Incidence, Survival Analysis and Future Perspective of Primary Peritoneal Mesothelioma (PPM): A Population-Based Study from SEER Database.

BACKGROUND

Primary peritoneal mesothelioma (PPM) is a rare and aggressive tumor arising from the visceral and parietal peritoneum. The diagnosis and treatment of PPM are often delayed because of non-specific clinical presentation, and the prognosis is worse. The current study investigated the demographic, clinical, and pathological factors affecting patient prognosis and survival in PPM.

METHODS

Demographic and clinical data of 1998 patients with PPM were extracted from the Surveillance Epidemiology and End Results (SEER) database (1975-2016). The chi-square test, paired -test, and multivariate analysis were used to analyze the data.

RESULTS

The majority of PPM patients were male (56.2%, < 0.005) and Caucasian (90.4%, < 0.005, with a mean age of diagnosis was 69 ± 13 years. The grading, histological, and tumor size information were classified as "Unknown" in most of the cases, but when available, poorly differentiated tumors (8.7%), malignant mesothelioma, not otherwise specified (63.4%) and tumors > 4 cm in size (8%), respectively, were most common, < 0.005. Chemotherapy was administered to 50.6% of patients, followed by resection (29.2%) and radiation (1.5%), < 0.001. The cohort of PPM had a five-year overall survival of 20.3% (±1.1), compared to 43.5% (±5.9), 25.9% (± 8.4), and 18.7% (±1.6) for those with surgery, radiation, or chemotherapy alone, respectively. Poor differentiation (OR = 4.2, CI = 3.3-4.9), tumor size > 4 cm (OR = 3.9, CI = 3.2-4.5), Caucasian race (OR = 2.9, CI = 2.6-4.4), and distant SEER stage (OR = 2.5, CI = 1.1-3.2) were all linked with increased mortality ( < 0.001).

CONCLUSION

An extremely rare and aggressive peritoneal tumor, PPM may be difficult to identify at the time of diagnosis. Radiation therapy likely to have a limited function in the treatment of this condition, with surgery and chemotherapy being the primary choices. All PPM patients should be enrolled in a nationwide registry to improve our understanding of the pathogenesis and identify factors affecting survival.