The UK's biggest charity has drawn up a shortlist of four undisclosed agencies to pitch for the business. WWAV Rapp Collins, the incumbent on Cancer Research UK's fundraising activity, has not been invited to present.
The brief is to develop appeals using direct mail targeting mid-value donors - people who give more than £2 a month, but do not make large, one-off donations.
Cancer Research UK is said to be looking at new ways of increasing donations in the face of competition from international disasters such as the Asian tsunami.
Cancer Research UK splits its business between a number of agencies.
Ogilvy & Mather handles its advertising while OgilvyOne handles customer acquisition. Bartle Bogle Hegarty was appointed in 2003 to develop an anti-smoking campaign.
A spokesman for Cancer Research UK confirmed a DM pitch was taking place.
However, he added that it had no bearing on the rest of the work that WWAV does.
In a statement, the charity said: "Cancer Research UK is not seeking to replace WWAV Rapp Collins as one of its main agencies and is, in fact, increasing the scope of its work for the charity.
"It has provided the creative for a new project within the fundraising and marketing department. Now this project is being rolled out, we have decided to ask other agencies to pitch for this one project.
"Cancer Research UK is delighted to be continuing to work with WWAV on its direct marketing programmes."