POST TRAUMATIC CANCER

What evidence is there that trauma causes cancer? Specifically, can a head injury originate a brain tumour?

There is no dispute that carcinoma may arise as a result of persistent or recurrent mechanical or chemical irritation, or of longstanding infection, typically chronic osteomyelitis. An increased liability to malignant melanoma at the site of blistering sunburn is similarly well recognised. There is, however, no precedent for causation of malignant disease by a single mechanical traumatic injury, however severe.

PRACTICE POINT There is no known pathogenetic mechanism where a physically traumatic event might cause cancer.

18 years ago a team at the Mayo Clinic followed[1] nearly 3000 head-injured patients for an average of 10 years to identify subsequent development of brain tumour. Such cancers are sufficiently rare that it was not possible to achieve a high level of statistical certainty, even with a study of this magnitude. Nevertheless they found no evidence for a causal relationship. They pointed out that meningioma, the commonest type of brain tumour, is more common in women, whereas head injuries are two to three times commoner in men.

Proposed cases have been reported in the medical research literature sporadically. In one 1995 case from Poland, a meningioma developed at the site of a skull incision for brain surgery 28 years previously[2]. In another from Germany a pregnant woman was found dead, probably from a seizure caused by a 4 cm meningioma at the location of a severe head injury 5 months previously[3].

As previously noted (Medical Litigation News Volume 2, Issue 3), most cancers are at least 5 years old before they can be diagnosed, and it takes about 30 doublings of a single cell to produce a 1 cm diameter mass.

The Volume-Doubling Time[3a] of meningioma is of the order of 5 months to 3 years, generally about 10 months[4]. Thus, the timing of the Polish case at least makes biological sense, whereas it was easy in the German case to refute a causal connection. By the same token, the Mayo Clinic study could usefully be updated to detect an effect after 30 years.

PRACTICE POINT The growth of brain tumours takes years if not decades.

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