The success of the HPV vaccine has been widely talked about and rightly celebrated, but it only works if it is administered before a person is infected with the human papillomavirus. 

That is great news for the millions of girls worldwide who have received the jab over the last decade or so. It is not such good news for those who were "above age" during its rollout or were already carrying the cancer-causing strains of HPV before inoculation. 

Excitingly, a new immune-based therapy targeted at precancerous lesions in women with the virus has been tested and shows promise. Indeed, HPV was completely cleared in one-third of cervical cancer precursors post-treatment, a study recently published in the journal Gynecologic Oncology found.

It's true that it doesn't pass the halfway mark, but it does outperform current methods by quite some distance.

The standard treatment for precancerous lesions involves removing a cone-shaped section of the cervix. Not only does this result in scarring and a shortened cervix, but it also leaves traces of HPV – the very thing that caused the lesions to develop in the first place. This puts patients at high risk of developing cervical cancer later on. 

"The surgical procedure removes all the tissue that is headed towards cancer, but it doesn't remove all the HPV. You're not home-free. You still have HPV," Diane Harper, a professor of family medicine and obstetrics and gynecology at the University of Michigan, said in a statement. 

So, how does this new treatment work? It involves a vaccine that contains a protein that prompts immune cells to attack the strains of HPV responsible for causing cervical cancer precursors called cervical intraepithelial neoplasia (CIN). 

CINs can be grouped into three categories based on severity, with CIN 1 lesions the very least serious, often clearing up of their own accord. For the study, researchers recruited 192 women with CIN 2 and CIN 3 lesions. The latter is the most severe and even then, fewer than half of those with a CIN 3 lesion will go on to develop cancer within 30 years. Like CIN 1, CIN 2 tend to clear up on their own, but they do sometimes progress to CIN 3. 

The therapy – involving three shots in the thigh once a week for three weeks – were administered to 129 women. The remaining 63 were given a placebo. Six months later, the women underwent surgery to have the tissues removed and examined. 

The results suggest that those who were given the vaccine were more than two times as likely to have their CIN lesion eliminated. This includes 15 to 36 percent of those in the vaccine group with CIN 3 lesions. In contrast, no one in the placebo group with CIN 3 saw theirs eliminated. 

While the therapy is still, currently, in the experimental stage and the vaccine will need to pass further clinical trial before it can be approved by the US Food and Drug Administration, it's exciting news.

"There are very few products trying to cure women who already have an HPV infection," Harper added. "This is the first time we've seen something with this success rate that is relatively easy to implement."