While Japan has consistently boasted one of the best reports cards in the world on health, cancer, the leading cause of death here, has remained a black spot.
But a recent study analyzing the cause of domestic cancer diagnoses and deaths concludes it doesn’t have to, and shouldn’t be so.
About half of the cancer cases and deaths in Japan are preventable, according to the study, conducted by the Japanese National Cancer Center that is to be published in the international medical journal Annals of Oncology. The study’s conclusions are based on known preventable risk factors in Japan in 2005, drawing on various nationwide statistics related to exposure levels to cancer causes around 1990 as well as Japanese epidemiological studies that measure the relative risk of being diagnosed with and dying from cancer. The results were announced at the Japanese Cancer Association’s annual meeting earlier this month.
While genetics naturally places some people at a higher risk of contracting cancer, the research shows that the bulk of the cases are linked to lifestyle choices. And the biggest culprit is one of Japan’s favorite vices: smoking. The habit played a role in about 20% of avoidable cancer diagnoses, and 23% of deaths among men and women, according to the study.
It was by and large the leading agent among men, accounting for a third of cancer diagnoses and slightly more in ones that led to death. It had a looser hold on women among whom it caused about 5% of cases. Japan isn’t alone in this reality, of course: The World Health Organization estimates tobacco causes an estimated 22% of cancer deaths per year, making it the greatest avoidable risk factor for cancer mortality worldwide.
Although the smoking rate has been steadily decreasing here, the adverse long-term effects from when the country was a smoking haven have started to show. Lung cancer is the most prevalent kind of malignancy among both men and women, comprising nearly 20% of all cancer cases in 2009, the latest year for which numbers are available, according to the National Cancer Center. That is a shift from as recently as 2005, when stomach cancer ranked at the top. As of 2009, one in 16 men was at risk of dying from lung cancer and one in 47 for women. There were about 344,100 cancer deaths in 2009.
Viral infections are the second greatest cause of preventable cancer. They played a part in a little over 20% of preventable cancer diagnoses. It is a steep difference compared to the some 5% of cancer cases in which viruses have a role in Europe and the U.S., said the study’s notes.
The research group said the most common infectious illnesses are hepatitis C and the helicobacter pylori, a bacterium that lives in the stomach. While the illnesses make one more susceptible to cancer of the liver or stomach it can be avoided by controlling lifestyle habits that don’t aggravate the virus, like heavy alcohol intake in the case of hepatitis C. The viruses were the top contributor to preventable cancer cases and deaths among women, at 17.5% and 19.4% respectively. But because most of those infected with the viruses are older — in the case of h.pylori, a remnant of the harsh living conditions in Japan in the immediate post-World War II era — the research group expects the number of domestic viral-related cancer cases to naturally decrease.
Another vice, alcohol, was the third biggest cause – behind about 6% of cancer cases for men and women.
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