[1115] Endometrial Clear Cell Carcinomas with and without Aberrant p53 Expression: A Study of 16 Cases

Deborah DeLair, Robert A Soslow. Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Clear cell carcinoma is a relatively rare tumor type which classically does not demonstrate a mutation in TP53 in ovarian examples. Endometrial serous carcinomas (EMSC) nearly always show these mutations, almost all of which correlate with overexpression (OE) of the protein or complete loss of expression (null phenotype) by immunohistochemistry (IHC). Little is known, however, about p53 expression in endometrial tumors with clear cell histology.
Design: Endometrial carcinomas which showed typical clear cell histology (EMCC), diffuse positivity with HNF-1β by IHC, and aberrant p53 expression (OE or null phenotype), also by IHC, were included. Mixed epithelial and morphologically ambiguous tumors were excluded. Clinical characteristics and immunohistochemical results for p16 (OE or not) and ER were also recorded. For comparison, EMCCs without aberrant p53 were also analyzed.
Results: Eight cases each of HNF-β-positive EMCC with and without aberrant p53 expression were identified. The clinical and immunohistochemical results are shown in the tables below.

Tumors with aberrant p53 expression (1 tumor had null phenotype)
Case #p16ERStageAgeOutcome
1--IVb65AWD
2equivocal-IVb61DOD
3OE-IVb71AWD
4--IVb74DOD
5--IVb65DOD
6--IVb78DOD
7equivocalfocal +IVb61AWD
8--IVb67AWD




Tumors without aberrant p53 expression
Case #p16ERStageAgeOutcome
1--IIIc261DOD
2--Ia65NED
3--Ic73NED
4--Ib83DOD
5--Ia51DOD
6--Ia55NED
7--IIIc175AWD
8--IIIc256NED


All patients whose tumors showed aberrant p53 presented at advanced stage due to peritoneal metastases and are either dead of disease (DOD) or alive with disease (AWD) on follow-up. Only 3 of the patients whose tumors lacked aberrant p53 presented at advanced stage and in each case this was due to lymph node metastases, not peritoneal dissemination. Half of the patients without aberrant p53 have no evidence of disease (NED). The average age of patients in both groups was not significantly different.
Conclusions: EMCCs with aberrant p53 expression present in a fashion similar to that of EMSC (peritoneal dissemination) and have poor prognoses. EMCC without aberrant p53 present in a similar manner to endometrioid adenocarcinoma (low stage or lymph node metastases) and appear to have better overall prognoses than those with aberrant p53 expression. Whether these tumors represent clear cell carcinomas with tumor progression due to the aquisition of TP53 mutations or hybrid serous/clear cell carcinomas is unknown at this time.
Category: Gynecologic & Obstetrics

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 177, Tuesday Morning

 

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