Is step section necessary for determination of complete pathological response in rectal cancer patients treated with preoperative chemoradiotherapy?
OBJECTIVE
To assess the efficacy of the step section for determination of pathological complete response (pCR) in rectal cancer treated with preoperative chemoradiotherapy (CRT).


RESULTS
Of 709 patients with rectal cancer who received preoperative CRT, 88 were initially diagnosed as having pCR. These 88 patients were re-evaluated after two-level step sections of the entire tumour by using Dworak's regression grade. Additional serial step sections revealed residual tumour cells in seven of 88 patients (7.95%), all of whom were upgraded to regression grade 3 (near total regression) from regression grade 4 (total regression). Of these seven patients, one (14.3%) showed tumour recurrence, compared with 11 of 81 (13.6%) patients with a final regression grade of 4. Neither recurrence rate nor disease-free survival rate differed significantly between these two groups (P > 0.5). Calcification was significantly more frequent in grade 3 than in grade four patients (71.4% versus 32.1%; P = 0.037), and acellular mucin pools were associated with better disease-free survival (P = 0.022).


CONCLUSIONS
Stratifying patient outcome by final regression grade after step section did not yield different outcomes in patients with initial pCR. If residual tumour cells are not identified on initial meticulous examination, further processing of step sections is not necessary.
Department of Pathology, Research Institute and Hospital, National Cancer Center, Goyang, Korea.
Seog Yun
SY
Park
Hee Jin
HJ
Chang
Dae Yong
DY
Kim
Kyung Hae
KH
Jung
Sun Young
SY
Kim
Ji Won
JW
Park
Jae Hwan
JH
Oh
Seok-Byung
SB
Lim
Hyo Seong
HS
Choi
Seung-Yong
SY
Jeong
D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D059248:Chemoradiotherapy; D005260:Female; D006652:Histological Techniques; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging / Q000379:methods; D018365:Neoplasm, Residual / Q000473:pathology; D010340:Pathology, Surgical / Q000379:methods / Q000592:standards*; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy*
D000970:Antineoplastic Agents