E. Strong (ed.). Gastric cancer. Principles and practice. Springer (2015)
In the modern era, there are no large US or European studies that have evaluated a purely adjuvant chemotherapy approach following surgery. However, older studies did investigate this approach. An individual patient data meta-analysis was performed on 3838 patients enrolled in 17 randomized studies between 1974–2001; most of these studies enrolled < 200 patients and included studies performed in the USA, Europe, and Asia . The meta-analysis revealed a statistically significant benefit in terms of OS (HR 0.82; 95% CI 0.76–0.90; p < 0.001) and DFS (HR 0.82; 95% CI 0.75–0.90, p < 0.001). This translated into a 6% absolute improvement in 5-year OS.
Partly because of the significantly superior outcomes with surgery alone, the standard of care in East Asia is for upfront surgery followed by adjuvant chemotherapy. To date, two trials in East Asia of resectable gastric cancer have found a benefit for adjuvant fluoropyrimidines as monotherapy or in combination with a platinum agent. Again, whether the results of these studies can be fully extrapolated to a Western population is not known. The results are summarized in Table 21.3.
The Adjuvant Chemotherapy Trial of TS-1 for Gastric Cancer (ACTS-GC) study was performed in Japan. In this study of 1059 patients with stage II/III gastric cancer who had undergone D2 resections, patients were randomized to 1 year of adjuvant S-1 versus observation . Five-year outcomes for this trial were updated, confirming that adjuvant S-1 is associated with significant improvements in 5-year OS (71.7 vs. 61.1%, HR 0.67, 95% CI 0.54–0.83) compared to observation alone .
The second trial is the capecitabine and oxaliplatin adjuvant study in stomach cancer (CLASSIC) trial, which was performed in 1035 East Asian patients who had undergone a D2 resection of stage II-IIIB gastric cancer . Patients were randomized to 6 months of adjuvant capecitabine/ oxaliplatin versus observation. Updated survival data confirm improved 5-year OS for patients who received chemotherapy (78 vs. 69%, HR 0.66, p = 0.0015); 5-year DFS was also improved (68 vs. 53%, HR 0.58, p < 0.0001) .
Table 21.3. Results of phase III postoperative chemotherapy trials in gastric cancer
On the other hand, a lack of benefit for adding a taxane to a fluoropyrimidine in the adjuvant setting was revealed by the results of the recently published SAMIT study conducted in Japan . One thousand, four hundred and thirty-three evaluable patients with T4a or T4b tumors who had undergone initial surgery were randomized to receive either an oral fluoropyrimidine alone or paclitaxel preceding it. There was no improvement in 3-year DFS for the group that also received a taxane (57.2 vs. 54.0%, p = 0.273), suggesting that more chemotherapy in an unselected population may not be a beneficial strategy.
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