A framework for assessing interactions for risk stratification models: the example of ovarian cancer

Generally, risk stratification models for cancer use effect estimates from risk/protective factor analyses that have not assessed potential interactions between these exposures. We have developed a 4-criterion framework for assessing interactions that includes statistical, qualitative, biological, and practical approaches. We present the application of this framework in an ovarian cancer setting because this is an important step in developing more accurate risk stratification models. Using data from 9 case-control studies in the Ovarian Cancer Association Consortium, we conducted a comprehensive analysis of interactions among 15 unequivocal risk and protective factors for ovarian cancer (including 14 non-genetic factors and a 36-variant polygenic score) with age and menopausal status. Pairwise interactions between the risk/protective factors were also assessed. We found that menopausal status modifies the association among endometriosis, first-degree family history of ovarian cancer, breastfeeding, and depot-medroxyprogesterone acetate use and disease risk, highlighting the importance of understanding multiplicative interactions when developing risk prediction models.

A comparative study on behavior, awareness and belief about cervical cancer among rural and urban women in Vietnam

Cervical cancer is the second most common gynecologic cancer in Vietnam but based on the literature, only ~25% of Vietnamese women reported ever being screened for cervical cancer. To inform strategies to reduce the cervical cancer burden in Southern Vietnam where disease incidence is higher than the national average, this study examined behaviors, awareness, barriers, and beliefs about cervical cancer screening among rural and urban women in this geographical region. In October-November 2021, we conducted a cross-sectional study among 196 rural and 202 urban women in Southern Vietnam; participants completed a cervical cancer screening questionnaire. Descriptive analyses and rural-urban differences in screening behavior, awareness, barriers, and beliefs are presented. About half of the rural and urban participants reported ever being screened for cervical cancer. Most participants showed high perceived severity of cervical cancer and benefits of screening. Further, they reported that they would screen if it was recommended by doctors and/or friends/family. However, most women showed low awareness and perceived susceptibility to cervical cancer. Logistical and psychosocial barriers to physician-based screening methods were reported. Based on our results, the World Health Organization 2030 goals for cervical cancer screening are not currently met in Southern Vietnam. Increasing health literacy and engaging doctors and family members/social networks emerged as important avenues to improve screening. HPV (Human papillomavirus) self-sampling is also a potential approach to increase uptake of cervical cancer screening given the identified psychosocial and logistical barriers.

Trends of Ovarian Cancer Incidence by Histotype and Race/Ethnicity in the United States 1992-2019

The effect of risk factors on ovarian cancer differs by histotype, and the prevalence of such risk factors varies by race/ethnicity. It is not clear how ovarian cancer incidence has changed over time by histotype and race/ethnicity. We used the Surveillance, Epidemiology, and End Results Program (SEER-12) 1992-2019 data to examine the trend of ovarian cancer incidence for three histotypes (high-grade serous N = 19,691, endometrioid N = 3,212, and clear cell N = 3,275) and four racial/ethnic groups (Asian/Pacific Islander, Hispanic, non-Hispanic Black, and non-Hispanic White). Joinpoint and age-period-cohort analyses were conducted to analyze ovarian cancer incidence trends. High-grade serous cancer was the most common histotype, but its incidence has significantly decreased over time for all racial/ethnic groups; the decrease was largest for non-Hispanic White women (average annual percent change AAPC during 2010-2019 = -6.1; 95% confidence interval (CI), -8.0 to -4.2). Conversely, clear cell cancer was most common in the Asian/Pacific Islanders, and its incidence has increased over time, particularly among Hispanic and Asian/Pacific Islander women (AAPC during 2010-2019 = 2.8; 95% CI, 0.8 to 4.7, and AAPC = 1.5; 95% CI, 0.7 to 2.2, respectively). Endometrioid cancer incidence has decreased in non-Hispanic White but increased in Hispanic women (AAPC during 2010-2019 = -1.3; 95% CI, -1.9 to -0.8, and AAPC = 3.6; 95% CI, 1.0 to 6.3, respectively). The differential incidence trends by histotype and race/ethnicity underscore the need to monitor incidence and risk factor trends across different groups and develop targeted preventive interventions to reduce the burden of ovarian cancer and disparity by race/ethnicity.

Significance

During 1992-2019, high-grade serous ovarian cancer incidence has decreased while clear cell cancer incidence has increased regardless of race/ethnicity. Endometrioid cancer incidence has decreased in non-Hispanic White but increased in Hispanic women. Differential ovarian cancer incidence trends highlight the need for targeted preventive interventions by histotype and race/ethnicity.

Lifestyle and personal factors associated with having macroscopic residual disease after ovarian cancer primary cytoreductive surgery

OBJECTIVE

The presence of macroscopic residual disease after primary cytoreductive surgery (PCS) is an important factor influencing survival for patients with high-grade serous ovarian cancer (HGSC). More research is needed to identify factors associated with having macroscopic residual disease. We analyzed 12 lifestyle and personal exposures known to be related to ovarian cancer risk or inflammation to identify those associated with having residual disease after surgery.

METHODS

This analysis used data on 2054 patients with advanced stage HGSC from the Ovarian Cancer Association Consortium. The exposures were body mass index, breastfeeding, oral contraceptive use, depot-medroxyprogesterone acetate use, endometriosis, first-degree family history of ovarian cancer, incomplete pregnancy, menopausal hormone therapy use, menopausal status, parity, smoking, and tubal ligation. Logistic regression models were fit to assess the association between these exposures and having residual disease following PCS.

RESULTS

Menopausal estrogen-only therapy (ET) use was associated with 33% lower odds of having macroscopic residual disease compared to never use (OR = 0.67, 95%CI 0.46-0.97, p = 0.033). Compared to nulliparous women, parous women who did not breastfeed had 36% lower odds of having residual disease (OR = 0.64, 95%CI 0.43-0.94, p = 0.022), while there was no association among parous women who breastfed (OR = 0.90, 95%CI 0.65-1.25, p = 0.53).

CONCLUSIONS

The association between ET and having no macroscopic residual disease is plausible given a strong underlying biologic hypothesis between this exposure and diagnosis with HGSC. If this or the parity finding is replicated, these factors could be included in risk stratification models to determine whether HGSC patients should receive PCS or neoadjuvant chemotherapy.

Effects of risk factors for ovarian cancer in women with and without endometriosis

OBJECTIVE

To evaluate the associations between 10 well-established ovarian cancer risk factors and risk of ovarian cancer among women with vs. without endometriosis.

DESIGN

Pooled analysis of 9 case-control studies in the Ovarian Cancer Association Consortium.

SETTING

Population-based.

PATIENT(S)

We included 8,500 women with ovarian cancer, 13,592 control women.

INTERVENTION(S)

Ten well-established ovarian cancer risk factors.

MAIN OUTCOME MEASURE(S)

Risk of ovarian cancer for women with and without endometriosis.

RESULT(S)

Most risk factor-ovarian cancer associations were similar when comparing women with and without endometriosis, and no interactions were statistically significant. However, body mass index (BMI) 25-<30 kg/m² was associated with increased ovarian cancer risk among women with endometriosis (odds ratio [OR] = 1.27, 95% confidence interval [CI] 1.00-1.60), but not associated with the risk among women without endometriosis (OR = 0.97; 95% CI, 0.91-1.05) when compared with BMI 18.5-<25 kg/m²; an increased risk was observed for a BMI ≥30 kg/m², although there was little difference comparing women with endometriosis (OR = 1.21; 95% CI, 0.94-1.57) to women without (OR = 1.13; 95% CI, 1.04-1.22) (P-interaction = .51). Genital talcum powder use and long-term menopausal estrogen-only therapy use showed increased ovarian cancer risk, but risk appeared greater for those with endometriosis vs. those without (genital talcum powder: OR = 1.38; 95% CI, 1.04-1.84 vs. OR = 1.12; 95% CI, 1.01-1.25, respectively; ≥10 years of estrogen-only therapy: OR = 1.88; 95% CI, 1.09-3.24 vs. OR = 1.42; 95% CI, 1.14-1.76, respectively); neither of these interactions were statistically significant (P-interaction = .65 and P-interaction = .96, respectively).

CONCLUSION(S)

The associations between ovarian cancer and most risk factors were similar among women with and without endometriosis. However, there was some suggestion of differences by endometriosis status for BMI, menopausal hormone therapy use, and genital talcum powder use, highlighting the complexity of ovarian cancer etiology.

Abstract 21: Awareness of HPV and experience with cervical cancer screening in rural Southern Vietnam

Background: Cervical cancer is the fifth most common female cancer in Vietnam; incidence rates are higher in Southern compared to Northern areas. Several studies have found that most Southern urban women lacked knowledge of Human papillomavirus (HPV) and had never been screened for cervical cancer, however, no studies have been conducted in Southern rural areas. We therefore conducted a cross-sectional study aimed at exploring awareness of HPV and attitudes toward and experience with cervical cancer screening among rural women in Southern Vietnam. We were particularly interested in whether HPV self-sampling was acceptable in this population.

Methods: In October and November 2021, 198 women aged 28-65 living in the rural Can Gio district of Ho Chi Minh City were recruited for the study. Participants were asked to complete an HPV awareness questionnaire in Vietnamese. They then watched four short Vietnamese dubbed and subbed videos demonstrating cervical cancer screening methods (Pap smear, visual inspection with acetic acid application [VIA], HPV sampling by a physician, and HPV self-sampling) before answering questions about their views and experience with each screening method. Chi-square tests were used to evaluate differences in HPV awareness and screening history by age, marital status, religion, education level and household income. Logistic regression models were fit to test for associations between and trends in HPV awareness and screening experience with age, education level and income.

Results: Of the 198 participants, 67 (34%) had ever heard of HPV. Women with higher education levels and higher income were more likely to have heard of HPV (p-trend&lt;0.001 and 0.027, respectively). There was no difference in having heard of HPV by marital status (p=0.99), religion (p=0.20), or age (p-trend=0.51). Less than half of the participants (n=85; 43%) had ever been screened for cervical cancer; the was no association between being screened and age, marital status, religion, education level or income. Among women who had been screened for cervical cancer (n=85), the most common method was Pap smears (n=69; 81%), followed by HPV testing with a sample collected by a physician (n=20; 24%), VIA (n=15; 18%), and HPV self-sampling (n=2; 2%). Some women had been screened with multiple methods. Among all women, 84% reported being willing to have a Pap smear (n=167) whereas only 40% indicated they would be interested in HPV self-sampling (n=79). The most common concerns regarding HPV self-sampling included: self-collecting incorrectly (n=158; 80%), pain (n=106; 54%), and fear of the test revealing that they had cancer (n=91; 46%).

Conclusions: Rural women in Southern Vietnam lacked knowledge of HPV, however 43% had been screened for cervical cancer. Education programs are needed to increase awareness of HPV, and address the concerns regarding HPV self-sampling given its potential to increase screening uptake in low-resource areas.

Citation Format: Minh Tung Phung, Hong H.T.C. Le, Tuong Vy Nguyen, Nhat Vy Tran, Lan Y Vo, Thao Nguyen Thi Thu, Phan P.H.T. Dung, Rafael Meza, Tran Ngoc Dang, Pham Le An, Celeste Leigh Pearce. Awareness of HPV and experience with cervical cancer screening in rural Southern Vietnam [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 21.

Abstract 2248: Environmental factors associated with residual disease after ovarian cancer primary cytoreduction surgery

Background: Ovarian cancer is the deadliest gynecologic cancer. Standard treatments for advanced stage high-grade serous ovarian cancer, the most common type, include (1) primary cytoreductive surgery (PCS) followed by adjuvant chemotherapy or (2) neoadjuvant chemotherapy (NACT) with interval debulking surgery. Patients in whom PCS is unlikely to yield optimal cytoreduction to no visible residual disease (R0) or who have medical contraindications to PCS are recommended to undergo NACT. Previous studies on associations between environmental factors and risk of any macroscopic residual disease have yielded inconsistent results. We aimed to (1) comprehensively examine the associations between demographic, lifestyle and reproductive factors and risk of residual disease after PCS; and (2) develop and internally validate a risk prediction model based on these factors.

Methods: We used pooled data on 3,492 women who had PCS following a diagnosis with advanced stage high-grade serous ovarian, fallopian tube or primary peritoneal cancers from the Ovarian Cancer Association Consortium. Fifteen exposures of interest included age at diagnosis, menopausal status, race/ethnicity, education level, first-degree family history of ovarian cancer, endometriosis, smoking, body mass index, parity, incomplete pregnancy, tubal ligation, use of combined oral contraceptives, depot-medroxyprogesterone acetate, estrogen (ET), and combined estrogen-progestin therapy. We fit logistic regression models to examine each exposure-residual disease association in 80% of the data (n=2,794; random selection of participants). We developed a risk prediction model including the factors with p-values ≤0.2. Area under the receiver operating characteristic curve (AUC) was used to assess the model’s discrimination in the remaining 20% of the data (n=698).

Results: Of the 3,492 participants, 2,003 (57%) had residual disease following PCS. Older age at diagnosis was associated with an increased risk of residual disease (OR=1.07 per five years, 95% CI 1.03-1.11). In contrast, a family history of ovarian cancer (OR=0.63, 95% CI 0.42-0.95) or ET use for 5+ years (OR=0.61, 95% CI 0.39-0.96) were associated with achieving R0. These above factors were included in the risk prediction model as were race/ethnicity, personal history of endometriosis, and smoking, whose p-values ≤0.2. The model showed modest performance in the validation set (AUC=0.64).

Conclusions: Younger age at diagnosis, family history of ovarian cancer, and long-term ET use were associated with achieving R0 following PCS. Future studies incorporating genetic and clinical factors to improve the risk prediction for residual disease following PCS are warranted.

Citation Format: Minh Tung Phung, Andrew Berchuck, Ellen L. Goode, Marc T. Goodman, Gillian E. Hanley, Jean Richardson, Bronwyn Grout, Anne Chase, Cindy McKinnon Deurloo, Beth Y. Karlan, Toon Van Gorp, Keitaro Matsuo, Karen McLean, Malcolm C. Pike, Joellen M. Schildkraut, Kathryn L. Terry, Anna DeFazio, Penelope M. Webb, Paul D. P. Pharoah, Susan J. Ramus, Celeste Leigh Pearce. Environmental factors associated with residual disease after ovarian cancer primary cytoreduction surgery [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2248.

Reproductive Factors Do Not Influence Survival with Ovarian Cancer

BACKGROUND

Previous studies on the association between reproductive factors and ovarian cancer survival are equivocal, possibly due to small sample sizes.

METHODS

Using data on 11,175 people diagnosed with primary invasive epithelial ovarian, fallopian tube, or primary peritoneal cancer (ovarian cancer) from 16 studies in the Ovarian Cancer Association Consortium (OCAC), we examined the associations between survival and age at menarche, combined oral contraceptive use, parity, breastfeeding, age at last pregnancy, and menopausal status using Cox proportional hazard models. The models were adjusted for age at diagnosis, race/ethnicity, education level, and OCAC study and stratified on stage and histotype.

RESULTS

During the mean follow-up of 6.34 years (SD = 4.80), 6,418 patients passed away (57.4%). There was no evidence of associations between the reproductive factors and survival among patients with ovarian cancer overall or by histotype.

CONCLUSIONS

This study found no association between reproductive factors and survival after an ovarian cancer diagnosis.

IMPACT

Reproductive factors are well-established risk factors for ovarian cancer, but they are not associated with survival after a diagnosis of ovarian cancer.

High Prediagnosis Inflammation-Related Risk Score Associated with Decreased Ovarian Cancer Survival

BACKGROUND

There is suggestive evidence that inflammation is related to ovarian cancer survival. However, more research is needed to identify inflammation-related factors that are associated with ovarian cancer survival and to determine their combined effects.

METHODS

This analysis used pooled data on 8,147 women with invasive epithelial ovarian cancer from the Ovarian Cancer Association Consortium. The prediagnosis inflammation-related exposures of interest included alcohol use; aspirin use; other nonsteroidal anti-inflammatory drug use; body mass index; environmental tobacco smoke exposure; history of pelvic inflammatory disease, polycystic ovarian syndrome, and endometriosis; menopausal hormone therapy use; physical inactivity; smoking status; and talc use. Using Cox proportional hazards models, the relationship between each exposure and survival was assessed in 50% of the data. A weighted inflammation-related risk score (IRRS) was developed, and its association with survival was assessed using Cox proportional hazards models in the remaining 50% of the data.

RESULTS

There was a statistically significant trend of increasing risk of death per quartile of the IRRS [HR = 1.09; 95% confidence interval (CI), 1.03-1.14]. Women in the upper quartile of the IRRS had a 31% higher death rate compared with the lowest quartile (95% CI, 1.11-1.54).

CONCLUSIONS

A higher prediagnosis IRRS was associated with an increased mortality risk after an ovarian cancer diagnosis. Further investigation is warranted to evaluate whether postdiagnosis exposures are also associated with survival.

IMPACT

Given that pre- and postdiagnosis exposures are often correlated and many are modifiable, our study results can ultimately motivate the development of behavioral recommendations to enhance survival among patients with ovarian cancer.

Abstract 794: Trends of ovarian cancer incidence by histotype and race/ethnicity in the U.S.: 1992-2017

Background: Ovarian cancer incidence rates in the U.S. decreased since the early 1970s, which was largely attributed to increasing parity among birth cohorts through 1935 and the introduction of combined oral contraceptives (COCs) in the 1960s. However, COC use prevalence has dramatically declined among 20-34 year-olds since the early 2000s as has parity. Ovarian cancer histotypes share many risk factors, including parity and COC use, but the magnitude of the effects differs by histotype. In addition, the prevalence of these risk factors differs by race/ethnicity. Understanding the trends in ovarian cancer incidence by histotype and race/ethnicity will allow us to consider the impact of changes in risk factor profiles.

Methods: Ovarian cancer incidence rates in 1992-2017 were obtained from the Surveillance, Epidemiology, and End Results (SEER) 13 registry. Age-standardized ovarian cancer incidence trends for the three most common histotypes (high-grade serous (HGS), endometrioid and clear cell) and four racial/ethnic groups (Hispanic, Asian/Pacific Islander (API), non-Hispanic Black (NHB), and non-Hispanic White (NHW)) were analyzed using joinpoint regression. Temporal trends of each histotype were analyzed using age-period-cohort models.

Results:

Joinpoint regression analysis: NHW had the highest incidence rates for HGS and endometrioid cancers, while API had the highest rate for clear cell cancer. HGS cancer incidence declined in all racial/ethnic groups during 1992-2017; NHW had the greatest reduction. Endometrioid cancer incidence decreased in NHW and NHB but increased in Hispanics in recent years. All racial/ethnic groups showed an increasing trend of clear cell cancer incidence.

Age-period-cohort analysis: HGS cancer incidence has been decreasing in NHW and API by birth cohort, but not in NHB or Hispanics. There is a decreasing trend in HGS cancer incidence by period in NHW, but no clear period-specific pattern was observed among other racial/ethnic groups. Endometrioid cancer incidence has been decreasing in NHW and API, but increasing in NHB and Hispanics in recent cohorts. Clear cell cancer incidence has been increasing by birth cohort in all racial/ethnic groups.

Conclusions: HGS and endometrioid cancer incidence has been decreasing overall, but clear cell cancer incidence has been increasing. This may be due to an improvement in diagnosis with a shift from classifying “carcinoma, not otherwise specified” to clear cell cancer. It is also possible that the impact of shifting patterns of lower COC use and parity are having a bigger impact on clear cell cancer given that these exposures are more protective for this histotype. Further, the introduction of opportunistic salpingectomy may balance any impact of COC use or parity changes for HGS cancer. There are differences in the ovarian cancer incidence trends by histotype and race/ethnicity, highlighting the impact of different preventive strategies.

Citation Format: Minh Tung Phung, Celeste Leigh Pearce, Rafael Meza, Jihyoun Jeon. Trends of ovarian cancer incidence by histotype and race/ethnicity in the U.S.: 1992-2017 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 794.

Expanding Our Understanding of Ovarian Cancer Risk: The Role of Incomplete Pregnancies

BACKGROUND

Parity is associated with decreased risk of invasive ovarian cancer; however, the relationship between incomplete pregnancies and invasive ovarian cancer risk is unclear. This relationship was examined using 15 case-control studies from the Ovarian Cancer Association Consortium (OCAC). Histotype-specific associations, which have not been examined previously with large sample sizes, were also evaluated.

METHODS

A pooled analysis of 10 470 invasive epithelial ovarian cancer cases and 16 942 controls was conducted. Odds ratios (ORs) and 95% confidence intervals (CIs) for the association between incomplete pregnancies and invasive epithelial ovarian cancer were estimated using logistic regression. All models were conditioned on OCAC study, race and ethnicity, age, and education level and adjusted for number of complete pregnancies, oral contraceptive use, and history of breastfeeding. The same approach was used for histotype-specific analyses.

RESULTS

Ever having an incomplete pregnancy was associated with a 16% reduction in ovarian cancer risk (OR = 0.84, 95% CI = 0.79 to 0.89). There was a trend of decreasing risk with increasing number of incomplete pregnancies (2-sided Ptrend < .001). An inverse association was observed for all major histotypes; it was strongest for clear cell ovarian cancer.

CONCLUSIONS

Incomplete pregnancies are associated with a reduced risk of invasive epithelial ovarian cancer. Pregnancy, including incomplete pregnancy, was associated with a greater reduction in risk of clear cell ovarian cancer, but the result was broadly consistent across histotypes. Future work should focus on understanding the mechanisms underlying this reduced risk.

Depot-Medroxyprogesterone Acetate Use Is Associated with Decreased Risk of Ovarian Cancer: The Mounting Evidence of a Protective Role of Progestins

BACKGROUND

Combined oral contraceptive use is associated with a decreased risk of invasive epithelial ovarian cancer (ovarian cancer). There is suggestive evidence of an inverse association between progestin-only contraceptive use and ovarian cancer risk, but previous studies have been underpowered.

METHODS

The current study used primary data from 7,977 women with ovarian cancer and 11,820 control women in seven case-control studies from the Ovarian Cancer Association Consortium to evaluate the association between use of depot-medroxyprogesterone acetate (DMPA), an injectable progestin-only contraceptive, and ovarian cancer risk. Logistic models were fit to determine the association between ever use of DMPA and ovarian cancer risk overall and by histotype. A systematic review of the association between DMPA use and ovarian cancer risk was conducted.

RESULTS

Ever use of DMPA was associated with a 35% decreased risk of ovarian cancer overall (OR, 0.65; 95% confidence interval, 0.50-0.85). There was a statistically significant trend of decreasing risk with increasing duration of use (P _trend < 0.001). The systematic review yielded six studies, four of which showed an inverse association and two showed increased risk.

CONCLUSIONS

DMPA use appears to be associated with a decreased risk of ovarian cancer in a duration-dependent manner based on the preponderance of evidence. Further study of the mechanism through which DMPA use is associated with ovarian cancer is warranted.

IMPACT

The results of this study are of particular interest given the rise in popularity of progestin-releasing intrauterine devices that have a substantially lower progestin dose than that in DMPA, but may have a stronger local effect.

Abstract 3498: Ovarian cancer risk factors multiply to create high risk in pre-menopausal women

Background: Ovarian cancer is the eighth-most common cancer among women. Although a number of established risk factors exist for this disease, analyses of these exposures have largely not taken into account potential interactions. We present an interaction analysis of eight ovarian cancer risk factors, followed by the creation of modifiable and non-modifiable risk scores for the disease.

Methods: Data used in this analysis come from nine studies in the Ovarian Cancer Association Consortium (OCAC): one from Australia, one from Europe and seven from the US. Analyses were restricted to pre-menopausal women without first-degree family histories of ovarian cancer, leading to a final study population of 1504 cases and 3515 controls. Five potentially modifiable predictors (oral contraceptive (OC) use duration, body mass index, tubal ligation, hysterectomy and breastfeeding) and three non-modifiable predictors (parity, incomplete pregnancies and history of endometriosis) were considered. A complete analysis of interactions between the eight variables as well as with age, race/ethnicity, education level and study site was conducted. No statistically significant pairwise interactions were found with likelihood ratio statistics, thus suggesting no departure from multiplicativity in the odds ratios. The modifiable and non-modifiable risk scores were calculated as the product of the odds ratios for each group of exposures. Logistic regression was used to model the association between ovarian cancer and the risk scores. Age, race/ethnicity, education level and study site were included in the model.

Results: The associations between the second, third and fourth quartiles of the modifiable risk score compared to the lowest quartile were 1.67 (95% CI 1.35-2.09), 2.18 (95% CI 1.76-2.71) and 3.72 (95% CI 3.04-4.57), respectively. The odds ratios for the non-modifiable risk score were 1.17 (95% CI 0.95-1.44), 1.24 (95% CI 0.99-1.54) and 2.06 (95% CI 1.68-2.53), respectively for the second, third and fourth quartiles compared to the first. Women in the highest quartiles of both the modifiable and non-modifiable risk scores, representing 14.6% of the women, had a 7.67-fold increased risk of ovarian cancer (95% CI 4.68-11.39) compared to women in the lowest quartiles for both risk scores (3.6% of the women).

Conclusions: Pre-menopausal women in the highest risk quartiles have a substantially elevated risk of ovarian cancer based on these eight exposures. Modifiable factors contribute more than non-modifiable factors to ovarian cancer risk among pre-menopausal women with no family history in our study. Women in the highest risk group (fourth quartile of both risk scores) could reduce their risk by intervening on the modifiable exposures; for example, 63% of women in this group had not used oral contraceptives and 93% had not had tubal ligation. However, careful consideration of the risks and benefits of such prevention measures is needed.

Citation Format: Minh Tung Phung, Bhramar Mukherjee, Alice W. Lee, Penelope M. Webb, Harvey A. Risch, Jennifer Anne Doherty, Holly R. Harris, Marc T. Goodman, Roberta B. Ness, Francesmary Modugno, Allan Jensen, Susanne K. Kjaer, Kathryn L. Terry, Daniel W. Cramer, Argyrios Ziogas, Hoda Anton-Culver, Malcolm C. Pike, Anna H. Wu, Celeste Leigh Pearce. Ovarian cancer risk factors multiply to create high risk in pre-menopausal women [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3498.

Abstract B38: Use of progestin-only injectable contraceptive is associated with reduced risk of ovarian cancer in the Ovarian Cancer Association Consortium

Background: Combined oral contraceptive use is associated with a decreased risk of ovarian carcinoma (cancer). However, the relationship between progestin-only contraceptives and ovarian cancer risk is unclear. Two previous studies have suggested a protective effect whereas another reported a non-statistically significant increased risk of ovarian cancer. The current study examined the association between use of depot medroxyprogesterone acetate (DMPA), a progestin-only injectable contraceptive, and ovarian cancer risk, using data from seven case-control studies participating in the Ovarian Cancer Association Consortium (OCAC).

Methods: A pooled analysis examining the relationship between DMPA use and ovarian cancer risk was conducted using 7,679 invasive ovarian cancer cases and 11,136 controls from six studies from the United States and one from Australia. Combined oral contraceptive use, parity, education level, age, and race/ethnicity were considered important a priori confounders and were included in all statistical models. OCAC study site was also included in all models. The impact of additional exposures, including a personal history of endometriosis, first-degree family history of ovarian cancer, tubal ligation, breastfeeding, body mass index, and menopausal hormonal therapy use on the association between DMPA use and ovarian cancer were considered. None of these variables was found to impact the DMPA use-ovarian cancer association by &gt;10% and thus not included in the final models. Odds ratios (OR) and 95% confidence intervals (CI) were generated from logistic regression models. The association between duration of DMPA use, categorized as never use, &lt;2 years of use, and 2+ years of use, and ovarian cancer risk was examined in the two studies that had this information available.

Results: The frequency of DMPA use among controls ranged from 1.25% to 3.53% across the seven studies. DMPA use was more common in controls than in cases in all of the studies. Overall, ever use of DMPA was associated with a 26% decreased risk of ovarian cancer (95% CI 0.58-0.94), after taking into account combined oral contraceptive use, parity, education level, age, race/ethnicity, and OCAC study site. A significant trend with duration of use was observed in the two studies with these data (p=0.02).

Conclusions: DMPA use appears to be associated with a decreased risk of ovarian cancer. The finding provides additional evidence that progestins may be protective for ovarian cancer. Further evaluation of the role of DMPA as a potential primary prevention strategy for ovarian cancer, especially in women for whom combined oral contraceptive use is contraindicated due to concerns about estrogen-induced thromboembolic events, is warranted.

Citation Format: Minh Tung Phung, Penelope M. Webb, Jennifer Anne Doherty, Holly R. Harris, Pamela J. Thompson, Marc T. Goodman, Kirsten Moysich, Francesmary Modugno, Roberta B. Ness, Joellen M. Schildkraut, Andrew Berchuck, Daniel W. Cramer, Kathryn L. Terry, Linda Titus, Alice W. Lee, Malcolm C. Pike, Anna H. Wu, Celeste Leigh Pearce. Use of progestin-only injectable contraceptive is associated with reduced risk of ovarian cancer in the Ovarian Cancer Association Consortium [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr B38.

Prognostic models for breast cancer: a systematic review

BACKGROUND

Breast cancer is the most common cancer in women worldwide, with a great diversity in outcomes among individual patients. The ability to accurately predict a breast cancer outcome is important to patients, physicians, researchers, and policy makers. Many models have been developed and tested in different settings. We systematically reviewed the prognostic models developed and/or validated for patients with breast cancer.

METHODS

We conducted a systematic search in four electronic databases and some oncology websites, and a manual search in the bibliographies of the included studies. We identified original studies that were published prior to 1st January 2017, and presented the development and/or validation of models based mainly on clinico-pathological factors to predict mortality and/or recurrence in female breast cancer patients.

RESULTS

From the 96 articles selected from 4095 citations found, we identified 58 models, which predicted mortality (n = 28), recurrence (n = 23), or both (n = 7). The most frequently used predictors were nodal status (n = 49), tumour size (n = 42), tumour grade (n = 29), age at diagnosis (n = 24), and oestrogen receptor status (n = 21). Models were developed in Europe (n = 25), Asia (n = 13), North America (n = 12), and Australia (n = 1) between 1982 and 2016. Models were validated in the development cohorts (n = 43) and/or independent populations (n = 17), by comparing the predicted outcomes with the observed outcomes (n = 55) and/or with the outcomes estimated by other models (n = 32), or the outcomes estimated by individual prognostic factors (n = 8). The most commonly used methods were: Cox proportional hazards regression for model development (n = 32); the absolute differences between the predicted and observed outcomes (n = 30) for calibration; and C-index/AUC (n = 44) for discrimination. Overall, the models performed well in the development cohorts but less accurately in some independent populations, particularly in patients with high risk and young and elderly patients. An exception is the Nottingham Prognostic Index, which retains its predicting ability in most independent populations.

CONCLUSIONS

Many prognostic models have been developed for breast cancer, but only a few have been validated widely in different settings. Importantly, their performance was suboptimal in independent populations, particularly in patients with high risk and in young and elderly patients.

Construction of attenuated HIV-1 accessory gene immunization cassettes

Delivery of genetic expression cassettes into animals can effectively induce both humoral and cellular immunity to the expressed gene product. Previously, we used this strategy to immunize against HIV-1 structural and enzymatic proteins in mice, non-human primates and in humans. In contrast, the use of the accessory genes including vif, vpr, vpu and nef as immunotherapeutic vaccine targets has not been well characterized. Our goal is to design an effective genetic HIV vaccine, which includes the accessory genes as part of a multi-component immunogen. In order to develop accessory genes as genetic vaccines, we have molecularly cloned and analysed the sequence variation and immunogenic potential present in these genes derived from viral isolates obtained from HIV-1 infected patients and laboratory isolates. Prototype genetic variants were selected and their ability to induce humoral and cellular immune responses was studied in animal models. We observed that attenuated accessory genes can effectively induce both humoral and cellular responses in mice and the resulting immune response is directly correlated with DNA concentrations delivered and the number of boosts. This strategy can be used generally to develop an effective, safe DNA vaccine for any pathogen.

HIV-1 viral protein R (Vpr) as a regulator of the target cell

Among the putative 'accessory genes' of HIV-1, the 96 amino acid virion-associated Vpr gene product has been described to have several novel biological activities. These include cytoplasmic-to-nuclear translocation thus empowering HIV to infect and replicate in nondividing cells and to function to increase viral replication, particularly in monocytes. Along with these viral effects, we describe the dramatic biological changes induced by HIV-1 Vpr in the target cells of HIV infection including induction of changes in transcriptional patterns and complete inhibition of proliferation which collectively is termed differentiation. These changes occur in the absence of other viral gene products and suggest that Vpr mediates its proviral effects partially or perhaps solely through modulation of the state of the target cell rather than directly on the virus. The inhibition of proliferation in T-cell lines has been proposed by several groups to demonstrate that the inhibition of proliferation specifically arrests the cell cycle further supporting the notion that Vpr activity is directed at cellular targets. We have recently described a role for Vpr in modulating the glucocorticoid pathway, a pathway involved in the regulation of the state of the cell in cytoplasmic-to-nuclear translocation and in the modulation of host cell transcription. Importantly, certain antiglucocorticoids have been shown to modulate Vpr activity in vitro. These results demonstrate that the cell contains specific receptor(s) molecule(s) through which Vpr mediates its activity and that these molecules have implications for cell biology in general. These results collectively demonstrate that Vpr represents a unique target for anti-HIV drug development and has significance for HIV-1 disease progression.