Effect of prior malignancy on the prognosis of gastric cancer and somatic mutation.

BACKGROUND

Cancer survivors have a higher risk of developing secondary cancer, with previous studies showing heterogeneous effects of prior cancer on cancer survivors.

AIM

To describe the features and clinical significance of a prior malignancy in patients with gastric cancer (GC).

METHODS

We identified eligible patients from the Surveillance, Epidemiology, and End Results (SEER) database, and compared the clinical features of GC patients with/without prior cancer. Kaplan-Meier curves and Cox analyses were used to assess the prognostic impact of prior cancer on overall survival (OS) and cancer-specific survival (CSS) outcomes. We also validated our results in The Cancer Genome Atlas (TCGA) cohort and compared mutation patterns.

RESULTS

In the SEER dataset, of the 35492 patients newly diagnosed with GC between 2004 and 2011, 4,001 (11.3%) had at least one prior cancer, including 576 (1.62%) patients with multiple cancers. Patients with a prior cancer history tended to be elderly, with a more localized stage and less positive lymph nodes. The prostate (32%) was the most common initial cancer site. The median interval from initial cancer diagnosis to secondary GC was 68 mo. By using multivariable Cox analyses, we found that a prior cancer history was not significantly associated with OS (hazard ratio [HR]: 1.01, 95% confidence interval [CI]: 0.97-1.05). However, a prior cancer history was significantly associated with better GC-specific survival (HR: 0.82, 95% CI: 0.78-0.85). In TCGA cohort, no significant difference in OS was observed for GC patients with or without prior cancer. Also, no significant differences in somatic mutations were observed between groups.

CONCLUSION

The prognosis of GC patients with previous diagnosis of cancer was not inferior to that of primary GC patients.