Highlights
- •Adjuvant RT for non-rectal colon cancer is controversial, due to limited data.
- •We used the SEER database to examine survival for T4 disease after adjuvant RT.
- •We found a significant improvement in cause-specific survival with this treatment.
Abstract
Purpose
While there is no level 1 evidence supporting the use of adjuvant radiotherapy (RT)
for non-rectal colon cancer in the modern chemotherapy era, there are studies that
suggest a local control benefit. This treatment modality is not part of standard treatment
recommendations, and we hypothesized that adjuvant RT provides a benefit in locally
advanced disease. Due to the limited number who receive post-operative RT, a national
database was searched to provide sufficient power.
Materials and methods
A retrospective analysis using the Surveillance, Epidemiology, and End Results (SEER)
database was performed. Inclusion criteria were: non-rectal colon cancer, AJCC 6th
or 7th edition T4 and M0, oncologic resection, and 1st cancer site. Patients were
excluded for RT prior to or during surgery, or if the sequence of RT was unknown.
Using a Cox proportional hazard model, the relative risk of cause-specific mortality
for “RT after surgery” versus “No RT” was calculated.
Results
21,789 patients were identified who met the inclusion criteria. Of these, only 1001
received adjuvant RT, and 64% were node-positive (53% RT vs. 65% no RT). When comparing
RT vs. no RT, after adjusting for sex, age, N stage, and grade, we determined the
relative risk of death from cancer was 0.8849 (95% CI: 0.8008–0.9779; p = 0.0165),
suggesting that only 14 patients with T4 disease need receive adjuvant radiation to
spare a cancer-related death.
Conclusions
Adjuvant RT is not routinely utilized for definitive treatment of T4 non-rectal colon
cancer, but this analysis shows a significant cause-specific survival benefit.
Keywords
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Article info
Publication history
Published online: January 16, 2019
Accepted:
November 29,
2018
Received in revised form:
November 26,
2018
Received:
June 29,
2018
Identification
Copyright
© 2018 Elsevier B.V. All rights reserved.
