Determinants of Epstein-Barr virus-positive gastric cancer: an international pooled analysis

BACKGROUND

Meta-analyses of the published literature indicate that about 9% of gastric cancers contain Epstein-Barr virus (EBV), with consistent and significant differences by sex and anatomic subsite. This study aimed to identify additional determinants of EBV positivity and their joint effects.

METHODS

From 15 international populations with consistent laboratory testing for EBV, we pooled individual-level data for 5081 gastric cancer cases including information on age, sex, subsite, histologic type, diagnostic stage, geographic region, and period of diagnosis. First, we combined population-specific EBV prevalence estimates using random effects meta-analysis. We then aggregated individual-level data to estimate odds ratios of EBV positivity in relation to all variables, accounting for within-population clustering.

RESULTS

In unadjusted analyses, EBV positivity was significantly higher in males, young subjects, non-antral subsites, diffuse-type histology, and in studies from the Americas. Multivariable analyses confirmed significant associations with histology and region. Sex interacted with age (P=0.003) and subsite (P=0.002) such that male predominance decreased with age for both subsites. The positivity of EBV was not significantly associated with either stage or time period.

CONCLUSION

Aggregating individual-level data provides additional information over meta-analyses. Distinguishing histologic and geographic features as well as interactions among age, sex, and subsite further support classification of EBV-associated gastric cancer as a distinct aetiologic entity.

Malignant phyllodes tumor

The study aims to evaluate the survival and prognosis of patients with malignant phyllodes tumor. Between 1982 and 1998, 37 women with malignant phyllodes tumor were treated at the Regional Cancer Center, Trivandrum. Twelve patients were recurrent. Survival was estimated using the Kaplan-Meier method. Patient, disease, and treatment factors were compared using log-rank test. The Cox-proportional hazard model was employed to identify the prognostic factors. Thirty-six patients had surgery. Twenty-five patients received postoperative radiotherapy, and 2 received chemotherapy in addition. The median follow-up was 43 months (range 1-170 months). Eight patients failed locally, and 7 of these were successfully salvaged by surgery. The 5-year overall survival was 74.2% (95% CI, 0.44 to 0.89), whereas 5-year disease-free survival was 59.6% (95% CI, 0.39 to 0.7). The margin of surgical excision was found to be the only independent prognostic factor (p=0.003). However, patients with tumor size more than 5 cm (hazard ratio 2.9) were found to have increased hazard, whereas those receiving adjuvant radiotherapy (hazard ratio 0.6), married women (hazard ratio 0.4), and those women over the age of 35 years (hazard ratio 0.7) showed a decreased hazards. Cystosarcoma phyllodes is a rare malignancy of the female breast. Surgery with adequate margins is the primary treatment. Adjuvant radiotherapy appears to improve the disease-free survival.