Deep vein thrombosis is a well-known and common medical problem – approximately 56,000 patients a year in the UK (about 1,000 per week) suffer from DVT. In about 17,000 of these patients, the diagnosis of DVT is only established at post-mortem.
DVT risk factors
The risk factors for DVT are also well known – recent operations on the pelvis or lower limb, prolonged immobility or obesity, previous history of DVT, heavy smoking, certain drugs and a strong family history of DVT are all common risk factors.
What is less widely appreciated is that a spontaneous DVT can also be the first sign of a hidden cancer (so called ‘occult’ cancer in medical language). In other words, a DVT occurring out of the blue in a patient with no obvious other risk factors should start alarm bells ringing for the doctor.
Some cancers produce chemicals in the blood that make the blood more ‘sticky’ and more prone to clotting. These chemicals can cause a DVT or superficial thrombophlebitis in veins in the absence of any other risk factors. People with cancer have an estimated fourfold increased rate of blood clots compared with people who do not have cancer – DVTs in patients suffering with advanced cancer is well known.
The importance of this issue has been recognised in a recently produced guideline (June 2012), relating to the treatment and investigation of cancers by the National Institute for Clinical Excellence (NICE). The guideline is the first of its kind to recommend that investigations for cancer should be carried out in people aged over 40 years who are not already known to have cancer, and who have a blood clot in their leg or lung where there is no obvious cause.
Cancers most likely to trigger DVT
Particular culprits are tumours of the lung and pancreas, but other cancers such as breast cancer can also have the same effect. These hidden cancers can be tricky to diagnose in themselves. Often a CT scan of the abdomen and pelvis is required to find the tumour, especially for organs such as the pancreas, which are deep in the abdomen and impossible to feel on examination or by tests such as ultrasound. In addition, cancers that cause a DVT as a first presentation are often quite small and may be difficult to detect.
Early detection of cancer is the key to effective treatment – if a cancer is diagnosed at an early stage and promptly treated before it has grown or spread to other organs, the success rate in terms of cure and life expectancy is considerably enhanced.
The NICE guidelines recommend a mammogram for women, plus a chest X-ray, blood and urine analysis and a CT scan of the abdomen and pelvis for all patients over 40 years of age presenting with a spontaneous DVT.
Further information on the guideline can be see here : http://www.nice.org.uk/newsroom/pressreleases/VTEDiseasesGuideline.jsp