Consensus Report of the 2015 Weinman International Conference on Mesothelioma

Epidemiology and trend analysis on malignant mesothelioma in China

Objective

Population-based cancer registration data were used to analyze the epidemiology and trend of malignant mesothelioma in China, and the result would provide basic data for its prevention and control.

Methods

Malignant mesothelioma data in 2013 were retrieved from the database of National Cancer Registry. Malignant mesothelioma incidence and mortality were estimated using age-specific rate by urban/rural and gender according to the national population in 2013. Malignant mesothelioma data from 22 cancer registries were used for trend analysis during 2000–2013.

Results

It is estimated that there were 2,041 new malignant mesothelioma cases and 1,659 malignant mesothelioma deaths occurred in 2013. The crude incidence rate in China were 1.50/10⁶ (males 1.67/10⁶, females 1.32/10⁶), age-standardized incidence rates by Chinese standard population (ASIRC) and by world standard population (ASIRW) were 1.03/10⁶ and 1.02/10⁶, respectively. The crude mortality rate in China was 1.22/10⁶ (males 1.67/10⁶, females 1.32/10⁶), age-standardized mortality rates by Chinese standard population (ASMRC) and by world standard population (ASMRW) were 0.83/10⁶ and 0.81/10⁶, respectively. There was an increasing trend of incidence rate for malignant mesothelioma in registration areas of China during 2000–2013 with annual percentage change (APC) of 2.5% [95% confidence interval (95% CI): 0.6%–4.5%]. After age standardization, no significant differences were observed. No matter for crude mortality rates or age-standardized mortality rates, no significant differences were observed during 2000–2013.

Conclusions

Malignant mesothelioma is the major occupational and environmental neoplasm associated with asbestos exposure. The increasing incidence trend suggests that more attention should be paid on this disease.

Improving the Accuracy of Mesothelioma Diagnosis in China

INTRODUCTION

In the Western world, malignant mesothelioma (MM) is most prevalent in the pleura of older males who have been professionally exposed to asbestos. Information about MM from rapidly industrializing countries such as China is minimal. There is concern that a proportion of MM diagnoses in China may be incorrect because most Chinese physicians do not have experience diagnosing this rare cancer. We recently reported an unusually high incidence of peritoneal MM among eastern Chinese female patients. Here, we review the accuracy of MM diagnoses in China and provide suggestions to improve the accuracy of diagnosis.

METHODS

We reviewed 92 pathological diagnosis of MM in 2002-2015 from two reference centers in the province of Zhejiang in eastern China. We performed a large set of immunohistochemistry analyses to increase the reliability of the diagnosis.

RESULTS

We confirmed the MM diagnosis in 12 of 34 of the pleural tumors (35.3%), in 38 of 56 of the peritoneal tumors (67.9%), and in two of two of the MMs of the tunica vaginalis (100%). MMs were characterized by tumor cells showing nuclear Wilms tumor 1 and calretinin staining and by strong membranous staining for cytokeratin CAM5.2. The results of staining for the epithelial markers carcinoembryonic antigen, thyroid transcription factor-1, MOC31, BerEP4, p63, p40, paired box 8, ER and PR were negative. BRCA1 associated protein 1 nuclear staining was lost in percentages similar to what has been reported for samples from Western countries.

CONCLUSIONS

Our findings suggest that MM-especially in its pleural localization-is often misdiagnosed in eastern China. Identifying pitfalls and possible solutions in the pathological diagnosis of MM will affect both the standard of care and research in China.

High-density array-CGH with targeted NGS unmask multiple noncontiguous minute deletions on chromosome 3p21 in mesothelioma

We used a custom-made comparative genomic hybridization array (aCGH; average probe interval 254 bp) to screen 33 malignant mesothelioma (MM) biopsies for somatic copy number loss throughout the 3p21 region (10.7 Mb) that harbors 251 genes, including BRCA1 (breast cancer 1)-associated protein 1 (BAP1), the most commonly mutated gene in MM. We identified frequent minute biallelic deletions (<3 kb) in 46 of 251 genes: four were cancer-associated genes: SETD2 (SET domain-containing protein 2) (7 of 33), BAP1 (8 of 33), PBRM1 (polybromo 1) (3 of 33), and SMARCC1 (switch/sucrose nonfermentable- SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily c, member 1) (2 of 33). These four genes were further investigated by targeted next-generation sequencing (tNGS), which revealed sequence-level mutations causing biallelic inactivation. Combined high-density aCGH and tNGS revealed biallelic gene inactivation in SETD2 (9 of 33, 27%), BAP1 (16 of 33, 48%), PBRM1 (5 of 33, 15%), and SMARCC1 (2 of 33, 6%). The incidence of genetic alterations detected is much higher than reported in the literature because minute deletions are not detected by NGS or commercial aCGH. Many of these minute deletions were not contiguous, but rather alternated with segments showing oscillating copy number changes along the 3p21 region. In summary, we found that in MM: (i) multiple minute simultaneous biallelic deletions are frequent in chromosome 3p21, where they occur as distinct events involving multiple genes; (ii) in addition to BAP1, mutations of SETD2, PBRM1, and SMARCC1 are frequent in MM; and (iii) our results suggest that high-density aCGH combined with tNGS provides a more precise estimate of the frequency and types of genes inactivated in human cancer than approaches based exclusively on NGS strategy.