Trial Information

Trousseau Studie, Mortaliteit Door Maligniteit Bij patiënten Met Idiopatische Veneuze Tromboembolie

Study design:

Although a randomized design is ideal for most studies we preferred a multicenter,
prospective concurrently controlled cohort study design for our study. This is based on the
experiences with the SOMIT study, in which two of the members of the executive committee (MH
Prins, JMMB Otten) were involved.

The SOMIT study originally was supposed to have been conducted in eight countries. Medical
ethical committees in most countries however considered it unethical to conduct this
randomized study. Either because of the fact that the study contained a control arm, or
because the screening arm (and thus the study itself) was considered to be unethical.

Patients as well as physicians found it difficult to let fate decide whether or not a
patient would be screened for cancer, even though it was not clear if screening was
life-saving. Moreover, during the SOMIT study, physicians noticed that patients with IVTE
had their cancer detected early if they were in the screening group. This made it even more
difficult to withhold additional screening procedures in patients in the routine group.

Many physicians themselves showed a strong preference for one of the arms of the study.
Therefore they did not include as many patients as they could.

With a prospective cohort design we expect to avoid these problems. Per hospital that
participates in the Trousseau study the physicians in that hospital will treat the patients
according to the local preference for screening or no screening. All hospitals are matched
regarding their population as much as possible.

Statistics:

The prevalence of occult cancer at the time of the thrombotic episode in patients with IVTE
can be estimated to be 10%. Based on the nature and stage of malignancies, it is expected
that half of these patients with occult malignant disease will die during the 3 years of
follow-up, resulting in a cancer-related mortality of 5%. In addition, in approximately half
of the patients with malignant disease who survived for 3 years, residual or recurrent
cancer will be present. Therefore, cancer-related mortality or residual or recurrent cancer
will be present in 75% of the patients with occult malignant disease at presentation, i.e.,
in 7-8% of the patients of the study cohort. We anticipate that approximately 80% of the
occult malignancies will be detected by extensive screening and that early treatment will
result in a 50% to 75% reduction of the 3-year incidence of cancer-related mortality or
residual or recurrent malignancy.