This archaic word originally referred to a disease in the mouth, painful and erosive. Today it has more of a symbolic meaning. I have heard it used in English as "canker", "canker sore" or "curse". The dictionary definition that is applicable here is "an erosive or spreading sore".

An example from a recent essay written in English:
"Global warming is like a canker sore. We create it and at first we just ignore it, and go on with our daily lives. ..."

Two other examples, from translations:
"'Egy rákfene,'' ahogy ő nevezte." - ''A canker,'' as he put it.
"Ezenkívül azt sem lehet tagadni, hogy a klasszikus írók hatása a legnagyobb mértékben erkölcsképző, ugyanakkor, amikor a természettudományok oktatásával szerencsétlenségünkre együtt járnak azok a kártékony és hazug tanok, amelyek korunk rákfenéi" -
"Moreover, it cannot be denied that the influence of the classical authors is in the highest degree moral, while, unfortunately, with the study of the natural sciences are associated the false and noxious doctrines which are the curse of our day."

Az alább hivatkozás szerint finnugor eredetű: "szájüreg betegsége: fene, rákfene" - which is what we call a "canker sore" in English.
http://adattar.vmmi.org/folyoiratszamok/157/letunk_2009.03.p...

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Note added at 32 mins (2011-04-07 17:50:13 GMT)
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To be precise, RÁK is CANCER, FENE is CANKER, so RÁKFENE could be either, based on the context. In this particular instance I would use the milder "canker" as the consumer society is unlikely to be fatal to the the planet, it is only erosive and spreads like a 'canker sore'... (See for example: Alan Durning, "How Much is Enough: The Consumer Society and the Future of the Earth")

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Note added at 36 mins (2011-04-07 17:53:54 GMT)
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Hasonló példa, a rasszizmus terjedése kapcsán:
"... we were equally blind as to how the canker-sore of racism at home would rear. The newly-radicalized conservatives, who used the name “Hussein” as their coded rallying cry, warred against the 60s-radicals-of-yore, who saw in candidate Obama the chance to at last perfect unfulfilled dreams of true equality, in bouquets that would scent the streets as completely as boardrooms, across America."