Making connections – from birthmarks to cancer therapy.

The ability to advance medicine by making connections between seemingly unrelated observations is the mark of a gifted scientist. Wellington plastic surgeon Professor Swee Tan and his team are embarking on a Genesis Oncology Trust-funded project based on such a connection.

Dr Tan is already internationally known for his work in the cause and treatment of strawberry birthmarks (haemangioma), and his careful research into these benign childhood tumours leaves him poised to make an even greater contribution to the field of cancer therapy.

Haemangiomas are the result of abnormal growth of blood vessels, and usually disappear in time. But sometimes they need to be treated because of their location.

Dr Tan and his team have discovered that strawberry birthmarks are caused by stem cells, which are regulated by the reninangiotensin system involved in the control of blood pressure. This forms the basis of treatment with common blood pressure lowering drugs that make haemangiomas shrink and disappear without surgery.

Early French trials used beta blockers like Propanadol, which are effective, but do have side effects. Dr Tan and his team have pioneered the use of the ACE-inhibitor Captopril, an equally effective blood pressure drug, which has fewer side effects.

So, how is this related to cancer? The answer lies in solid tumours’ need for an ever-increasing blood supply as they grow. This requires the development of new blood vessels, a process known as angiogenesis.

Using drugs to treat cancer by inhibiting angiogenesis is a fertile field of cancer research. Dr Tan and his team noticed that the abnormal blood vessels of haemangiomas and those of some head and neck cancers share many common features. They reasoned that the same blood pressure lowering drugs that were effective in birthmark trials may be effective anti-cancer drugs.

Says Dr Tan, “Careful laboratory studies are first required, and the Genesis Oncology Trust grant will be used to confirm the involvement of the renin-angiotensin system in angiogenesis, and to see if the blood pressure drugs can inhibit blood vessel growth in cultured tumour tissue. If successful, the laboratory work may lead to trials in humans, and we will be one step closer to a cure for cancer.”

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