According to one study, prolonged smoking cessation is associated with a reduction in the risk of cancer 10 years after quitting smoking. Eunjung Park, Ph.D., of the National Cancer Center Graduate School of Cancer Science and Policy in Goyang, South Korea, and colleagues examined the time course of cancer risk by time since smoking cessation in a study retrospective cohort study involving 2,974,820 people. Korean participants aged 30 years and older.
The result of research was published online in JAMA Network Open.
Cancer: why it is essential to stop smoking
Researchers confirmed 196,829 cancer cases during an average follow-up of 13.4 years. Those who quit completely had a lower risk of cancer than continued smokers, with a hazard ratio of 0.83 for all cancer sites and 0.58, 0.73, 0.86, and 0.80 for lung, respectively. , liver, stomach and colorectal.
Cancer risk was slightly elevated in the 10 years after smoking cessation compared with continued smoking and then decreased over time; after 15 or more years, the risk reached 50% of that associated with continued smoking.
The risk of lung cancer decreased three years earlier than that of other cancers, and a greater relative reduction was observed. A greater reduction in lung cancer risk was observed in association with dropping out before age 50 compared with age 50 years or older (hazard ratios, 0.43 and 0.61, respectively).
“Our findings highlight the importance of promoting smoking cessation, offering adequate support and resources for sustained cessation, and encouraging cessation at an early age to reduce cancer risk,” the authors write.
Former smokers avoid more than half of the excess cardiovascular, cancer, and respiratory mortality associated with current smoking within the first decade after quitting.
Blake Thomson, D.Phil., and Farhad Islami, M.D., Ph.D., of the American Cancer Society in Atlanta, examined the association between the years since quitting smoking and mortality. Current smokers and never smokers were compared to former smokers who had quit 1 to 9, 10 to 19, 20 to 29, and 30 or more years before recruitment for cardiovascular, cancer, and respiratory deaths. aged between 25 and 89.
The researchers identified 11,860 cardiovascular deaths, 10,935 cancers, and 2,060 respiratory deaths during 5.0 million person-years of follow-up in the 438,015 adults included. Ratios between current and never-smokers were 2.30, 3.38, and 13.31 for cardiovascular, cancer, and respiratory mortality, respectively. Ex-smokers avoided 64%, 53%, and 57% of the excess cardiovascular, cancer, and respiratory mortality associated with current smoking within the first decade after quitting, respectively, with additional benefits accruing over time.
Little or no excess cardiovascular mortality was observed 20 to 29 years after quitting smoking among former smokers. Former smokers avoided approximately 100%, 93%, and 97% of the excess cardiovascular, cancer, and respiratory mortality associated with continued smoking after 30 or more years of smoking cessation, respectively.
“These findings highlight that with prolonged cessation, cause-specific mortality rates among former smokers may eventually approach those of never-smokers,” the authors write.
Starting smoking at any age is associated with an increased cancer death rate, while quitting, especially at a younger age, can avoid most of this risk.
Blake Thomson, D.Phil., of the American Cancer Society of Atlanta, and colleagues conducted a prospective cohort study to examine the correlation between age at smoking initiation and cessation and cancer mortality among those aged 25 and 79 years old.
The researchers found 10,014 cancer deaths between the ages of 25 and 79 among 410,231 participants with 3.7 million person-years of follow-up. The overall cancer death rate ratio associated with smokers was 3.00 compared to nonsmokers.
The rate ratios were 4.01, 3.57, 3.15, 2.86, and 2.44 for those starting at ages younger than 10, 10 to 14, 15 to 17, 18 to 20, and from 21 years old and over. If these excesses were interpreted primarily as causal, smoking would account for 75 and 59 percent of cancer deaths among those who begin smoking before age 10 and at age 21 or older, respectively.
Compared to nonsmokers, the rate ratios were 0.95, 1.23, 1.45, and 1.88 for those who quit smoking at ages 15-34, 35-44, 45-54, and 55-64. years, respectively, resulting in the avoidance of approximately 100, 89, 78, and 56% of the excess risk of cancer mortality observed in association with continued smoking.
“Widespread smoking cessation among individuals who currently smoke could substantially reduce cancer mortality in the coming years,” Thomson said in a statement.
Smoking has a negative impact on long-term survival after breast cancer. Quitting smoking after diagnosis can reduce your risk of dying from breast cancer.
This study aimed to examine whether smoking at diagnosis and changes in smoking within five years of diagnosis were associated with long-term breast cancer mortality.
In a population-based study of 1,508 women on Long Island with
breast cancer, subjects were interviewed and asked a series of questions, including about smoking habits. At the five-year follow-up, participants answered the same questions, which asked about the length of time since the original questionnaire.
Although breast cancer survival rates in the United States are high, estimated at 90 percent five years after diagnosis, approximately 40,000 women will die from breast cancer in 2017. This makes breast cancer the second leading cause of breast cancer-related death. cancer among women.
Compared to nonsmokers, the risk of all-cause mortality was elevated in 19% of smokers at diagnosis. The risk of all-cause mortality was further increased among the 8% of women who were smokers before or after diagnosis, but was reduced among the 11% of women who stopped smoking after diagnosis.
Compared to non-smokers, smoking at the time of breast cancer diagnosis was associated with a 69% increased risk of all-cause mortality. The risk of all-cause mortality was increased by 50% for current smokers who smoked fewer than 20 cigarettes per day and by 85% for current smokers who smoked more than 20 cigarettes per day. All-cause mortality also increased among former smokers and among current smokers who had smoked for more than 30 years.
The risk of all-cause mortality was 130% elevated among women who continued to smoke after diagnosis compared with those who had never smoked. Although the risk of all-cause mortality remained elevated among women who stopped smoking after diagnosis, the increased mortality risk was estimated at 83% compared to nonsmokers. Similar patterns were observed for the risk of breast cancer-specific mortality, which was elevated by 60% among women who continued to smoke after diagnosis, but was not elevated among those who stopped smoking, compared with those who stopped smoking. they had never smoked.
Study results show that smoking has a negative impact on long-term survival after breast cancer. For the 10-20% of women who were smokers at the time of their breast cancer diagnosis, quitting smoking is an important behavioral change that can improve survival after breast cancer.
“Studies on smoking and breast cancer survival have generally focused on smoking at the time of diagnosis as a prognostic indicator,” said study author Dr. Humberto Parada of the University of North Carolina at Chapel Hill. changes in smoking and show that quitting smoking after diagnosis may be important for improving survival among women with breast cancer. Future studies should continue to investigate the mechanisms by which smoking affects breast cancer-specific survival.
Potential survival cohorts like this “help quantify the mortality burden faced by active smokers with malignancies not traditionally thought to be related to smoking,” Michael N. Passarelli and Polly A. Newcomb wrote in an accompanying editorial I study. “Evidence that smoking cessation benefits even those who quit soon after diagnosis should serve as ongoing motivation for breast cancer survivors to pursue positive health behavior changes.”
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