Introduction/Background Serous tubal intraepithelial carcinoma (STIC) is known to be a putative precursor for the most common and aggressive ovarian carcinomas, namely ovarian high-grade serous carcinoma. Precise and early diagnose this disease is therefore one of the priorities for tissue diagnosis in gynecologic oncology. At the same time routinely applied algorithm for STIC diagnosis could not cover some grey zones in its diagnostics.

Methodology The study included 70 patients (125 fallopian tubes), all of the specimens were investigated morphologically and immunohistochemically (p53, Ki-67, p16, stathmin1 and laminingamma1). Statistics involved exact Fisher’s test, χ²-test, Cohen’s kappa

Results Expression of p16, stathmin1 and laminin-gamma1 was revealed in 85%, 77,5% and 90% of STIC consequently. In 4 tubes with STIC, only one of these tree markers was positive but we has no cases with all three negative expression. In STIC cases, expression of p16, stathmin1 and laminin-gamma1 was high both in the presence and in the absence of p53 expression in atypical cells. In most cases, positive expression of at least two of the three studied markers was shown. p16, stathmin1 and laminin-gamma1expressin does not differ between p53positive and p53-negative STICs. Cohen’s kappa for STICs with ambiguous p53 expression was moderate (0.55) when we used only p53 and ki-67 expression. P16/laminingamma1/stathmin1 diagnostic panel let us increased Cohen’s kappa to good reproducibility (0.72), (p<0.05).

Conclusion Lack of grey zones in STIC diagnostics and good reproducibility of diagnoses allows us to recommend p16, stathmin1 and laminin-gamma1 diagnostic panel for STIC diagnostics, especially in case of ambiguous p53 expression and/or borderline KI-67 expression.

Disclosure Nothing to disclose.