http://www.hindawi.com/journals/isrn/2013/109846/ >Consequently, the prevention of sexually transmitted infections cannot rationally be interpreted as a benefit of circumcision, and any policy of circumcision for the general population to prevent sexually transmitted infections is not supported by the evidence in the medical literature.
study from 1999 >A meta-analysis was performed on the 29 published articles where data were available. When the raw data are combined, a man with a circumcised penis is at greater risk of acquiring and transmitting HIV than a man with a non-circumcised penis (odds ratio (OR)=1.06, 95% confidence interval (CI)=1.01-1.12).
I'm no expert on this and I'm not going to look for any more studies now. Off the top of my head, I would guess that the idea behind it helping "reduce risk" for penile cancer is that they are removing a part of the foreskin on the penis. This means that a little portion can no longer become cancerous?
As to UTIs, I think issues with hygiene in uncircumcised people can be a large confounding variable in studies. It's like learning to clean behind your ears.
Also found this gem of stupidity, just read the bold and you'll see. >Circumcision of males represents a "surgical vaccine" against a wide variety of infections, adverse medical conditions and potentially fatal diseases over their lifetime, and also protects their sexual partners. In experienced hands, this common, inexpensive, simple procedure is very safe, and can be pain-free. Although it can be performed at any age, the ideal time is infancy. The benefits vastly outweigh risks.
>The public health benefits are enormous, and include protection from urinary tract infections, that are common over the lifetime and often cause permanent kidney damage in babies, inferior genital hygiene, smegma, sexually transmitted HIV, oncogenic types of human papillomavirus, genital herpes, syphilis and chancroid, penile cancer, and possibly prostate cancer, phimosis, paraphimosis, thrush, and inflammatory skin conditions such as balanitis and balanoposthitis. In women circumcision of the male partner provides substantial protection from cervical cancer, genital herpes, bacterial vaginosis (formerly termed "gardnerella"), possibly Chlamydia (that can cause pelvic inflammatory disease, infertility, and ectopic pregnancy), and other infections.
>Circumcision has socio-sexual benefits and reduces sexual problems with age and diabetes. It has no adverse effect on penile sensitivity, erectile function, or sensation during sexual arousal and is reported to enhance the sexual experience for men. Most women prefer the circumcised penis for appearance, hygiene, lower infection risk and sexual activity. At least half of all uncircumcised males will develop one or more problems over their lifetime caused by their foreskin, and many will suffer and die as a result. The benefits exceed the risks by over 100 to 1, and if the level of suffering and fatalities are taken into account in men and their sexual partners the benefit is orders of magnitude higher than this. Given the convincing epidemiological evidence and biological support, routine circumcision should be highly recommended by all health professionals and access facilitated by the health systems of every country.