Mandatory second opinion pathology slide review for new referrals is a common practice.
We conducted a retrospective cohort study to investigate the discordance rate.
Of 667 new head and neck cancer referrals cases over 5 years, 22% were discordant.
Histology but not biopsy site were associated with discordance on multivariate models.
Routine slide review may reveal information that alters the treatment course.