Outcomes of Radiotherapy for Mesenchymal and Non-Mesenchymal Subtypes of Gastric Cancer

Neoadjuvant versus adjuvant radiotherapy for resectable locally advanced gastric cancer: A SEER population analysis

Background

There is a lack of evidence on whether resectable locally advanced gastric cancer (LAGC) patients could benefit from neoadjuvant or adjuvant radiotherapy (RT).

Methods

Patients with surgically diagnosed LAGC from 2004 to 2015 were retrieved from the SEER database. Kaplan-Meier method and the log-rank test were used to evaluate survival analysis between neoadjuvant and adjuvant RT. Univariate Cox regression was used to evaluate the hazard ratio (HR) and 95 % confidence interval (CI).

Results

A total of 4790 LAGC patients who treated with surgery and RT were identified, including 3187 patients with intestinal subtype and 1603 patients with diffuse subtype. For patients with both intestinal and diffuse subtypes, median cancer-specific survival (mCSS) was better with adjuvant RT or neoadjuvant RT. Moreover, patients benefited more from adjuvant RT than neoadjuvant RT (intestinal subtype: mCSS 49 vs. 36 months, P < 0.001; diffuse subtype: mCSS 32 vs. 26 months, P = 0.050). Further analyses showed that patients with intestinal subtype and T1-2N+, T3N-, T3N+ subgroups, as well as patients with diffuse subtype and T1-2N+ and T3N+ subgroups benefited more from adjuvant RT than those with neoadjuvant RT. Patients in the diffuse subtype and T3N- subgroups also tended benifit from adjuvant RT and survive. There was no difference in survival between the T4N- and T4N + subgroups of the two subtypes. After propensity score matching, subgroup analysis identified an improved survival in favor of adjuvant RT in the age ≥65 years and female subgroups in diffuse subtypes and T4N+ patients.

Conclusions

For patients with resectable LAGC in the T1-2N+, T3N-, T3N+ clinical subgroups, adjuvant RT yields more benefits than neoadjuvant RT or no RT, which is worthy of prospective clinical trial.

Role of Adjuvant Radiotherapy in Gastric Cancer

Although continuous improvement in the treatment outcome of localized gastric cancer has been achieved through early screening, diagnosis, and treatment and the active application of surgery and adjuvant chemotherapy, the necessity of adjuvant radiotherapy (RT) remains controversial. In this review, based on the results of two recently published randomized phase III studies (Adjuvant Chemoradiation Therapy In Stomach Cancer 2 and ChemoRadiotherapy after Induction chemoTherapy of Cancer in the Stomach) and a meta-analysis of six randomized trials including these two studies, the role of adjuvant RT in gastric cancer was evaluated and discussed, especially in patients who underwent curative gastrectomy with D2 lymphadenectomy. This article also reported the possible indications for adjuvant RT in the current clinical situation and in future research to enable patient-specific treatments according to the risk of recurrence.

Multimodal Therapy of Upper Gastrointestinal Malignancies

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Effect of baseline sarcopenia on adjuvant treatment for D2 dissected gastric cancer: Analysis of the ARTIST phase III trial

BACKGROUND AND PURPOSE

This study evaluated the clinical significance of preoperative sarcopenia according to adjuvant concurrent chemo-radiotherapy (XP-RT) or chemotherapy alone (XP) in the D2 dissected gastric cancer patient cohort of the ARTIST trial.

MATERIALS AND METHODS

Skeletal muscles at the L3 vertebra level from preoperative computed tomography images among the ARTIST trial participants were measured using validated in-house software. Skeletal muscle index (SMI) was defined as the measured skeletal muscle area divided by the square of the height, and sarcopenia was defined according to the Korean-specific cutoff, i.e. L3 SMI ≤ 49 cm²/m² for men and ≤31 cm²/m² for women.

RESULTS

Among the 440 patients in whom we were able to evaluate L3 SMI, 75 (17.0%) met the definition for preoperative sarcopenia. No differences in treatment-related toxicities or treatment compliance were observed according to the presence of preoperative sarcopenia in either treatment arm. In the subgroup of patients without preoperative sarcopenia, recurrence was significantly lower in the XP-RT arm than that in the XP arm (p = 0.02). Recurrence-free survival (RFS) was also significantly higher in the XP-RT arm (p = 0.02, hazard ratio 0.633, 95% confidence interval 0.433-0.926) in this subgroup. In the multivariate analysis, and after adjusting for significant prognostic factors, the superior outcome of XP-RT arm regarding RFS was maintained in the subgroup of the patients without preoperative sarcopenia.

CONCLUSIONS

Superior clinical outcomes of adjuvant XP-RT over XP were only observed in patients without preoperative sarcopenia.