Ovaries are the organs of the female reproductive system that produce eggs. Women and people with ovaries may be at risk of ovarian cancer. Risk factors for ovarian cancer include obesity, not having given birth (nulliparity), late menopause, use of hormone replacement therapy and a family history of the disease.1 Ovarian cancer is often detected at a late stage when it has spread to other regions in the body, making treatment difficult and reducing the chances of survival. Treatment for ovarian cancer may lead to infertility and early menopause, as well as side effects from surgery and chemotherapy.2
In Australia in 2024, 1,805 people were diagnosed with ovarian cancer (including serous carcinomas of the fallopian tube)3 and 1,054 people died from this form of cancer.4 Based on data from the period 2015–2019, it is estimated that approximately 49% of people survive for 5 years or more after diagnosis with ovarian cancer.5
There are three main types of ovarian cancer that differ depending on the type of ovarian cells from which the cancer is derived. Over 90% of ovarian cancers are the epithelial type, meaning that they occur in the external surfaces of the ovaries. Epithelial ovarian cancers are further subdivided into 5 common subtypes of cancer. Of these, only mucinous ovarian cancer is associated with smoking.1 Mucinous ovarian cancer is a rare subtype that occurs in approximately 3% of people diagnosed with ovarian cancer.1 However, mucinous is the most frequently diagnosed subtype of ovarian cancer in women under 40 years.6 Some of the common risk factors for other types of ovarian cancer (nulliparity, late menopause and BRCA gene mutations) do not seem to be risk factors for the mucinous subtype.6
Living with ovarian cancer can be difficult. Many people diagnosed with ovarian cancer have a late-stage disease that may be fatal for them. Treatments for ovarian cancer have difficult side effects and may lead to early menopause and the inability to get pregnant.2
3.5.11.1 Risk associated with smoking
The International Agency for Research on Cancer (IARC) has concluded that smoking is a cause of mucinous ovarian cancer.7 This is a rare subtype of cancer that makes up approximately 3% of ovarian cancer diagnoses.1 A meta-analysis of 51 studies found that smoking was associated with a 1.8-fold increased risk of mucinous ovarian cancer, but not other subtypes, compared to people who have never smoked.8
3.5.11.2 How tobacco smoke causes ovarian cancer
To date, the mechanisms by which smoking causes mucinous ovarian cancers are unknown.
3.5.11.3 Factors affecting risk
Intensity and duration of smoking
A meta-analysis published in 2006 found that the risk of mucinous ovarian cancer increased with increasing intensity of smoking; from 1.5-fold for the lowest pack-years to 2.5-fold for highest pack-years of smoking, compared to never smokers.9
A study of over 300,000 women found that those who smoked for a longer duration had a higher risk of mucinous ovarian cancer. Women who smoked for 10–19 years had a 1.7-fold increased risk of mucinous ovarian cancer compared to never smokers, but those who smoked for 20+ years had a 2.3-fold higher risk.10 Two other large studies have found similar effects of smoking intensity and duration on the risk of mucinous ovarian cancer.11,12
Subtypes of mucinous cancer
Mucinous ovarian cancer can be divided into two subtypes: invasive (fully cancerous) and borderline malignant (lower risk tumours that may not progress to invasive cancer). Compared to never smokers, women who were current smokers at the time of diagnosis had a 2.3-fold increased risk of borderline malignant and a 1.3-fold increased risk of invasive mucinous ovarian cancer.8
Smoking cessation
A meta-analysis published in 2006 found that the excess risk of mucinous ovarian cancers for people who smoke returned to that of never smokers within 20–30 years of smoking cessation.9
3.5.11.4 Impact of smoking on prognosis
Although smoking is only associated with the incidence of one of the five subtypes of epithelial ovarian cancers, there is evidence that current smoking at the time of diagnosis can increase the risk of mortality of people with epithelial ovarian cancer in general. In one study, women with epithelial ovarian cancer who smoked at the time of diagnosis were 1.4 times more likely to die early compared to non-smokers. In this study, only 6% of the women had mucinous ovarian cancer, whereas the other 94% had one of the other subtypes.13 A pooled analysis of 19 studies found that women who smoked at diagnosis had a higher risk of mortality if they had mucinous or serous (the most common subtype) ovarian cancers.14
In a study of women receiving treatment for mucinous ovarian cancer, those who smoked at the time of diagnosis had a higher risk of their cancer spreading and of dying early compared to never smokers.15
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References
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2. Cancer Council Australia. Understanding ovarian cancer., 2024. Available from: https://www.cancer.org.au/assets/pdf/understanding-ovarian-cancer-booklet.
3. Australian Institute of Health and Welfare. Cancer data in Australia. Data tables: CDIA 2024: Book 1a – Cancer incidence (age-standardised rates and 5-year age groups) Canberra: AIHW. 2024. Available from: https://www.aihw.gov.au/reports/cancer/cancer-data-in-australia/data.
4. Australian Institute of Health and Welfare. Cancer data in Australia. Data tables: CDIA 2024: Book 2a – Cancer mortality (age-standardised rates and 5-year age groups) Canberra: AIHW. 2024. Available from: https://www.aihw.gov.au/reports/cancer/cancer-data-in-australia/data.
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8. Collaborative Group on Epidemiological Studies of Ovarian C, Beral V, Gaitskell K, Hermon C, Moser K, et al. Ovarian cancer and smoking: individual participant meta-analysis including 28,114 women with ovarian cancer from 51 epidemiological studies. Lancet Oncology, 2012; 13(9):946-56. Available from: https://www.ncbi.nlm.nih.gov/pubmed/22863523
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14. Praestegaard C, Jensen A, Jensen SM, Nielsen TS, Webb PM, et al. Cigarette smoking is associated with adverse survival among women with ovarian cancer: Results from a pooled analysis of 19 studies. International Journal of Cancer, 2017; 140(11):2422-35. Available from: https://www.ncbi.nlm.nih.gov/pubmed/28063166
15. Kelemen LE, Warren GW, Koziak JM, Kobel M, and Steed H. Smoking may modify the association between neoadjuvant chemotherapy and survival from ovarian cancer. Gynecologic Oncology, 2016; 140(1):124-30. Available from: https://www.ncbi.nlm.nih.gov/pubmed/26549109