Myung Mi Cho


Background: European trials evaluating the effect of preoperative (PreOP) versus postoperative chemoradiotherapy (PostOP CRT) found no survival benefit. However, the effect of a change from PostOP to PreOP CRT has not been evaluated in a population-based setting. We sought to evaluate multimodal treatment changes and overall survival for perioperative (PeriOP) CRT versus surgery alone and for PreOP versus PostOP CRT from 1994 through 2009 among patients receiving radical surgery for stage II and III rectal cancer (RC).

Patients and Methods: We conducted a nonconcurrent cohort study evaluating demographic predictors of multimodal therapy for stage II and III RC using the diverse California Cancer Registry population-based data. First, we compared patients who received only surgery versus those receiving surgery plus PeriOP CRT. Second, we compared patients who received PreOP CRT with those receiving PostOP CRT. Cox proportional hazards regression was used to assess survival over 192 months in both study groups, adjusting for date of surgery, stage, age, gender, race/ethnicity, and socioeconomic status (SES).

Results: The Cox proportional hazards regression analysis showed that PeriOP CRT was associated with lower mortality, and the hazards ratio (HR) decreased with each time period (1994-1997: HR=0.73, 0.65-0.83; 1998-2001: HR=0.66,0.60-0.73; 2002-2005: HR=0.55, 0.49-0.61; and 2006-2009: HR=0.36, 0.31-0.43) (Ptrend < 0.0001). For PreOP versus PostOP CRT, our findings showed a stepwise increase (OR, 95% Cl) in the use of PreOP CRT across three time-periods (1994-1997: OR=0.07, 0.06-0.08; 1998- 2005: OR=0.33, 0.29-0.36; 2006-2009: OR=1) which was concomitant with publication of findings from European trials. However, we did not find a clear survival benefit for PreOP versus PostOP CRT.

Conclusions: Younger age-groups were more likely to receive PeriOP and PreOP CRT. The same was true for males compared to females. Survival was significantly better among patients receiving PeriOP CRT versus surgery alone, and the survival benefit increased over the time-period of our study, suggesting CRT procedures have been modified over time. Our study identified a clear shift in timing of PeriOP CRT from PostOP to PreOP. However, we found no clear support for a survival benefit associated with this shift. Our findings are in line with the results from clinical trials.

LLU Discipline



Epidemiology and Biostatistics


School of Public Health

First Advisor

Raymond Knutsen

Second Advisor

Kevork Kazanjian

Third Advisor

John William Morgan

Degree Name

Doctor of Public Health (DrPH)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Rectal Neoplasms -- therapy -- California; Rectal Neoplasms -- mortality -- statistics and numerical data -- California; Colonic Neoplasms -- therapy -- California; Colonic Neoplasms -- mortality -- statistics and numerical data -- California; Neoplasm Recurrence, Local -- mortality -- statistics and numerical data -- California; Survival Rate -- California -- 1994-2009.



Page Count

x; 77

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website


Loma Linda University. Del E. Webb Memorial Library. University Archives