“26% Lower Risk of Death”: Chinese Researchers Set New Benchmark for Adjuvant Gastric Cancer Therapy

A large clinical trial by Chinese researchers found that using oxaliplatin plus S-1 (SOX) as adjuvant chemotherapy after surgery for stage 2-3 gastric cancer can lower the risk of death by 26% compared with S-1 alone, the existing standard.

According to BioOn on the 15th (local time), a team led by Li Yuanfang of the Cancer Center at Sun Yat-sen University in China published results from the phase 3 CAPITAL trial, which compared SOX combination therapy with S-1 alone, in the international journal Med.

The researchers divided 724 patients with stage 2-3 gastric or gastroesophageal junction adenocarcinoma who had undergone D2 curative surgery into an SOX group (362 patients) and an S-1-alone group (362 patients), and followed them for an average of 74 months.

The 5-year overall survival rate was 70.9% in the SOX group, higher than the 62.9% in the S-1-alone group. The risk of death was 26% lower.

The 5-year disease-free survival rate was also higher in the SOX group, at 66.2% versus 55.6% in the S-1-alone group, corresponding to a 24% reduction in recurrence risk.

Among high-risk patients with stage 3 disease, the 5-year overall survival rate was 63.9% in the SOX group, more than 13 percentage points higher than the 50.5% in the S-1-alone group. Disease-free survival also differed, at 58.0% versus 42.0%.

The locoregional recurrence rate was substantially lower in the SOX group, at 2% (6 patients), than in the S-1-alone group, at 7% (25 patients).

In terms of safety, the incidence of grade 3-4 treatment-related adverse events was higher in the SOX group, at 25%, than in the S-1-alone group, at 13%. The most common adverse events were neutropenia (13% versus 7%), thrombocytopenia (3% versus less than 1%) and nausea (4% versus less than 1%).

However, all adverse events were clinically manageable, and there were no treatment-related deaths. The proportions of patients who had their S-1 dose reduced were also similar in the two groups, at 21% versus 20%, indicating that combination therapy did not reduce medication adherence.

The researchers said this was the largest phase 3 trial comparing SOX therapy with S-1 alone and had the longest follow-up. They said it addressed limitations of the earlier ARTIST2 study, which had a small sample size and lacked overall survival data.

The study is significant because it provides high-quality evidence in an Asian population, with all participants being Chinese and the research led by Chinese investigators. The researchers added that future studies should directly compare oxaliplatin-based (SOX) and docetaxel-based (DS) regimens and investigate biomarker-based precision adjuvant therapy.