Bromodeoxyuridine labeling index as an indicator of early tumor response to preoperative radiotherapy in patients with rectal cancer.
OBJECTIVE
Assessment of tumor proliferation rate using Bromodeoxyuridine labeling index (BrdUrdLI) as a possible predictor of rectal cancer response to preoperative radiotherapy (RT).


METHODS
Ninety-two patients were qualified either to short RT (5 Gy/fraction/5 days) and surgery about 1 week after RT (schedule I), or to short RT and 4-5 weeks interval before surgery (schedule II). Tumor samples were taken twice from each patient: before RT and at the time of surgery. The samples were incubated with BrdUrd for 1 h at 37 degrees C, and the BrdUrdLI was calculated as a percentage of BrdUrd-labeled cells.


RESULTS
Thirty-eight patients were treated according to schedule I and 54 patients according to schedule II. Mean BrdUrdLI before RT was 8.5% and its value did not differ between the patients in the two compared groups. After RT tumors showed statistically significant growth inhibition (reduction of BrdUrdLI). As the pretreatment BrdUrd LI was not predictive for early clinical and pathologic tumor response, prognostic role of the ratio of BrdUrdLI after to BrdUrdLI before RT was considered. The ratios were calculated separately for fast (BrdUrd LI>8.5%) and slowly (BrdUrd LI<or=8.5%) proliferating tumors and correlated with overall treatment time (OTT, i.e., time from the first day of RT to surgery). One month after RT, accelerated proliferation was observed only in slowly proliferating tumors.


CONCLUSIONS
Pretreatment BrdUrdLI was not predictive for early clinical and pathologic tumor response. The ratio after/before RT BrdUrdLI was correlated to inhibition of proliferation in responsive tumors.
Gasinska
Anna
A
Department of Applied Radiobiology, Center of Oncology, Garncarska 11, 31-115, Krakow, Poland. z5gasins@cyf-kr.edu.pl
Skolyszewski
Jan
J
Popiela
Tadeusz
T
Richter
Piotr
P
Darasz
Zbigniew
Z
Nowak
Krystyna
K
Niemiec
Joanna
J
Biesaga
Beata
B
Adamczyk
Agnieszka
A
Bucki
Krzysztof
K
Malecki
Krzysztof
K
Reinfuss
Marian
M
Kowalska
Teresa
T
D000230:Adenocarcinoma / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D000328:Adult; D000368:Aged; D001973:Bromodeoxyuridine / Q000493:pharmacokinetics; D049109:Cell Proliferation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D012004:Rectal Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D016196:S Phase
D001973:Bromodeoxyuridine