Breast cancer in women below 40 reported to Sultan Qaboos Cancer Care Comprehensive Center: 20 Years Retrospective cohort study

Breast cancer is considered a public health concern worldwide, as in 2020, 11.7% of all cancers diagnosed in the world were female breast cancer, making it the most common cancer reported around the globe¹. Breast cancer is responsible for roughly 15% of all cancer deaths among women worldwide². Breast cancer incidence in Oman is increasing. In 2010, breast cancer was the most common cancer diagnosed in Oman, comprising 22.36% of cancers among women, and mostly reported in women aged 40-59 years³.

The statistics shows that 27.5% of breast cancer affect Omani women aged below 40 years³. These figures are similar to other countries in the region⁴.  Breast cancer in young women (below 40) has not been studied in Oman, for which, this study was conducted. Also, to understand the histological and molecular pattern of BC in this age group, as well as to estimate the overall (OS) survival of these patients.

We conducted a retrospective cohort study. Electronic data was collected from women aged 40 and below treated at Sultan Qaboos Cancer Care Comprehensive Center (SQCCCRC), from 2002-2022. Secondary data for socio-demographics, family history of BC, BC histological subtypes, immunohistochemistry (PR, ER, and HER2), and TNM staging were collected. A total of 418 patients were included in the study. SPSS was used to analyze the data. Appropriate statistical tests were used for descriptive and inferential analysis. The Kaplan-Meier estimator and log-rank test were used for the survival analysis. Differences were considered statistically significant at p-value < 0.05.

Our study showed that the mean age at the time of diagnosis was (34.7 ±4.3 years), with a mean BMI of (28. 47±6.6). 16.7% of patients had a positive family history of BC. Ductal carcinoma was the most common one found.

We also found that the majority of patients in our study tested positive for PR and ER (62%, and 70%), and 42% tested positive for HER2. Similarly, 38.4 % reported negative PR, 30% negative ER and 57.8% negative HER2.

We examined the potential factors that may affect the OS in these patients and found that: ER was a significant predictor of OS. Also, PR was a significant predictor for the OS and HER2 is a significant predictor also. TNM staging categorized as early, locally advanced, and metastatic was also a significant predictor of OS. As all these factors have a p-value < 0.05.

We compared our findings with the neighboring countries (GCC), Asian countries (India) and a well-developed country (Norway).  We reached to a conclusion that the pathological characteristics of BC in Omani women could be similar to neighboring countries (like Saudi Arabia), but different from other Asian (e.g., India) and European countries (e.g., Norway). 

 This study found that most of the Omani women aged 40 and below reported to SQCCCRC with breast cancer were positive ER and PR but negative HER2 status receptors. At reporting, most of the women were at an advanced stage and ductal cancer as per the histochemistry. Receptor status (ER, PR) and TNM staging were significant predictors of OS in Omani women diagnosed with breast cancer under or at the age of 40 years.

Table 1: survival analysis of BC patients <=40 years old, Overall survival (OS) predicted by Receptor status (ER, PR, HER2), family history, and disease stages.

References:

1. Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, et al. Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. CA Cancer J Clin. 2021 May;71(3):209–49.

2. Department of Non-Communicable Diseases Surveillance and control Directorate General of Health Affairsand. Early Detection & Screening for Breast Cancer, Operational Guidelines, First Edition 2010, Department of family and community health directorate general of health affair, Ministry of Health, Oman [Internet]. MOH, Oman; 2010 [cited 2023 Dec 26]. Available from: https://www.moh.gov.om/documents/272928/1314763/Operational+and+managem…

3. Department of Non-Communicable Diseases Directorate General of Primary Health Care. Definitions, Cancer Incidence in Oman 2019, Department of Non-Communicable Diseases Directorate General of Primary Health Care, MOH, Oman [Internet]. MOH, Oman; Available from: https://www.moh.gov.om/documents/272928/1232802/Cancer+Incidence+In+Oma…

4. Al-thoubaity FK. Molecular classification of breast cancer: A retrospective cohort study. Annals of Medicine and Surgery. 2020 Jan 1;49:44–8.

5. Dinesh Chandra Doval1,3*, Anila Sharma2, , Rupal Sinha3, , Kapil Kumar4, , Ajay, Kumar Dewan4, , Harit Chaturvedi5, et al. Immunohistochemical Profile of Breast Cancer Patients at a  Tertiary Care Hospital in New Delhi, India [Internet]. Asian Pacific Journal of Cancer Prevention, Vol 16, 2015; 2015. Available from: https://pubmed.ncbi.nlm.nih.gov/26163622/