Thromboembolism rate lower than expected in Chinese patients with pancreatic cancer

Chinese patients with pancreatic cancer have a lower incidence of thromboembolism compared with Western populations, and thromboembolism does not affect overall survival (OS), researchers from the Chinese University of Hong Kong (CUHK) have reported.  

“Patients with pancreatic cancer have a high risk of thromboembolism, which may increase mortality risk,” wrote the researchers. “As most relevant studies are conducted in Western populations, its incidence rate and effects on OS remain unclear in Chinese populations.”

The researchers recruited 365 patients with exocrine pancreatic cancer (median age, 65 years; male, 59.5 percent; stage I─III, 46.8 percent; Chinese, >99 percent) treated at Prince of Wales Hospital (PWH) in Hong Kong between 2010 and 2015 into a retrospective cohort study. [Hong Kong Med J 2023;29:396-403]

A total of 54 patients (14.8 percent) developed thromboembolism, with lower limbs being the most common sites. “The overall incidence of thromboembolism in Chinese patients with pancreatic cancer was similar to that reported in other studies of Asian populations [Japan, 7.2 percent; Taiwan, 8.0 percent; Korea, 18.6 percent], but lower than that in most Western populations [France, 20.8 percent; Germany, 41.3 percent],” the researchers reported.

Consistent with findings from other studies of Asian populations, median OS did not significantly differ between patients with or without thromboembolism (4.88 months vs 7.8 months; hazard ratio [HR], 1.08; 95 percent confidence interval [CI], 0.80─1.49; p=0.58) and between patients with thromboembolism who received or did not receive anticoagulants (5.63 months vs 4.77 months; HR, 0.72; 95 percent CI, 0.40─1.29; p=0.27).

In contrast, in Western patients with pancreatic cancer, OS appeared to be inherently longer and was affected by thromboembolism and its treatment. [Hong Kong Med J 2023;29:396-403; Gastroenterology 2020;158:1346-58.e4; Thromb Res 2017;157:9-15; Cancers (Basel) 2018;10:501; Clin Appl Thromb Hemost 2021;27:10760296211051766; Blood Res 2018;53:227-32; Hepatobiliary Pancreat Dis Int 2015;14:436-42]

“Our findings support the hypothesis that thromboembolism incidence and outcomes are influenced by genetic and environmental differences between Western and Asian populations,” noted the researchers. “Considering the aggressive nature of pancreatic cancer, it is possible that patients with shorter OS [eg, Asian patients] did not live long enough to benefit from anticoagulants, whereas patients with longer OS [eg, Western patients] experienced survival benefit from treatment of thromboembolism.”

In a multivariable logistic regression analysis, stage IV disease was a significant risk factor for thromboembolism (odds ratio, 1.08; 95 percent CI, 1.00─1.17; p=0.046). The underlying pathophysiological mechanisms involve the mass effect of bulky metastases and tumour burden, which can compress blood vessels and restrict blood flow.

“Given the poor prognosis of pancreatic cancer and the lack of an OS benefit associated with thromboembolism treatment, factors such as quality of life should be considered when deciding whether to initiate or discontinue anticoagulants [in Chinese patients with pancreatic cancer],” suggested the researchers. “It is important to have clear discussions with patients regarding the risks and benefits of anticoagulation treatment, particularly during management of stage IV pancreatic cancer, where life expectancy is often only months or weeks.”