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Radiother Oncol. 2014 Oct;113(1):1-9. doi: 10.1016/j.radonc.2014.08.035. Epub 2014 Oct 1.

Impact of radiotherapy boost on pathological complete response in patients with locally advanced rectal cancer: a systematic review and meta-analysis.

Author information

1
Department of Radiation Oncology, University Medical Center, Utrecht, The Netherlands. Electronic address: j.p.m.burbach-2@umcutrecht.nl.
2
Department of Radiology, University Medical Center, Utrecht, The Netherlands.
3
Department of Radiation Oncology, University Medical Center, Utrecht, The Netherlands.
4
Trial Bureau Imaging Division, University Medical Center, Utrecht, The Netherlands.

Abstract

PURPOSE:

We conducted a systematic review and meta-analysis to quantify the pathological complete response (pCR) rate after preoperative (chemo)radiation with doses of ⩾60Gy in patients with locally advanced rectal cancer. Complete response is relevant since this could select a proportion of patients for which organ-preserving strategies might be possible. Furthermore, we investigated correlations between EQD2 dose and pCR-rate, toxicity or resectability, and additionally between pCR-rate and chemotherapy, boost-approach or surgical-interval.

METHODS AND MATERIALS:

PubMed, EMBASE and Cochrane libraries were searched with the terms 'radiotherapy', 'boost' and 'rectal cancer' and synonym terms. Studies delivering a preoperative dose of ⩾60 Gy were eligible for inclusion. Original English full texts that allowed intention-to-treat pCR-rate calculation were included. Study variables, including pCR, acute grade ⩾3 toxicity and resectability-rate, were extracted by two authors independently. Eligibility for meta-analysis was assessed by critical appraisal. Heterogeneity and pooled estimates were calculated for all three outcomes. Pearson correlation coefficients were calculated between the variables mentioned earlier.

RESULTS:

The search identified 3377 original articles, of which 18 met our inclusion criteria (1106 patients). Fourteen studies were included for meta-analysis (487 patients treated with ⩾60 Gy). pCR-rate ranged between 0.0% and 44.4%. Toxicity ranged between 1.3% and 43.8% and resectability-rate between 34.0% and 100%. Pooled pCR-rate was 20.4% (95% CI 16.8-24.5%), with low heterogeneity (I2 0.0%, 95% CI 0.00-84.0%). Pooled acute grade ⩾3 toxicity was 10.3% (95% CI 5.4-18.6%) and pooled resectability-rate was 89.5% (95% CI 78.2-95.3%).

CONCLUSION:

Dose escalation above 60 Gy for locally advanced rectal cancer results in high pCR-rates and acceptable early toxicity. This observation needs to be further investigated within larger randomized controlled phase 3 trials in the future.

KEYWORDS:

Boost radiation; Locally advanced rectal cancer; Meta-analysis; Pathologic complete response; Systematic review

PMID:
25281582
DOI:
10.1016/j.radonc.2014.08.035
[Indexed for MEDLINE]
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