Abstract and Introduction
Background: The worldwide incidence of invasive breast cancer in women is increasing according to several studies. This increase in incidence seems to be higher in young women (< 40 years). However, the reasons for this trend are poorly understood. This article aims to provide the most recent estimates of this trend and assess whether there is indeed an increase in the incidence of breast cancer among young women to strengthen prevention campaigns.
Methods: We collected data from the Isere cancer registry in France of all invasive breast cancers from January 1990 to December 2018. The standardized incidence rate was calculated for four age groups (< 40 years, 40–49 years, 50–74 years, ≥ 75 years) for this period. The 10-year relative survival was evaluated for each age group age for two periods (1990–1999 and 2000–2008). From 2011 to 2013, we analyzed the incidence and 5-year relative survival by tumor subtype (triple negative, luminal, HER2 amplified) for each age group.
Results: A total of 23,703 cases were selected, including 1343 young women (< 40 years). The incidence of invasive breast cancer increased annually by 0,8% (95% CI 0,7; 1) in all age groups combined from 1990 to 2018. The highest incidence increase is found among young women, by 2,1% annually (95% CI 1,3; 2,8). Regarding tumor subtypes from 2011 to 2018, the incidence of triple negatives increases higher in young women (+ 1,4% by year, 95% CI − 8,2; 11) and those over 75 years (+ 4% by year, 95% CI − 5,1; 13,2), but the results are not statistically significant. 10-year relative survival in young women increased from 74,6% (95% CI 69,6; 78,9) to 78,3%(95% CI 73,7; 82,1) between 1990–1999 and 2000–2008, respectively. Five-year relative survival is better in young women among triple negative and HER2 amplified.
Conclusion: Our study confirms the current trend of increasing the incidence of breast cancer in young women, associated with improved survival very likely attributable to earlier diagnosis due to increased awareness, and improvements in treatment. A better individualized risk-based screening strategy is needed for these patients. Additional studies will be needed to more accurately assess the risk of developing breast cancer and improve diagnostic performance.
Breast cancer (BC) is the most common tumor in women worldwide. It amounted to 25% of all women's cancers globally and constitutes a real public health problem. The age-standardized incidence of BC is highly variable, ranging from < 40/100,000 person-years based on the world standard population (Central and East Asia and Africa) to > 80/100,000 (Australia, North America, and Western Europe). Although its incidence is more important in many developed countries, mortality rates are higher in countries with a low level of development.
The incidence of all cancers is increasing worldwide regardless of age. Concerning BC, the incidence rate is increasing in several Western countries (the USA, Europe, Australia, etc.) for the last three decades.[2,3]
In France, it represents 33% of women's cancer with around 59,000 new cases in 2018. It is the leading cause of cancer death in women closely followed by lung cancer. BC screening programs have been implemented throughout the country since 2004 but started gradually since other 1994. It is recommended only in women aged 50 to 74 years or if there are risk factors such as a family history or a genetic mutation such as BRCA. After an increase in incidence rates between 1990 and 2003, there was a stabilization until 2010 probably due to a diminution in menopausal hormonal prescriptions after 2003 and the screening saturation effect.[7,8] Since this year, the incidence rate is rising (0,6% per year).
Mortality rates have been constantly decreasing over the last three decades (1,3% per year) thanks to therapeutic advances with the earlier diagnostic due to screening.
Among young women (YW), defined by the European consensus treatment guidelines as women aged 40 years or below, there is a significant increase in incidence rates of BC at least since the 1990s in Europe.[9,10] This age group represents 5% of diagnoses in France and 7% worldwide. Nevertheless, except for individuals with a high genetic risk, BC occurring in younger women remains poorly understood. However, recent studies show that lack of physical activity, alcohol, tobacco, age > 30 years of pregnancy, or a history of chest irradiation are several risk factors.[12,13]
The usual presentation of breast cancer in young women (BCYW) is later stages at diagnosis, more aggressive pathological characteristics, a higher rate of triple-negative and HER2-overexpressing tumors, and greater rates of recurrence in comparison with older women.
In France, from 1990 to 2018 incidence rate increased more in YW in comparison with all age groups combined (0,9% vs. 0,6% by year, respectively), but there are no data by histological subtype.
The increase in incidence of BCYW is worrying because the behavior of these tumors is in the majority of cases more aggressive in comparison with older women.
This study aimed to assess the evolution of incidence and the survival rates by tumor subtypes of BC among YW from the year 1990 to 2018 according to data from the registry of the department of Isere in France to improve awareness and prevention campaigns.
Breast Cancer Res. 2022;24(87) © 2022 BioMed Central, Ltd.
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