Cancer patients are 20 times more likely to commit suicide within the first year of their diagnosis than members of the general population, according to new findings.

The study, released Tuesday by a research team at the National Cancer Center, cites psychological stress and change of lifestyle due to the disease and its treatment, as well as a decline in patients' physical and mental abilities, as potential factors behind the high suicide rate.

"We should think of suicides and other accident-related deaths (of cancer patients) as something which can be prevented," Takashi Yamauchi, a researcher at the National Center of Neurology and Psychiatry and a member of the research team, told reporters. "It is necessary to strengthen support measures for patients especially during the period with high risks."

The group studied some 103,000 residents in nine prefectures over about a 20-year span until 2010. The subjects were aged between 40 and 69 at the start of the research.

Among them, 561 committed suicide, 13 of whom had been diagnosed with cancer less than a year before, according to the report. The rate was 23.9 times higher than among the noncancer population, it said.

The suicide risk, however, was largely the same beyond a year after the cancer diagnosis.

The report also said that the risk of death by "external causes," such as accidents, was 18.8 times higher for those diagnosed with cancer within one year. Of the 755 who died of external causes, 16 had been diagnosed with cancer within a year of their death, the report said.

Again, the difference in rate largely disappeared a year after the cancer diagnosis.