The article is correct, however the science is not accurate in saying that anal cancer is caused by fusion of sperm with other cells. I can't understand why the author used a 30 year old study.
The most probable cause of anal cancer is Human Papilloma Virus, just as HPV causes 99.7% of all cervical cancer. The connection wasn't known in 1977.
http://www3.interscience.wiley.com/cgi-bin/abstract/109061862/ABSTRACT
http://www.cmaj.ca/cgi/content/full/169/5/431
http://www.ncbi.nlm.nih.gov/entrez/utils/lofref.fcgi?PrId=3051&uid=12639077&db=pubmed&url=http://www.annals.org/cgi/pmidlookup?view=full&pmid=12639077
The common denominator between these two diseases is the sharing of disease - if virgins married virgins and there were no sex outside of marriage, these diseases would be very, very rare.