Patterns of response after preoperative intensity-modulated radiation therapy and capecitabine/oxaliplatin in rectal cancer: is there still a place for ecoendoscopic ultrasound?
OBJECTIVE
The main goals of preoperative chemoradiotherapy (CHRT) in rectal cancer are to achieve pathological response and to ensure tumor control with functional surgery when possible. Assessment of the concordance between clinical and pathological responses is necessary to make decisions regarding alternative conservative procedures. The present study evaluates the patterns of response after a preoperative CHRT regimen, and the value of endoscopic ultrasound (EUS) in assessing response.


METHODS
A total of 51 EUS-staged T3 to T4 and/or N0 to N+ rectal cancer patients received preoperative CHRT (intensity-modulated radiation therapy and capecitabine/oxaliplatin (XELOX) followed by radical resection. Clinical response was assesed by EUS. Rates of pathological tumor regression grade (TRG) and lymph node (LN) involvement were determined in the surgical specimen. Clinical and pathological responses were compared, and the accuracy of EUS in assessing response was calculated.


RESULTS
Twenty-four patients (45%) achieved a major pathological response (complete or >95% pathological response (TRG 3+/4)). Sensitivity, specificity, negative predictive value, and positive predictive value of EUS in predicting pathological T response after preoperative CHRT were 77.8%, 37.5%, 60%, and 58%, respectively. The EUS sensitivity, specificity, negative predictive value, and positive predictive value for nodal staging were 44%, 88%, 88%, and 44%, respectively. Furthermore, EUS after CHRT accurately predicted the absence of LN involvement in 7 of 7 patients (100%) with major pathological response of the primary tumor.


CONCLUSIONS
Preoperative IMRT with concomitant XELOX induces favorable rates of major pathological response. EUS has a limited ability to predict primary tumor response after preoperative CHRT, but it is useful for accurately determining LN status. EUS may have a potential value in identifying patients with a very low risk of LN involvement in association with a good pathological response as potential candidates for conservative local surgical protocols.
Arbea
Leire
L
Department of Oncology, Radiation Oncology Division, Clinica Universidad de Navarra, Pamplona, Spain. larbea@unav.es
Díaz-González
Juan A
JA
Subtil
Jose Carlos
JC
Sola
Josu
J
Hernandez-Lizoain
Jose Luis
JL
Martínez-Monge
Rafael
R
Moreno
Marta
M
Aristu
Javier
J
D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D000069287:Capecitabine; D003131:Combined Modality Therapy / Q000379:methods; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000627:therapeutic use; D019160:Endosonography / Q000379:methods*; D005260:Female; D005472:Fluorouracil / Q000031:analogs & derivatives / Q000627:therapeutic use; D006801:Humans; D008198:Lymph Nodes / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods; D010071:Oxaloacetates; D011300:Preoperative Care / Q000379:methods; D012004:Rectal Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D010071:Oxaloacetates; D003841:Deoxycytidine; D000069287:Capecitabine; D005472:Fluorouracil