Proliferating cell nuclear antigen and mitotic activity in rectal cancer: predictor of response to preoperative irradiation.
OBJECTIVE
This study examines the association between the pathologic response of rectal cancer after irradiation and its pretreatment proliferative state as assayed by proliferating cell nuclear antigen (PCNA) and mitotic activity.


METHODS
Ninety patients with clinical stage T3 and T4 rectal cancer received preoperative irradiation followed by surgery. Pretreatment tumor biopsies were scored for PCNA activity (number of tumor cells staining immunohistochemically with an anti-PCNA monoclonal antibody) and the number of mitoses per 10 high-powered fields (hpf). Postirradiation surgical specimens were examined for extent of residual disease.


RESULTS
The tumors of 33 of 90 patients (37%) exhibited marked pathologic downstaging (no residual tumor or cancer confined to the rectal wall) after preoperative irradiation. Two features were independently associated with the likelihood of marked pathologic regression after preoperative irradiation: lesion size and PCNA/mitotic activity. When stratified by tumor size, marked tumor regression occurred most frequently in smaller tumors with high PCNA/mitotic activity compared with larger tumors with lower PCNA/mitotic activity. Intermediate downstaging rates were seen for small or large tumors with moderate PCNA/mitotic activity.


CONCLUSIONS
Tumor PCNA/mitotic activity predicts the likelihood of response to irradiation, which may aid in formulating treatment policies for patients with rectal cancer.
Willett
C G
CG
Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Warland
G
G
Cheek
R
R
Coen
J
J
Efird
J
J
Shellito
P C
PC
Compton
C C
CC
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002455:Cell Division / Q000276:immunology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008938:Mitosis; D009687:Nuclear Proteins / Q000032:analysis*; D011237:Predictive Value of Tests; D018809:Proliferating Cell Nuclear Antigen; D012004:Rectal Neoplasms / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery; D013997:Time Factors
D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen