Abstract 879: Validation of the Nigerian Breast Cancer Study model for predicting individual breast cancer risk in Cameroon and Uganda
Authors: Ashi Kevin , Ndom Paul , Gakwaya Antony , Makumbi Timothy , Olopade Olufunmilayo I. , Huo Dezheng 
Published: July 2021

Abstract
Background: Women of African ancestry across the diaspora have low risk of developing breast cancer compared to women of European ancestry. However, they suffer the highest mortality rates because of the disproportionate burden of young onset aggressive hormone receptor negative breast cancer. To implement strategies for early detection and prevention, it is critically important to develop better risk assessment tools. The Nigerian Breast Cancer Study (NBCS) model is a new risk assessment tool developed for the individual estimation of absolute risk of invasive breast cancer in Nigeria. Its applicability outside of Nigeria remains uncertain as it has not been validated in other Sub-Sahara African (SSA) populations.
Methods: We conducted a case-control study among women with breast cancer and controls ascertained in Cameroon and Uganda from 2011 to 2016. Structured questionnaire interviews were performed to collect demographic and reproductive characteristics. The NBCS model, the Gail model for white population, the Gail model for Black population (CARE), and the Black Women's Health Study (BWHS) model were applied to the Cameroon and Uganda samples separately. Local incidence rates were incorporated into the NBCS model for the Uganda analysis. Receiver-Operating Characteristic (ROC) analyses were performed and the area under ROC curve was used to indicate discriminating capacity.
Results: The cohort included 549 cases (mean age 47 ± 11.94) and 509 Controls (mean age 46 ± 11.68). Compared to the other three models, the NBCS model performed best in both countries. The discriminating accuracy of the NBCS model in Cameroon (age-adjusted C-index = 0.599, 95% CI 0.540-0.658) was significantly better than in Uganda (age-adjusted C-index = 0.511, 95% CI, 0.437-0.585). In Cameroon, the BWHS model had slightly lower distinguishing ability (age-adjusted C-index = 0.588, 95% CI, 0.528-0.647) and gave lower risk estimates in cases than the NBCS model. The Gail and CARE models performed poorly in both countries.
Conclusions: These findings demonstrate the potential clinical utility of the NBCS model for risk assessment in Cameroon. All currently available models performed poorly in Uganda, which suggests that the NBCS model may need further calibration before use in other regions of Africa. Differences in risk profiles across the African diaspora underscores the need for larger studies and may require development of country or region-specific risk assessment tools for breast cancer.
Citation Format: Kevin Ashi, Paul Ndom, Antony Gakwaya, Timothy Makumbi, Olufunmilayo I. Olopade, Dezheng Huo. Validation of the Nigerian Breast Cancer Study model for predicting individual breast cancer risk in Cameroon and Uganda [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 879.