The reported incidence of malignant mesothelioma (MM) in China is 1.5 cases per million population, significantly less than in other countries.1 In China, the prevalence of MM in different regions is unknown 1, and only 15% of MM were associated with asbestos exposure1,2 compared to more than 70% in most countries3,4.
We examined all malignant tumors of the pleura and peritoneum for which a diagnosis of MM was diagnosed, from January 1, 2002 to December 31, 2015, at the Zhejiang Cancer Hospital (ZJCH), which is the largest hospital on cancer in Hangzhou, China, where the asbestos industry does not exist. and near the Yuyao People's Hospital (112 km), located in China's Asbestos Textile Industrial Zone in Yuyao, China, where most of the patients are exposed to asbestos. We examined a total of 92 MM: 34 in the pleura, 56 in the peritoneum and 2 in the tunica vaginalis.
Exposure to asbestos was determined by a qualified oncologist (W.M., Z. Guo or Z. Gao), who interviewed patients about their work and family history. People who worked in occupations where asbestos exposure was likely or who grew up or lived in families where others worked in the textile industry or asbestos-related trades were identified as exposed asbestos. This retrospective study was approved by the Zhejiang Cancer Hospital Ethics Committee and the Ethics Committee of the Zhejiang Academy of Medical Sciences. Formalin-fixed, paraffin-embedded tissue was obtained from blocks preserved in the Department of Pathology, Zhejiang Cancer Hospital, and Yuyao Hospital. Patient information was obtained through medical records and interviews with the patient and his family. All patients gave verbal informed consent and the data was not identified.
By examining the histological results using a large immunohistochemical panel, we confirmed the diagnosis of MM in 28 patients of ZJCH and 24 of People's Hospital of Yuyao (52 out of 92 cases [57%]). The male / female ratio was about 1: 4 (19%, 95% CI, 10% -32%), compared to 4: 1 (80%) in the United States (z = 11.0, P <0.001) . The pleural / peritoneal MM ratio was approximately 1: 3 (24%, 95% CI, 13% to 38%) compared to 5: 1 (83%) in the United States (z = 11.2, p < 0.001). Mean age (SD) at diagnosis was 50.6 (7.9) years (95% CI, 48.4 to 52.7 years) compared to 72 (9.5) years in the United States ( t51 = 19.3, p <0.001). Twenty of the 52 MM (5 in the pleura, 14 in the peritoneum and 1 in the tunica vaginalis) occurred in people exposed to asbestos (38%, 95% CI, 25% -53%): 2 of 28 (7%). %). ; 95% CI, 1% -23%) at the ZJCH and 18 of 24 (75%, 95% CI, 53% to 90%) at the Yuyao People's Hospital. The calculated tomograms available for 16 of the 28 MMs detected at ZJCH were exposed to asbestos in 2 out of 16 cases (13%, 95% CI, 2% to 38%). Asbestos-related MM cases occurred in 19 women and 1 man. Nine of 52 MM (17%, 95% CI, 8% to 30%) occurred in people aged 40 or younger, compared to less than 1% in the same age group in the United States3 (Table 1 and Table 1). Table 2).
The higher prevalence of peritoneal and pleural MM in China, particularly among unexposed young women, is unique3,4,6. At first, we thought that asbestos was the main cause, as 13 of the 18 peritoneal MM (72%, 95% CI, 46%). -90%) of the Yuyao People's Hospital occurred in women exposed to asbestos. However, only 1 of the 14 MM peritoneum (7%, 95% CI, 0% to 34%) of the ZJCH was associated with asbestos. With the exception of asbestos exposure, no significant demographic differences were observed between ZJCH and Yuyao People's Hospital (Table 1 and Table 2), suggesting that asbestos may not to be the leading cause of MM in these women. These findings point to a unique opportunity to investigate other causes of peritoneal MM in this population than asbestos. In the United States and Europe, an increasing number of peritoneal MM do not appear to be associated with asbestos 5, which has led some authors to believe that a subgroup of peritoneal MM may have a different pathogenesis.3 6
In most industrialized countries, pleural MM usually occur in a context of asbestos exposure3,6. Since men are most often involved in the asbestos trades, the incidence of pleural MM is higher in men, with a male / female ratio of about 4: 1.3. Instead, of Chinese patients with 12 pleural MM, 10 of 12 were women (83%, 95% CI, 52% -99%) and only 5 of 12 (42%, 95% CI, 15% -72%). ) had been exposed to asbestos, highlighting the unusual prevalence of MM in Chinese women