Esophageal cancer: Proton outshines photon therapy in safety, efficacy

In the treatment of patients with esophageal cancer, proton-based radiotherapy appears to yield better safety and efficacy outcomes including organs at risk (OARs) doses, toxicity, and prognosis when compared with photon therapy, according to a meta-analysis.

For the study, researchers searched multiple online databases for articles in which proton and photon therapies were compared based on OARs dosimetric outcomes, prognosis (overall survival [OS], progression-free survival [PFS], and objective response rate [ORR]), and radiation-related toxic effects. A total of 45 studies were included in the meta-analysis.

Pooled data showed that OARs dose was significantly reduced with proton therapy than with photon therapy.

Meanwhile, photon therapy was associated with poorer OS (hazard ratio [HR], 1.31, 95 percent confidence interval [CI], 1.07–1.61; I²=11 precent), but PFS did not differ relative to proton therapy. Of note, the subgroup of patients who received radical therapy with photon therapy had worse OS (HR, 1.42, 95 percent CI, 1.14–1.78; I²=34 percent) and PFS (HR, 1.48, 95 percent CI, 1.06–2.08; I²=7 percent). No significant difference in the pathological complete response rate was noted between proton and photon therapies.

In terms of safety, proton therapy was associated with significantly lower grade ≥2 radiation pneumonitis and pericardial effusion, and grade ≥4 lymphocytopenia.

In a single-rate analysis of proton therapy, the respective OS and PFS rates were 89 percent and 65 percent at 1 year, 71 percent and 56 percent at 2 years, 63 percent and 48 percent at 3 years, and 56 percent and 42 percent at 5 years. The frequency of grade ≥2 radiation esophagitis was 50 percent, grade ≥2 radiation pneumonitis was 2 percent, grade ≥2 pleural effusion was 4 percent, grade ≥2 pericardial effusion was 3 percent, grade ≥3 radiation esophagitis was 8 percent, and grade ≥4 lymphocytopenia was 17 percent.