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AsianScientist (February 18, 2019) – A research group in Japan has found that cervical cancer rates have increased in recent years due to low cancer screening and stopping vaccination against human papillomavirus (HPV) recommended by the government. They published their findings in the journal Research against cancer.
Two strains of HPV account for more than 70% of all cases of cervical cancer. Fortunately, there are HPV vaccines that have demonstrated their ability to dramatically reduce the occurrence of cervical cancer. Coupled with early detection techniques such as Pap smear, cervical cancer is a largely preventable and treatable disease.
However, the incidence of cervical cancer has increased in Japan, said researchers led by Professor Yutaka Ueda of the University of Osaka in Japan, who reviewed data from 1976 to 2012 comprising more than 50,000 cases of cervical cancer and related relatives extracted from the Osaka Cancer Registry.
"The Osaka Cancer Registry gives us particularly useful information about cancer trends because it is a large and well-recorded cohort," said Ueda. "Osaka prefecture accounts for about 10% of Japan's population, so the data is fairly representative of the country."
The researchers retroactively categorized cases by stage, age group, diagnosis period and histological type using multiple imputation, a reliable method for estimating missing values to produce more complete data. They then calculated age-adjusted incidence rates (equal to those of a normally distributed population) and survival rates at 5 and 10 years.
They found that, from 1976 to 2000, the age-adjusted rate of cervical cancer decreased significantly in Japan. However, in the 21st century, it reversed its course and began to climb. The rate of cervical cancer screening in Japan is very low at 40%. Although HPV vaccination was introduced in 2009, after only four years, the government stopped recommending it in the midst of announcements of suspected adverse events. Nevertheless, survival rates for cervical cancer have mostly increased, thanks to more effective treatment.
The current results are somewhat confusing, noted the researchers, as rising survival rates offset the increase in incidence. These survival rates are likely due to the success of concurrent chemotherapy and radiation therapy instead of radiation alone, as well as the official recommendation of its use.
In addition, the researchers pointed out that age could be negatively correlated with resistance to radiotherapy. As expected, overall survival rates were better in young people, but for localized cervical cancers, which are commonly treated by surgery or radiotherapy, elderly people (60 years and older) had a survival rate higher than that of younger people (40 to 59 years) undergoing radiotherapy.
"The increase in survival rates is certainly a good sign, but the increasing age-adjusted incidence is worrisome," said lead author Asami Yagi of Osaka University. "The finding that radiation may be less effective in younger patients with localized cervical cancer is surprising, but could prove useful. Our results should serve as a strong indicator of the need to take better preventive measures. These results can also provide insights into treatment choices. "
The article can be found at: Yagi et al. (2019) Epidemiological and clinical badyzes of cervical cancer using data from the Osaka population cancer registry.
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Source: Osaka University; Photo: Pixabay.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
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