title: MRI Risk Stratification for Tumor Relapse in Rectal Cancer Achieving Pathological Complete Remission after Neoadjuvant Chemoradiation Therapy and Curative Resection.
abstract: OBJECTIVE
  Rectal cancer patients achieving pCR are known to have an excellent prognosis, yet no widely accepted consensus on risk stratification and post-operative management (e.g., adjuvant therapy) has been established. This study aimed to identify magnetic resonance imaging (MRI) high-risk factors for tumor relapse in pathological complete remission (pCR) achieved by rectal cancer patients who have undergone neoadjuvant concurrent chemoradiation therapy (CRT) and curative resection.
  
  
  METHODS
  We analyzed 88 (male/female = 55/33, median age, 59.5 years [range 34-78]) pCR-proven rectal cancer patients who had undergone pre-CRT MRI, CRT, post-CRT MRI and curative surgery between July 2005 and December 2012. Patients were observed for post-operative tumor relapse. We analyzed the pre/post-CRT MRIs for parameters including mrT stage, mesorectal fascia (mrMRF) status, tumor volume, tumor regression grade (mrTRG), nodal status (mrN), and extramural vessel invasion (mrEMVI). We performed univariate analysis and Kaplan-Meier survival analysis.
  
  
  RESULTS
  Post-operative tumor relapse occurred in seven patients (8.0%, n = 7/88) between 5.7 and 50.7 (median 16.8) months. No significant relevance was observed between tumor volume, volume reduction rate, mrTRG, mrT, or mrN status. Meanwhile, positive mrMRF (Ppre-CRT = 0.018, Ppre/post-CRT = 0.006) and mrEMVI (Ppre-CRT = 0.026, Ppre-/post-CRT = 0.008) were associated with higher incidence of post-operative tumor relapse. Kaplan-Meier survival analysis revealed a higher risk of tumor relapse in patients with positive mrMRF (Ppre-CRT = 0.029, Ppre-/post-CRT = 0.009) or mrEMVI (Ppre-CRT = 0.024, Ppre-/post-CRT = 0.003).
  
  
  CONCLUSIONS
  Positive mrMRF and mrEMVI status was associated with a higher risk of post-operative tumor relapse of pCR achieved by rectal cancer patients, and therefore, can be applied for risk stratification and to individualize treatment plans.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, 120-752, Republic of Korea.
authors.forename: Honsoul
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Medical Information, Jungwon University, Goesan, 367-805, Republic of Korea.
authors.forename: Sungmin
authors.initials: S
authors.lastname: Myoung
authors.affiliation: Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, 120-752, Republic of Korea.
authors.forename: Woong Sub
authors.initials: WS
authors.lastname: Koom
authors.affiliation: Department of Surgery, Division of Colon and Rectal Surgery, Yonsei University College of Medicine, Seoul, 120-752, Republic of Korea.
authors.forename: Nam Kyu
authors.initials: NK
authors.lastname: Kim
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, 120-752, Republic of Korea.
authors.forename: Myeong-Jin
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Internal Medicine, Yonsei University College of Medicine, Seoul, 120-752, Republic of Korea.
authors.forename: Joong Bae
authors.initials: JB
authors.lastname: Ahn
authors.affiliation: Department of Surgery, Division of Colon and Rectal Surgery, Yonsei University College of Medicine, Seoul, 120-752, Republic of Korea.
authors.forename: Hyuk
authors.initials: H
authors.lastname: Hur
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul, 120-752, Republic of Korea.
authors.forename: Joon Seok
authors.initials: JS
authors.lastname: Lim
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D059248:Chemoradiotherapy; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009364:Neoplasm Recurrence, Local; D011182:Postoperative Care / Q000379:methods*; D012004:Rectal Neoplasms / Q000473:pathology* / Q000628:therapy*; D012007:Rectum / Q000187:drug effects / Q000528:radiation effects / Q000601:surgery; D012074:Remission Induction; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012307:Risk Factors