Incidence and survival trends for appendiceal mucinous adenocarcinoma: an analysis of 3237 patients in the Surveillance, Epidemiology, and End Results database

Appendiceal adenocarcinoma is associated with better prognosis than cecal adenocarcinoma: a population-based comparative survival study

OBJECTIVE

Although appendiceal cancer remains a rare gastrointestinal malignancy compared with colorectal cancer, incidence rates of appendiceal cancer have increased in the last two decades. Appendiceal and cecal adenocarcinomas have distinct genomic profiles, but chemotherapy protocols for these malignancies are the same and survival outcomes between them have not been compared extensively. To this end, we conducted a comparative survival analysis of appendiceal and cecal adenocarcinomas.

DESIGN

Using the Surveillance, Epidemiology and End Results (SEER) database, we identified individuals ≥30 years of age with appendiceal or cecal adenocarcinoma from 1975 to 2016. Demographic, clinical and county-level socioeconomic data were extracted using SEER*Stat software. Survival was compared by Mantel-Haenszel log-rank test, and survival curves were generated using the Kaplan-Meier method. Relative HRs for death in the 5-year period following diagnosis were calculated using multivariable Cox regression analysis, adjusted for all other covariates. The significance level was set at p<0.05 for two-tailed tests. Data were analysed using SAS V.9.4 and R software.

RESULTS

We identified 6491 patients with appendiceal adenocarcinoma and 99 387 patients with cecal adenocarcinoma. Multivariable Cox regression analysis demonstrated significantly higher cancer-specific and overall survival in appendiceal adenocarcinoma compared with cecal adenocarcinoma. Male sex, older age, earlier year of diagnosis, black race, single marital status, non-Hispanic ethnicity, and non-mucinous histology were associated with increased mortality rates. In addition, counties with lower percentage of individuals below the poverty line and higher colorectal cancer screening rates had better survival.

CONCLUSION

This is the first study to show greater survival in appendiceal adenocarcinoma compared with cecal adenocarcinoma. We also highlighted novel associations of county-level socioeconomic factors with increased mortality in appendiceal adenocarcinoma. Future efforts to develop targeted molecular therapies and reduce socioeconomic barriers to diagnosis and treatment are warranted to improve survival.

Prevalence and incidence of pseudomyxoma peritonei in urban China: A nationwide retrospective cohort study

BACKGROUND

Pseudomyxoma peritonei (PMP) is an extremely rare condition. Information regarding the disease burden of PMP in developing countries is limited. This study aimed to determine the epidemiology of PMP in China.

METHODS

PMP data were extracted from the national databases of Urban Basic Medical Insurance. All cases were identified using the International Classification of Diseases (ICD) codes and Chinese diagnostic terms. The national prevalence from 2012 to 2016 and incidence in 2016 were estimated.

RESULTS

In total, 153 patients with PMP were identified. The crude prevalence of PMP in 2016 was 2.47 (95% confidence interval [CI] 1.71 to 3.23) per million person-year, with a higher prevalence in females than males. Prevalence increased with age, with the first peak in those aged 15-29 years and the highest in those aged >80 years. The crude incidence of PMP in 2016 was 1.19 (95% CI 0.59 to 1.78) per million person-years. Similar to the prevalence, the rates were higher in women than in men. The incidence also increased with age, with the highest prevalence in those aged >80 years. Besides, the most frequent comorbidities before and after the first diagnosis of PMP were unspecified secondary malignancies and malignancies of unspecified sites, followed by abdominal malignant tumours.

CONCLUSIONS

The rate of PMP was lower in mainland China than in European countries and increased with advancing age. Women were more likely to have PMP than men. Furthermore, an insufficient understanding of this rare disease presents a major challenge in accurately evaluating the disease burden.