A worrying spectre
The WHO is sounding the alarm bell, forecasting that one American in five and one Australian in two will develop some form of skin cancer during their lifetime. Europeans are not spared either. They have a one in 33 chance of developing melanoma, the most aggressive skin cancer of all.
In Western societies, the ideal of the beauty of tanned skin is probably the biggest culprit in the worrying increase in skin cancers. Without excluding other still poorly known causes, researchers insist that regular, prolonged exposure to ultraviolet (UV) rays, both natural and artificial, ages the skin prematurely and encourages the appearance of cancerous tumours.
Melanoma, the primary image people associate with skin cancer, in fact represents just 10 % of skin cancers. The most widespread cancer is basal cell carcinoma, which alone accounts for 70 % of all skin cancer cases. Outwardly similar, but much more dangerous is spinocellular carcinoma, which represents 10 % of skin cancer diagnoses. The remaining 10 % corresponds to other relatively rare skin cancers.
Children are at most risk. With their delicate skin, even short exposure is enough to produce serious burns. Studies are also beginning to show that the mutagenic effects of UV rays are accumulated during childhood, which means that simple sunburns can provide the foundations for a high degree of melanomas in later life.
Once a skin cancer has been diagnosed, treatment always begins with the surgical ablation of the cancerous tissue. If the excision is large and the wound is unable to close naturally, a skin graft is carried out. Avoiding any propagation of the cancer may also require the removal of possibly affected drainage ganglions.
But even with these measures, the risk of recurrence of melanoma remains 50%. Parallel to this, radiotherapy can partially or totally destroy the malignant cells, which are less resistant than healthy ones to ionizing radiation.
In cases where the cancer has metastasised, chemotherapy seeks to remove the sickness with medication. The compounds administered in this way directly attack the cells that are multiplying at an abnormally high speed, which is the primary characteristic of cancer cells. The secondary effects are far from negligible, as all organs of the body are affected via the blood stream. To resolve this problem, in the rare cases where the cancerous lesions are located on a single limb, the blood circulation can be isolated by garrotting the limb and using a pump to limit dissemination of these cytostatic compounds.
Very early detection of cancer means less heavy treatment and greater chances of recovery.
Researchers are therefore examining new diagnostic techniques that are more effective and less invasive. "This is precisely the aim of the European Skinspection consortium," explains Robert Lemor, project coordinator and head of the ultrasound department at the Fraunhofer Institute for Biomedical Technology (DE). "By combining optical and acoustic imaging technologies, we hope to be able to offer dermatologists and surgeons a new tool for high resolution 3D imaging of the skin section being analysed. This would permit precise, early diagnosis and monitoring of the therapeutic effects of the treatment." The project, initiated in March 2008, is currently in the protocol definition and experiment timetabling stage. But Robert Lemor is already optimistic about the outcome: "This innovative technology should significantly reduce the number of unnecessary excisions, including the ablation of ganglions. The non- invasive aspect reduces the psychological and aesthetic impact on patients. It will also be easier to monitor treatments over time. In the longer term, we are also hoping to limit therapy costs and especially reduce skin cancer mortality levels."
Vaccines: a promising avenue
Vaccination of skin cancer patients is a new and interesting line of research. "Our project aims to direct the patient's immune system against its own cancerous cells. Therapeutic vaccination would supplement traditional methods for eliminating residual cancerous tissues and could impose itself as a treatment in its own right," explains immunologist Pierre Coulie from the Institut de Duve of the Université Catholique de Louvain (BE), which is taking part in the European Cancerimmunotherapy project. "Therapeutic vaccination is promising.
Numerous clinical tests over the past ten or so years have demonstrated its effectiveness on certain patients. Five per cent of all vaccinated melanoma carriers present a regression of the metastases. This percentage is still low, but the treatment is without secondary effects, which is rare in cancer therapies. Researchers are therefore trying to understand why the treatment works for certain patients and not for others, in order to come up with more effective vaccines. "There are several interesting avenues linked to the ability of certain tumours to locally inhibit the effectiveness of the immune system. But we are still at an exploratory phase and a lot of fundamental research still has to be done before we see these therapies on the market."