FREE TESTS: Female sanitation workers in Guangzhou, Guangdong Province, wait in a hospital to receive a free cervical cancer screening on March 8, 2013 (LU HANXIN)

Cancer kills, but some cancers have become avoidable due to the latest development of vaccines against certain viral infections. Cervical cancer, the third most common cancer in women, is one such preventable cancer.

Virtually all cervical cancer cases are linked to infections caused by the human papillomavirus (HPV). As early as in the 1990s, research established a consistent association between HPV and cervical cancer. In 2006, the U.S. Food and Drug Administration approved the first preventative HPV vaccine. However, though several HPV vaccines have been approved in more than 140 countries and regions, they are still unavailable on the Chinese mainland, where around 80,000 women died from cervical cancer and 150,000 new cases were diagnosed last year.

Cervical cancer was little known on the Chinese mainland until the untimely death of Hong Kong Cantopop icon Anita Mui Yim Fong at the age of 40 at the hands of the disease in December 2003. Young female mainlanders who want the vaccination, most of them well-educated and well-off, typically go to Hong Kong or Macao, where HPV vaccines are available.

There is no annual figure of women from the Chinese mainland receiving vaccination in Hong Kong, but their increasing popularity can be seen through a number of foolproof guides on the Internet.

Prolonged review

HPV infections are very common, but usually go away on their own. However, persistent HPV infections can cause cellular abnormalities that could develop into cervical cancer if not treated. Two HPV vaccines are currently on the market, Gardasil and Cervarix. Both of them protect against HPV-16 and HPV-18, which are responsible for about 70 percent of cervical cancer cases.

"The two HPV vaccines should be introduced as part of a coordinated strategy to prevent cervical cancer and other HPV-related ailments," according to the WHO's HPV vaccine position paper published in April 2009. At present, many developed countries have integrated HPV vaccines into their national immunization programs and provide them free of charge to adolescents. Furthermore, HPV vaccines have been licensed in numerous developing countries, such as Mexico and Kenya.

However, vaccines made by two multinational pharmaceutical companies—the UK-based Glaxo Smith Kline Biologicals and the U.S.-based Merck—are still undergoing regulatory review and as a result they have not been approved for use on the Chinese mainland.

According to China's regulations on drug registration, which went into effect on October 1, 2007, all overseas producers of vaccines must perform a local clinical trial. Since the original global clinical trials for HPV vaccines recommended by the WHO did not include China's mainland, delays in vaccine availability are unavoidable.

Moreover, the regulations require evaluating efficacy of candidate HPV vaccines against moderate to severe cervical pre-cancer, which requires a control group in the trials to be administered a placebo instead of the vaccination. The China Food and Drug Administration (CFDA), the national drug regulator, insists on approving the vaccines only after enough people among the placebo control group develop cervical cancer or grade II cervical interstitial neoplasia.

However, many countries, such as India and Japan, have followed a suggestion of the WHO in evaluating persistent HPV infections rather than pre-cancerous diseases as a surrogate endpoint as the time between the initial HPV infection and development of cervical cancer is usually decades.

In China, many gynecologists and epidemiologists have called for the regulatory authority to follow suit and expedite the approval process.

Liu Jihong, the chief cervical cancer specialist at Guangzhou-based Sun Yat-sen University Cancer Center in south China's Guangdong Province, told newspaper Southern Weekly that her facility treats more than 1,000 cervical cancer patients every year, which is equivalent to the total new cases diagnosed in Australia in the same period. Sometimes, she has to perform three operations on patients with cervical cancer in a single day.

The cancer center Liu works for is one of the four medical facilities participating in the clinical trials of HPV vaccines in China, which started in 2009.

When Liu's team submitted the Phase III trial efficacy data on Gardasil to the CFDA's predecessor, then known as the State Food and Drug Administration (SFDA), in 2012, the agency ruled that too few cases of grade II cervical interstitial neoplasia had rendered the presentation as insufficient. The presentation used a composite index combining persistent HPV infections with grade II cervical interstitial neoplasia. The SFDA required Liu's center to extend the trial to gather more data.

Liu admitted that this was a daunting task, even after she and her colleagues increased the frequency of trial participants' visits to once every three months.