Surveillance, epidemiology, and end results-based analysis of the impact of preoperative or postoperative radiotherapy on survival outcomes for T3N0 rectal cancer.
OBJECTIVE
Preoperative chemoradiation has been established as standard of care for T3/T4 node-positive rectal cancer. Recent work, however, has called into question the overall benefit of radiation for tumors with lower risk characteristics, particularly T3N0 rectal cancers. We retrospectively analyzed T3N0 rectal cancer patients and examined how outcomes differed according to the sequence of treatment received.


METHODS
The Surveillance, Epidemiology, and End Results (SEER) database was used to analyze T3N0 rectal cancer cases diagnosed between 1998 and 2008. Treatment consisted of surgery alone (No RT), preoperative radiation followed by surgery (Neo-Adjuvant RT), or surgery followed by postoperative radiation (Adjuvant RT). Demographic and tumor characteristics of the three groups were compared using t-tests for the comparison of means. Survival information from the SEER database was utilized to estimate cause-specific survival (CSS) and to generate Kaplan-Meier survival curves. Multivariate analysis (MVA) of features associated with outcomes was conducted using Cox proportional hazards regression models with Adjuvant RT, Neo-Adjuvant RT, No RT, histological grade, tumor size, year of diagnosis, and demographic characteristics as covariates.


RESULTS
10-Year CSS estimates were 66.1% (95% CI 62.3-69.6%; P=0.02), 73.5% (95% CI 68.9-77.5%; P=0.02), and 76.1% (95% CI 72.4-79.4%; P=0.02), for No RT, Neo-Adjuvant RT, and Adjuvant RT, respectively. On MVA, Adjuvant RT (HR=0.688; 95% CI, 0.578-0.819; P<0.001) was associated with significantly decreased risk for cancer death. By contrast, Neo-Adjuvant RT was not significantly associated with improved cancer survival (HR=0.863; 95% CI, 0.715-1.043; P=0.127).


CONCLUSIONS
Adjuvant RT was associated with significantly higher CSS when compared with surgery alone, while the benefit of Neo-Adjuvant RT was not significant. This indicates that surgery followed by Adjuvant RT may still be an important treatment plan for T3N0 rectal cancer with potentially significant survival advantages over other treatment sequences.
Department of Radiation Oncology, Stich Radiation Center, Weill Cornell Medical College of Cornell University, New York, NY, United States.
Luke C
LC
Peng
Department of Surgery, Weill Cornell Medical College of Cornell University, New York, NY, United States.
Jeffrey
J
Milsom
Department of Surgery, Weill Cornell Medical College of Cornell University, New York, NY, United States.
Kelly
K
Garrett
Department of Surgery, Weill Cornell Medical College of Cornell University, New York, NY, United States.
Govind
G
Nandakumar
Department of Radiation Oncology, Stich Radiation Center, Weill Cornell Medical College of Cornell University, New York, NY, United States.
Shana
S
Coplowitz
Department of Radiation Oncology, Stich Radiation Center, Weill Cornell Medical College of Cornell University, New York, NY, United States.
Bhupesh
B
Parashar
Department of Radiation Oncology, Stich Radiation Center, Weill Cornell Medical College of Cornell University, New York, NY, United States.
Dattatreyudu
D
Nori
Department of Radiation Oncology, Stich Radiation Center, Weill Cornell Medical College of Cornell University, New York, NY, United States.
K S
KS
Clifford Chao
Department of Radiation Oncology, Stich Radiation Center, Weill Cornell Medical College of Cornell University, New York, NY, United States. Electronic address: gaw9008@med.cornell.edu.
A G
AG
Wernicke
D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020360:Neoadjuvant Therapy / Q000379:methods*; D016016:Proportional Hazards Models; D018714:Radiotherapy, Adjuvant / Q000379:methods; D012004:Rectal Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D012189:Retrospective Studies; D018426:SEER Program; D016896:Treatment Outcome
Outcomes; Post-operative; Pre-operative; Radiation; Rectal cancer; SEER; T3N0