Cancer patients' experiences of the diagnosis and treatment of incidental pulmonary embolism (a qualitative study).

BACKGROUND: The diagnosis of symptomatic cancer-associated thrombosis often causes distress and alarm for patients, especially for those unaware of the risk, or the signs and symptoms to look out for. There are few data about cancer patients' experiences of incidentally diagnosed pulmonary embolism (IPE), where lack of warning (recognised signs, symptoms) may cause delayed diagnosis and aggravate distress. OBJECTIVES: To explore cancer patients' experience of the diagnosis of and living with incidental pulmonary embolism treated with anticoagulation. METHODS: A qualitative study using modified grounded theory approach. Semi-structured interviews were conducted as part of a mixed- methods prospective observational survey study of consenting patients with IPE. Data were subjected to thematic analysis. The qualitative findings are presented. FINDINGS: Eleven participants were interviewed (mean age 68.3 years, range 38-82 years; various forms of cancer and stages). Three major themes and one cross-cutting theme were generated. Theme (1): IPE is experienced in the context of cancer and concomitant comorbidities. Issues are understood in the shadow of-and often overshadowed by-current serious illness. Theme (2): Being diagnosed with IPE. Misattribution to cancer or other comorbidities caused delay in help-seeking and diagnosis. Theme (3): Coping with anticoagulation. Participants' incorporated anticoagulation treatment and its effects into their daily routine with acceptance and stoicism. Finally, the cross-cutting theme relates to a lack of information and uncertainty, contributing to distress throughout the experience. CONCLUSION: The diagnosis of IPE was upsetting and unexpected. Expert and timely information was valued by those with IPE. Education called for about the increased risk of cancer-associated thrombosis and the signs and symptoms to be aware of.

Alteration in endothelial permeability occurs in response to the activation of PAR2 by factor Xa but not directly by the TF-factor VIIa complex.

Alterations in the endothelial permeability occur in response to the activation of coagulation mechanisms in order to control clot formation. The activation of the protease activated receptors (PAR) can induce signals that regulate such cellular responses. PAR2 is a target for the coagulation factor Xa (fXa) and tissue factor-factor VIIa (TF-fVIIa) complex. By measuring the permeability of dextran blue across endothelial monolayer, we examined the mechanisms linking coagulation and endothelial permeability. Activation of PAR2 using the agonist peptide (PAR2-AP) resulted in increased permeability across the monolayer and was comparable to that obtained with VEGF at 60 min. Incubation of cells with activated factor Xa (fXa) resulted in an initial decrease in permeability by 30 min, but then significantly increased at 60 min. These responses required fXa activity, and were abrogated by incubation of the cells with a PAR2-blocking antibody (SAM11). Activation of PAR2 alone, or inhibition of PAR1, abrogated the initial reduction in permeability. Additionally, inclusion of Rivaroxaban (0.6 µg/ml) significantly inhibited the response to fXa. Finally, incubation of the endothelial monolayers up to 2 h with TF-containing microvesicles derived from MDA-MB-231 cells, in the presence or absence of fVIIa, did not influence the permeability across the monolayers. In conclusion, fXa but not TF-fVIIa is a noteworthy mediator of endothelial permeability. The rapid initial decrease in permeability requires PAR2 and PAR1 which may act to constrain bleeding. The longer-term response is mediated by PAR2 with increased permeability, presumably to enhance clot formation at the site of damage.

Analysis of the potential of cancer cell lines to release tissue factor-containing microvesicles: correlation with tissue factor and PAR2 expression.

BACKGROUND: Despite the association of cancer-derived circulating tissue factor (TF)-containing microvesicles and hypercoagulable state, correlations with the incidence of thrombosis remain unclear. METHODS: In this study the upregulation of TF release upon activation of various cancer cell lines, and the correlation with TF and PAR2 expression and/or activity was examined. Microvesicle release was induced by PAR2 activation in seventeen cell lines and released microvesicle density, microvesicle-associated TF activity, and phoshpatidylserine-mediated activity were measured. The time-course for TF release was monitored over 90 min in each cell line. In addition, TF mRNA expression, cellular TF protein and cell-surface TF activities were quantified. Moreover, the relative expression of PAR2 mRNA and cellular protein were analysed. Any correlations between the above parameters were examined by determining the Pearson's correlation coefficients. RESULTS: TF release as microvesicles peaked between 30-60 min post-activation in the majority of cell lines tested. The magnitude of the maximal TF release positively correlated with TF mRNA (c = 0.717; p < 0.001) and PAR2 mRNA (c = 0.770; p < 0.001) expressions while the percentage increase correlated with PAR2 mRNA (c = 0.601; p = 0.011) and protein (c = 0.714; p < 0.001). There was only a weak correlation between resting TF release, and microvesicle release. However, TF release in resting cells did not significantly correlate with any of the parameters examined. Furthermore, TF mRNA expression correlated with PAR2 mRNA expression (c = 0.745; p < 0.001). DISCUSSION AND CONCLUSIONS: In conclusion, our data suggest that TF and PAR2 mRNA, and PAR2 protein are better indicators of the ability of cancer cells to release TF and may constitute more accurate predictors of risk of thrombosis.