'Distressing' Trend: Cervical Cancer Increasing in Japan

Megan Brooks

January 07, 2019

Cervical cancer is on the rise among young women in Japan. This contrasts with the trend seen in most other developed countries, where rates have been falling, largely as a result of screening and vaccination against human papillomavirus (HPV) — the chief cause of virtually all cervical cancers worldwide.

The recent increase in cervical cancer in Japan can probably be explained by several factors, say researchers: low levels of cervical cancer screening, changes in sexual behavior leading to an increase in the prevalence of HPV infection, and the suspension in June 2013 of an active recommendation of HPV vaccination.

"The most important finding in the paper is increasing incidence of cervical cancer among recent birth cohort in Japan, suggesting an increasing prevalence of HPV," Mai Utada, PhD, of the Department of Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan, told Medscape Medical News.

"Screening and vaccination have been shown to be highly effective and, if duly strengthened, would help reverse the distressing cervical cancer trends in Japan," Utada and colleagues write.

The study was published online November 25 in the International Journal of Cancer.

An "Urgent Concern"

Using registry data, the researchers analyzed trends in the incidence of cervical cancer in Japan from 1985 to 2012, relative to trends among Japanese Americans in Surveillance, Epidemiology, and End Results (SEER) registries and among women in South Korea in the Korea Central Registry.

According to the Japanese registry data, 6760 invasive cervical cancer cases were diagnosed in women aged 20 to 84 between 1985 and 2012. Incidence rates in Japan have been rising since the late 1990s, driven largely by a cohort effect of increasing risk in birth cohorts after 1960, the researchers say.

Between 1997 and 2012, the age-standardized incidence rate increased significantly by 2.6% per year, after a significant decline of 1.7% per year between 1985 and 1997, they report.

Trends in age-specific incidence rates varied. Among women younger than 50 years, there was a steady, significant increase in incidence rates between 1985 and 2012. The highest annual percentage change per year occurred in the youngest women (5.1% for women aged 20 to 29, 3.2% for those aged 30 to 39, and 1.7% for women aged 40 to 49).

Incidence rates were stable among women aged 50 to 54. For those aged 55 years and older, incidence rates decreased significantly in the 1980s and 1990s.

Notably, say the researches, the increasing cervical cancer risk seen among recent birth cohorts in women in Japan was not observed in Japanese American or South Korean women. In contrast, the incidence rate was declining among Japanese American women of all ages and in all but the youngest (<30 years) South Korean women.

The increasing risk for cervical cancer among young women in Japan is "an urgent concern," Utada and colleagues say. It is likely related to "increasing HPV infection prevalence unopposed by comprehensive screening and, going forward, HPV vaccination," they write.

Cervical cancer screening was initiated in Japan in 1983, but there is no systematic call-and-recall system, and there is wide variation in screening. Nationally, screening uptake remains low, the researchers note. Screening uptake in the United States and South Korea is significantly higher than in Japan.

As for vaccination, the Japanese Ministry of Health, Labour, and Welfare's 2013 recommendation to suspend HPV vaccine led to a drastic decline in vaccination rate, the authors note. As previously reported by Medscape Medical News, the rate of newly vaccinated girls in fiscal year 2013 dropped from the usual rate of approximately 70% per year to 1.1% in 12-year-old girls and to 3.9% in 13-year-old girls.

HPV prevalence is tied to the age at which sexual activity starts. In Japan, because of shifts in attitudes toward sexuality among teenagers, girls are having sex at younger ages, the researchers note. It is likely that similar changes occurred in the United States and South Korea, but in those countries, rates of screening may have increased, they say.

In March 2017, the American Society of Clinical Oncology issued a global guideline offering evidence-based recommendations on the use of HPV vaccination for the prevention of cervical cancer. The guideline took into account the varying levels of economic and structural resources, depending on the circumstances of each country.

Last May, the World Health Organization called for all countries to take action to help end the suffering caused by cervical cancer.

The study was supported by grants from the Radiation Effects Research Foundation, Japanese Ministry of Health, Labour and Welfare, and the US Department of Energy. The authors have disclosed no relevant financial relationships.

Int J Cancer. Published online November 25, 2018. Abstract

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