RESEARCH ARTICLE


Relationships Between Percentage of Forest Coverage and Standardized Mortality Ratios (SMR) of Cancers in all Prefectures in Japan



Qing Li*, Maiko Kobayashi , Tomoyuki Kawada
Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.


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Creative Commons License
Li et al.; Licensee Bentham Open

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Hygiene and Public Health, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan; E-mails: qing-li@nms.ac.jp


Abstract

Objectives:

To explore whether forest coverage affects the rate of deaths due to cancers in Japan, we investigated the relationships between the percentage of forest coverage and standardized mortality ratios due to cancers in all prefectures in Japan.

Methods:

Data on the percentage of forest coverage in all prefectures in Japan were collected from the database of the Forestry Agency of Japan. Data on standardized mortality ratios (SMR) due to lung, stomach, kidney, and colon cancers in males and females, breast and uterine cancers in females, and prostate cancer in males, and data of smoking status of males and females in all prefectures in Japan were collected from the database of the Ministry of Health, Labour, and Welfare of Japan. Human development index (HDI) was used as a parameter of the socioeconomic status of each prefecture. The correlation and partial correlation coefficients between the percentage of forest coverage and SMR of cancers, after controlling for the effects of smoking and the socioeconomic status, were calculated.

Results:

People living in areas with lower forest coverage had significantly higher SMR of cancers compared with the people living in areas with higher forest coverage. There were significant inverse correlations between the percentage of forest coverage and the SMR of lung, breast, and uterine cancers in females, and the SMR of prostate, kidney, and colon cancers in males in all prefectures in Japan, even after the effects of smoking and socioeconomic status were factored in.

Conclusions:

These findings indicate that increased forest coverage may partially contribute to a decrease in mortality due to cancers in Japan.

Keywords: Breast cancer, colon cancer, HDI, kidney cancer, percentage of forest coverage, prostate cancer, SMR, uterine cancer.