Cancer treatment has made great progress in recent decades, but the tragedy is that so much of our effort to combat this scourge is just that: treatment. Once a disease appears, there is only so much that can be done. It would be far cheaper, more effective and less traumatic to prevent it.A vaccine for cancer would be a triumph for public health. Did I say “would be”? Actually, it is. Such a vaccine exists for one of the biggest killers of women. But Rep. Michele Bachmann, R-Minn., is against it, and she's not alone.Two different vaccines block transmission of the human papillomavirus (HPV), which causes 70 percent of all cervical cancer in this country, as well as most anal cancers and some cancers of the throat, vagina and penis.Each year, says the National Cancer Institute, more than 12,000 American women are diagnosed with cervical cancer alone, and some 4,000 will die of it. That's not counting the genital warts HPV can cause.It's a nasty but very common bug that the world would be better off without. Universal inoculation would be a huge step toward eradicating it and the suffering it causes.But there is a big impediment to its use: HPV is sexually transmitted, which makes the vaccine controversial -- especially because to achieve maximum effectiveness, it has to be administered before the recipient becomes sexually active. And in this country, 6 percent of youngsters have sex by the age of 13.So the federal Advisory Committee on Immunization Practices recommends that females get the vaccine no later than age 12. As governor of Texas, Rick Perry required that girls be immunized.He defended then the mandate as “responsible health and fiscal policy that has the potential to significantly reduce cases of cervical cancer and mitigate future medical costs.” Bad for cancer, boon for the budget. What's not to like? But Perry has retreated under attack from fellow conservatives.One allegation is that he made the decision to repay drug maker Merck, a longtime campaign contributor. That might explain his unusual willingness to mandate the vaccine even though public health groups were not in favor of compulsion.But Bachmann also accuses him of heartless cruelty. “To have innocent 12-year-old girls be forced to have a government injection through an executive order is just flat-out wrong,” Bachmann said.Oh? Children are routinely subjected to “government injections” when they get compulsory inoculations for polio, diphtheria, measles and other illnesses. Most states require kids to be immunized against hepatitis B, which is commonly contracted sexually. What's cruel about being protected from cancer?Bachmann insists the vaccine is “a very dangerous drug.” After the debate, she reported, she met a woman whose daughter developed mental retardation in reaction to the shot.Would she believe someone who told her the vaccine came from space aliens? The head of the American Academy of Pediatrics, made up of physicians who devote their lives to protecting innocent children, said of Bachmann's claim, “There is absolutely no scientific validity to this statement.” It notes that the vaccine has “an excellent safety record.”Social conservatives also fear that the inoculation condones and encourages adolescent sex. But if the danger of pregnancy, AIDS and other diseases is not enough to deter a teenager, we can assume HPV will not be a deal-breaker.Bachmann and others detest the mandate as an invasion of parental rights. But we don't leave it to parents to decide whether to inoculate against other diseases. We require immunization to protect children (and everyone else) from the consequences of bad parental choices. As early as 1905, the Supreme Court has rejected the notion that anyone has a constitutional right not to be vaccinated.Parents are entitled to preach, demand and enforce chastity for their children. But if a child spurns that option, the penalty should not be a deadly, avoidable disease. Besides, even abstinent youngsters can be infected -- through sexual assault.The mandate is hardly beyond criticism. When Perry signed his order, I faulted him for taking the compulsory approach, not because it was an outrageous violation of liberty, but because voluntary efforts had not been given time to succeed and the mandate might provoke resistance. That fear turned out to be accurate, but it doesn't make him a Big Government bully.Perry was overzealous in combating a real danger. Bachmann is overzealous in hyping phony ones.