OVARIAN CANCER & NULLIPARITY
- 1. Ø The strongest two sources we used are the pooled analysis and the prospective cohort studies. The weakest source is case control. Ø All the articles demonstrated a positive correlation between nulliparity and risk of ovarian cancer. Ø Some of the limitations of most of the studies are that they did not control for potential confounding variables such as socioeconomic status and age. Ø A few articles had potential risks for selection biases such as Berkson's bias and recall bias. Some women were admitted to the hospital for other medical conditions, which can increase the risk for ovarian cancer. Ø A possible reason for the positive association between nulliparity and ovarian cancer has been attributed to the changes that a woman undergoes during pregnancy. During this time, her ovaries do not release additional eggs, and there are changes in the levels of different hormones in her body. These changes are thought to help protect women against ovarian cancer. Ø Additionally, according to the pooled analysis article, another reason for this positive association is the “incessant ovulation” hypothesis, which postulates that every ovulation provokes micro- traumas to the ovaries and exposure to follicular fluid. This is suggested to increase the risk of ovarian cancer. Nulliparity and Ovarian Cancer Nour Matar -‐ Zaynab Albahrani – Jady Lubin – Sophia El moumni Epidemiology, Faculty of Health Sciences of the University of OUawa Discussion Results Introduction Methods Abstract References Pooled analysis Reproductive factors and risk of ovarian cancer Factors and Risk of Epithelial Ovarian Cancer Risk factors for ovarian cancer Hormonal risk factors for ovarian cancer Infertility, fertility drugs, and invasive ovarian cancer Risk Factors for Invasive Epithelial Ovarian Cancer Reproductive and hormonal factors and ovarian cancer Figure 1: Hierarchy of research design of the articles used from strongest to weakest Figure 2. Reprinted by: Riman, T., Dickman, P., Nilsson, S., Correia, N., & al, e. (2001). Risk Factors for Invasive Epithelial Ovarian Cancer: Results from a Swedish Case-Control Study, 367. Figure 3. Reprinted by: Mosgaard, B., Lidegaard, O., Kjaer, S.K., & al, e. (1997). Infertility, fertility drugs, and invasive ovarian cancer: a case-control study, 1008. Ø Ovarian cancer is an abnormal growth of cells in one or both of the ovaries that can spread to different parts of the body. Epithelial ovarian cancer is the most common, in which the spread of the cancer begins from the epithelial tissue covering the ovaries. Ø The main symptoms of epithelial ovarian cancer are abdominal pain, eating disorders and urinary problems (Webmed, 2013). Ø According to the American Cancer Society, approximately 21 290 women are newly diagnosed with ovarian cancer in America and about 14 180 women die because of it each year (American Cancer society, 2015). “Is there an association between nulliparity and the risk of developing ovarian cancer for women in North America and Europe?” Ø This study aimed to assess a relationship between ovarian cancer and and nulliparity ( i.e. does nulliparity increase the risk of developing ovarian cancer), through a structured literature review. Search Strategy “Nulliparity AND risk of ovarian cancer” Included Search Words: “United States of America”, “Canada”, “Europe”. Excluded any non-English articles Database used: Medline Ovid (n=233) After Reading Abstracts, Excluded: (n=1) Obesity (n=2) Specific Ethnicity (n=2) Infertility (n=4) Different cancers Studies Used (n=8) Prospective Cohort Studies (n=2) Case-Control Studies (n=5) Pooled Analysis (n=1) Potential Articles for Structured Literature Review (n=17) Conclusion Ø There was a positive correlation between nulliparity and ovarian cancer. Ø For future directions, more research should be done to reduce the amount of regular ovulations for women who decide not to have children in order to decrease the micro- traumas to the ovaries. However, it is important that this treatment does not result in any negative impacts on a woman’s health. Ø Furthermore, as stated in one of the aforementioned articles, further studies are needed to examine whether the various histological types of tumors have different etiologies (Hankinson, 1995). Association between nulliparity and the risk of ovarian cancer : A Structured Literature Review Nour Matar1, Zaynab Albahrani2, Jady Lubin3, Sophia El moumni4 1Fourth year Health Sciences student at the University of Ottawa. 2 Fourth year Health Sciences student at the University of Ottawa. 3 Fourth year Health Sciences student at the University of Ottawa. 4 Fourth year Health Sciences student at the University of Ottawa. Background: Ovarian cancer is the fifth most common type of cancer, especially in white women. About 50% of the diagnosis are among age 63 years and older (American Cancer Society, 2015). Previous studies have shown an association between reproductive factors such as nulliparity and postmenopausal ovarian cancer (Hankinson, 2012). Objective: To determine if an association exists between nulliparity and the development of ovarian cancer for women in North America and Europe. Method: Conducting a structured literature review through databases such as Medline (Ovid). Results: Obtained 17 different studies, chose 8 of which 2 were prospective cohort, 5 were Case-Control, 1 was a pooled analysis (meta-analysis). Obtained RRs , ORs, and CIs depending on the study. Conclusion: A positive correlation between nulliparity and the development of ovarian cancer was found. Figure 4. Reprinted by: Chiaffarino, F., Pelucchi, C., Parazzini, F., & al, e. (2001). Reproductive and hormonal factors and ovarian cancer, 339 Meta-‐Analysis Prospec/ve Cohort Case-‐Controls Name of Study Type of study Sample population Quantitative Measurements Results 1. Hormonal risk factors for ovarian cancer in the Albanian case-control study Case- control study Cases N = 283 Age: 24-74 Controls N = 1019 -Frequency and distribution analysis -Chi square test of Pearson -P-values (significant if <0.05) -Odds Ratios OR (12.5) -95% CI - Strong association between nulliparous women and ovarian cancer risk. - Decreased risk with increasing number of childbirths. 2. Pooled analysis of 3 European case-control studies: I. Reproductive factors and risk of epithelial ovarian cancer. Meta- analysis of 3 cases- controls studies (Italy, UK and Greece) 1st Study (Italy) Cases N = 755 Age: <75 Women with ovarian cancer Controls N = 2033 2nd Study (UK) Cases N = 235 Age: <65 Women with ovarian cancer Controls N = 451 3rd Study (Greece) Cases N = 150 Women with malignant ovarian cancer Controls N = 250 -Relative Risk 0 children RR (1) 1 child RR (0.7) 3 children RR (0.5) 4 children RR (0.3) -95 % CI - Nulliparity and delay of first birth until the age of 35 increases the risk. - Having more children is a protective factor for ovarian cancer. 3. Ovarian epithelial tumors and reproductive factors Case- control study Cases N = 1031 Age: median of 56 Women with histologically confirmed ovarian cancer Controls N = 2411 Age: median of 57 Women with the same geographical areas and admitted to the same hospitals as cases, with acute conditions unrelated to risk factors for ovarian cancer. -Odds ratio 3 births OR (0.6) > 4 births: OR (0.4) -95% CI Multiparity was associated with a significant reduction in risk of ovarian cancer. 4. Infertility, fertility drugs, and invasive ovarian cancer: a case- control study Case- control study Cases N = 684 Age: 18-59 Exclusion criteria: Non-Danish inhabitants, those who had malignancies other than ovarian cancer. Controls N = 1721 Women matched for area of residence and day/month of birth. Exclusion criteria: women who had undergone bilateral oophorectomy -Odds ratios 1 birth OR (0.47 to 1.02) ≥ 2 birth OR (0.33 to 0.69) -95% CI -Nulliparous women had an increased risk of ovarian cancer compared with parous women -Nulliparity implies a 1.5 to 2 fold increased risk of ovarian cancer. 5. Risk factors for invasive Epithelial Ovarian Cancer: Results from a Swedish Case- Control Study Case- control study Cases N = 655 cases Age: 50-74 Exclusion criteria: Women without any previous ovarian malignancies or bilateral oophorectomy. Controls N = 4148 Randomly selected women from a continuously updated population register Exclusion criteria: women who reported previous bilateral oophorectomy. -Parity reduced epithelial ovarian cancer risk -Odds ratio OR (0.61) for uniparous compared with nulliparous women. -95% CI -Parity reduced risk for uniparous compared with nulliparous women 6. Reproductive factors and risk of ovarian cancer: a prospective study Prospective cohort study N = 63,090 Age: 27-69 Exclusion criteria: surgical removal of one or both ovaries, or other operations on the ovaries or hysterectomy. -Odds ratios >5 births OR (0.4) -95% CI -The risk of ovarian cancer declined with increasing parity. 7. A Prospective Study of Reproductive Factors and Risk of Epithelial Ovarian Cancer Prospective cohort study N = 121,700 Age: 30-55 Female registered nurses Exclusion criteria: participants who were diagnosed with cancer or who removed one or both ovaries. -Relative Risk (RR) between parity and ovarian cancer = 0.84 -95% CI -A statistically significant inverse association was observed between parity and ovarian cancer risk. 8. Risk Factors for Ovarian Cancer: a case control-study Case Control Study Cases N = 235 Diagnosed with epithelial ovarian cancer Controls N = 451 -Relative risk (RR) between parity and ovarian cancer = 1.7 -95 % CI -Nulliparous women had a higher risk of ovarian cancer than parous women American Cancer society. (March 12th 2015) What are the key sta/s/cs about ovarian cancer? hUp://www.cancer.org/cancer/ovariancancer/detailedguide/ovarian-‐cancer-‐key-‐sta/s/cs. March 23th 2015 Booth, M., Beral, V., & Smith, P. (1989). Risk factors for ovarian cancer: A case-‐control study. Bri%sh Journal of Cancer, 60(4), 592-‐598. Chiaffarino, F., Pelucchi, C., Parazzini, F., Negri, E., Franceschi, S., Talamini, R., La Vecchia, C. (2001). Reproduc/ve and hormonal factors and ovarian cancer. Annals of Oncology; Ann.Oncol., 12(3), 337-‐341. Hankinson, S. E., Colditz, G. A., Hunter, D. J., WilleU, W. C., Stampfer, M. J., Rosner, B., . . Speizer, F. E. (1995). A prospec/ve study of reproduc/ve factors and risk of epithelial ovarian cancer. Cancer, 76(2), 284-‐290. doi:10.1002/1097-‐0142(19950715)76:2<284::AID-‐CNCR2820760219>3.0.CO;2-‐5 Kvale, G., Heuch, I., Nilssen, S., & Beral, V. (1988). Reproduc/ve factors and risk of ovarian cancer: A prospec/ve study. Interna%onal Journal of Cancer, 42(2), 246-‐251. Mosgaard, B. J., Schou, G., Lidegaard, Ø., Andersen, A. N., & Kjaer, S. K. (1997). Infer/lity, fer/lity drugs, and invasive ovarian cancer: A case-‐ control study. Fer%lity and Sterility, 67(6), 1005-‐1012. doi:10.1016/S0015-‐0282(97)81431-‐8 Negri, E., Franceschi, S., Tzonou, A., Booth, M., Lavecchia, C., Parazzini, F., . Trichopoulos, D. (1991). Pooled analysis of 3 european case-‐ control studies .1. reproduc/ve factors and risk of epithelial ovarian-‐ cancer. Interna%onal Journal of Cancer; Int.J.Cancer, 49(1), 50-‐56. Pajenga, E., Rexha, T., Celiku, S., Bejtja, G., & Pisha, M. (2013). Hormonal risk factors for ovarian cancer in the albanian case-‐ control study. Bosnian Journal of Basic Medical Sciences; Bosnian J.Basic Med.Sci., 13(2), 89-‐93. Riman, T., Nilsson, S., Dickman, P. W., Correia, N., Magnusson, C. M., Persson, I. R., & Nordlinder, H. (2002). Risk factors for invasive epithelial ovarian cancer: Results from a swedish case-‐ control study. American Journal of Epidemiology, 156(4), 363-‐373. doi:10.1093/aje/kwf048 Webmed. (June 28 2013) What is ovarian cancer :topic overview hUp://www.webmd.com/ovarian-‐cancer/guide/ovarian-‐cancer-‐topic-‐overview. April 1st 2015.