rats and mice.
The NTP studies are conducted in several contract laboratory facilities in the United States. The study pathologist completes a histopathologic examination and submits a draft pathology report to the NTP. The pathology narrative and summary tables are evaluated to indentify target and semi-target organs and histopathologic lesions to be microscopically reviewed.
The NTP “qualitative” QA pathology procedures consist of three stages of reviews for histopathologic diagnoses, involving two independent pathologists and a panel of pathologists on a Pathology Working Group (PWG). First, the QA pathologist microscopically reviews the diagnoses for the following organs and lesions: (1) all tissues of target organs, (2) all of especially selected neoplastic or non-neoplastic lesions of semi-target organs, (3) all neoplasms diagnosed in the study, and (4) all tissues from 10% of animals in the control and high dose groups. In addition, the histotechnique quality, tissue accountability, slide identification, and untrimmed gross lesions are evaluated. Second, a chairperson of PWG slide review meeting also reexamines all of the aforementioned organs and lesions reviewed by the QA pathologist. Third, six to eight PWG pathologists primarily review the representative slides with compound-related lesions and histopathologic diagnostic discrepancies between the study and QA pathologists. When the PWG disagrees with the study pathologist, the PWG recommends the stud pathologist to reexamine the lesions in question. When the study pathologist agrees to the PWG's opinions, he corrects his original diagnoses and generates the final pathology report.
