Polio Vaccine & Cancer - Unintended Consequences

The elimination of polio in the Americas was undoubtedly a good thing.  However, it did not come without cost.  The Oral Polio Vaccine (OPV) that was given between the years of 1955 and 1963 was contaminated by a virus called Simian Virus 40 (SV40).  SV40 has been linked to rare, incurable cancers such as ependymomas (brain tumors), mesotheliomas (pleural tumors, usually of the lung), and osteosarcomas (bone malignancies).  See more here:

http://www.projectcensored.org/top-stories/articles/12-millions-of-americans-received-contaminated-polio-vaccine-between-1955-and-1963/

Was this a reasonable price to pay to eliminate polio?

Was it a necessary price to pay?  That is, could we have eliminated polio without also spreading SV40?

Is this the law of unintended consequences at work?  Or was this carelessness?  

When is it a wiser choice to wait for better science, and when are the known problems so severe that it's better to charge forward with imperfect technology?  

What do you think?  Add your comments.

Please note!!!  The vaccine detailed in this story has not been used in the United States for 50 years.  The vaccine currently in use in the United States is the IPV.  Unlike the OPV, it is completely dead.  The IPV cannot spread live viruses of any kind.