A Killer Blow to Cervical Cancer?
The widespread implementation of routine screening for cervical cancer via the Papanicolaou (Pap) smear test has caused a significant drop in the incidence of cervical cancer in the western world. However, cervical cancer remains the second most common cancer in women the world over, and a leading cause of cancer-related death in the developing world. But according to a new report by independent market analyst Datamonitor (DTM.L), two new vaccines for the human papilloma virus (HPV), a major risk factor for cervical cancer, are set to have a dramatic impact on the incidence of cervical cancer all over the globe.
Two Worlds, Two Different Situations
Routine screening with the Pap smear test allows for early detection of pre-invasive lesions and as a result, cervical cancer now accounts for only 17% of all gynecological malignancies in the western world. In developing countries however, due to the poor access to medical care, a lack of healthcare infrastructure and the absence of routine screening programs, cervical cancer remains a very significant problem- which provides further evidence of the significant impact this screening has had in developed countries.
Women suffering from HPV infection have a 50- to 100-fold greater risk of developing cervical cancer. More than 80 types of HPV have been identified, with subtypes 16 and 18 most commonly linked to cervical cancer- present in approximately 90% of invasive tumors (1). Significant progress has recently been made with the development of two vaccines to prevent HPV infection and subsequent cervical cancer: Merck & Co’s Gardasil and GlaxoSmithKline’s (GSK) Cervarix. Gardasil became the first vaccine FDA and EMEA- approved for this indication, in June 2006 and in September 2006, respectively. Cervarix is currently in preregistration in the EU and an NDA submission is expected this month.
Both vaccines represent a major healthcare breakthrough, capable of significantly reducing the human and economic burden of cervical cancer by drastically reducing its incidence, says Datamonitor senior oncology analyst Fleur Pijpers. “According to studies, widespread use of the vaccines in the U.S. alone has the potential to avoid $6.3 billion in treatment costs per year. However, the full impact of the vaccines will not be felt unless their provision to women in developing countries is ensured.”
With a $27.8 million grant from the Bill & Melinda Gates Foundation, Merck and GSK will work alongside the Program for Appropriate Technology in Health (PATH) to accelerate and facilitate the availability of the vaccines to the developing world. In addition, Merck has announced its intention to make Gardasil available in developing countries at dramatically lower prices than the average wholesale price in the U.S. of $450 for a three-dose course of the vaccine (2), Pijpers says.
“By virtually eliminating HPV-related infection, the incidence of cervical cancer will significantly decrease, particularly if the vaccines are made available in developing countries, where a lack of screening means the disease is still rife.”
“Ultimate success of the vaccination programs remains to be seen, however, given that several issues have arisen, including with regards to the precise population that requires vaccination,” she says.
Just for Girls?
Key opinion leaders interviewed by Datamonitor expressed some concern that despite the HPV vaccines “profound impact”, the vaccination program was only going to include girls. As males are also carriers of the virus, the sort of immunity required to completely prevent HPV is unlikely to be achieved by vaccinating only females. The nature of disease the vaccines are protecting against is also likely to raise an issue among some groups, Pijpers says. “Opinion leaders expressed concern that some parents may decline to have their children vaccinated because they believe it will promote sexual promiscuity.”
However, one negative impact that the HPV vaccines may actually have is on national screening programs, which could have significant repercussions. It must also be noted that Gardasil and Cervarix only confer protection against a finite number of HPV strains, which is of significance, given than more than 80 subtypes have been identified, Pijpers says. “The vaccination may well make people somewhat blasé about screening and we may see a reduction in the uptake of screening. So its possible we may see a partial increase in the incidence because of that,” she says.
“Some sort of change in the dynamics of the disease is also possible, and we may find an increasing predominance of cancers related to the other high-risk subtypes, like 31, 33, and 45.”
However, it is also thought possible that regionalized vaccines will develop in the future to deal with regionalized strains, much as there is with influenza vaccines.
A lack of clinical data regarding the length of time the vaccine is effective for is also a potential problem. However, while these issues may pour some water of the fire of optimism surrounding Gardasil and Cervarix, they should not detract too much from what is a major breakthrough in the treatment of cervical cancer, Pijpers says. “While there are some unanswered questions going forward, it is difficult not to get excited about the potential of Gardasil and Cervarix to save both lives and money in both the developed and developing world.”
