The predictive value of apoptosis protease-activating factor 1 in rectal tumors treated with preoperative, high-dose-rate brachytherapy.
BACKGROUND
The objective of this study was to assess the value of apoptosis protease-activating factor 1 (APAF-1) as a predictive marker of response in rectal tumors treated with preoperative, high-dose-rate endorectal brachytherapy.


METHODS
Immunohistochemistry for APAF-1 was performed on 94 rectal tumor biopsy specimens from patients who were treated on a preoperative, high-dose-rate brachytherapy protocol. Tumors were considered positive when > 10% of tumor cells were immunoreactive. The association between APAF-1 expression and tumor response was made using the chi-square test.


RESULTS
Forty-four tumors (43%) were positive for APAF-1. Thirty tumors had complete pathologic tumor regression after preoperative radiotherapy. Of these, 18 tumors were positive for APAF-1. A partial response occurred in 35 tumors. Eighteen tumors (51%) were positive for the protein. Only 8 of 29 nonresponsive tumors (28%) were immunoreactive for APAF-1. A significant association was found between complete tumor regression and positive APAF-1 status (P = 0.018). APAF-1 expression in partially responsive tumors was significantly greater than in nonresponsive tumors (P = 0.03).


CONCLUSIONS
APAF-1 expression in pretreatment rectal tumor biopsy specimens may be useful as a predictive marker of response to preoperative radiotherapy in patients with rectal carcinoma.
Zlobec
Inti
I
Department of Pathology, McGill University, Montreal, Quebec, Canada. inti.zlobec@elf.mcgill.ca
Vuong
Te
T
Compton
Carolyn C
CC
D053477:Apoptotic Protease-Activating Factor 1; D001918:Brachytherapy; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000032:analysis*; D008297:Male; D011300:Preoperative Care; D011379:Prognosis; D011506:Proteins / Q000032:analysis*; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000532:radiotherapy* / Q000601:surgery
C506592:APAF1 protein, human; D053477:Apoptotic Protease-Activating Factor 1; D047908:Intracellular Signaling Peptides and Proteins; D011506:Proteins