Neoadjuvant therapy for rectal cancer: histologic response of the primary tumor predicts nodal status.
OBJECTIVE
This study was designed to compare histologic T and N stages in patients with rectal adenocarcinoma undergoing various neoadjuvant radiotherapy regimens and proctectomy, in an attempt to determine if final histologic stage of the mural tumor predicts nodal status.


METHODS
Data were collected from computerized databases at two institutions on 649 consecutive patients who underwent neoadjuvant radiotherapy or chemoradiotherapy and proctectomy for primary adenocarcinoma of the rectum from 1990 to 2002.


RESULTS
Five patients were excluded because of incomplete pathology data sets, leaving a study population of 644. Patients underwent neoadjuvant radiotherapy alone (2000 cGy in 5 fractions, n = 191; or 4500 cGy in 25 fractions, n = 259) or chemoradiation (4500 cGy in 25 fractions with concurrent 5-fluorouracil, n = 194). Histologic stage of the remaining mural tumor (ypT) correlated with nodal status (ypN). Lymph nodes harboring metastatic tumor were found in 1 of 42 (2 percent) ypT0 patients, 2 of 45 (4 percent) ypT1 patients, 43 of 186 (23 percent) ypT2 patients, 158 of 338 (47 percent) ypT3 patients, and 16 of 33 (48 percent) ypT4 patients ( P < 0.001, chi-squared test). The probability of finding ypN+ disease was 3 of 87 (3 percent) in patients with ypT0-1 residual primary tumors vs. 220 of 557 (39 percent) in patients with ypT2-4 residual primary tumors ( P < 0.0001; Fisher's exact test).


CONCLUSIONS
Nodal metastases are rare in patients whose mural tumor burden shrinks to ypT0-1 after neoadjuvant radiotherapy. If transanal excision is offered to select patients with distal rectal cancer, it is reasonable to select those who have an excellent clinical response to neoadjuvant therapy for transanal excision, and then reserve proctectomy for patients proven to have residual ypT2-4 disease.
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Thomas E
TE
Division of Colon and Rectal Surgery, Western Pennsylvania Hospital--Clinical Campus of Temple University School of Medicine, Pittsburgh, Pennsylvania 15224, USA.
Andujar
Jose E
JE
Caushaj
Philip F
PF
Johnston
Douglas R
DR
Dietz
David W
DW
Myerson
Robert J
RJ
Fleshman
James W
JW
Birnbaum
Elisa H
EH
Mutch
Matthew G
MG
Kodner
Ira J
IJ
D000230:Adenocarcinoma / Q000473:pathology* / Q000628:therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D017024:Chemotherapy, Adjuvant / Q000379:methods; D003082:Colectomy; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy / Q000379:methods*; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D018714:Radiotherapy, Adjuvant / Q000379:methods; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D012074:Remission Induction; D016896:Treatment Outcome
D000970:Antineoplastic Agents