Norwegians lead the world in instances of malignant melanomas. But they are now being surpassed by the Swedes in cases of an aggressive type of skin cancer – Merkel cell carcinoma. (Photo: Science Photo Library)

Rare aggressive skin cancer on the rise

Cases of the aggressive skin cancer Merkel cell carcinoma (MCC) have nearly doubled in the past 20 years in Sweden.

The cancer type is still rare. In the past two decades 594 patients were diagnosed with MCC in Sweden.

But health authorities have reason to be concerned as Swedish researchers find a significant increase in cases of this cancer. 

The number of cases per 100,000 capita increased by 100 percent from 1993 to 2012.

This type of skin cancer has a very high mortality rate.

A third of all who contracted this cancer were dead after five years, according to a study at the University of Gothenburg’s Sahlgrenska Academy.

Too much sunning

Over half of these cases of the cancer developed in the head and neck region of the patients.

“This indicates that the Sun’s UV rays have a big impact on the diagnosis,” says Oscar Zaar, a dermatologist and Research Fellow at Sahlgrenska Academy in a University of Gothenburg press release.

Five to ten cases a year in Norway

The Sahlgrenska researchers have studied all the instances of this aggressive cancer form reported in Sweden from 1993 to 2012.

An average of 23 new cases was reported per year from 1993 to 2001. From 2002 to 2011 the frequency rose to an average of 34 new instances per year. In 2012 the number of new cases in Sweden was 47.

Norway has about half the population of Sweden and instances of MCC are presently reported to be about five to ten per year. Women are diagnosed with the disease a little more often than men, according to Trude Eid Robsahm, a researcher at the Cancer Registry of Norway.

By comparison, about 2,000 persons in Norway get malignant melanomas annually.

Small increase in Norway

“We can see a tendency toward a slight increase of Merkel cell carcinoma in Norway too the past few years, but only among women. It would be premature to say whether this is a trend or just a matter of year-to-year variations,” she says.

Robsahm has no clear explanation for why the occurrences of this type of cancer are more frequent in Sweden than in neighbouring Norway.

Generally have more skin cancer

On the whole, however, Norwegians are more prone to get skin cancer than Swedes are. Norwegians top Swedes in frequency of melanomas and other skin cancer types.

“We don’t have an answer for this either. It could be because Swedes are better at adhering to advice on tanning and exposure to the sun. Another explanation is that they have a proportionately larger

immigrant population, which is less prone to contracting skin cancer,” she says.

Virus in the skin

Norwegian and Swedish researchers have earlier cooperated on a joint study of Merkel cell carcinoma.

They found a connection between the cancer type and a virus which is rather common in human skin – Merkel cell polyomavirus.

Translated by: Glenn Ostling

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