Breast cancer is a disease in which cells in the breast grow out of control. There are different kinds of breast cancer. The kind of breast cancer depends on which cells in the breast turn into cancer.
- Breast cancer is the most frequently diagnosed cancer among women worldwide.
- Despite the fact that breast cancer is more frequent after fifty years of age, breast cancer among young women has recently drawn particular attention due to an increase in incidence in several western countries.
- With the exception of individuals with a high genetic risk, breast cancer occurring in younger women remains poorly understood.
- This project aims at investigating the patient, tumour and treatment characteristics as well as the long-term health outcomes of these women by evaluating numerous variables that were collected from their pathology and medical files, including the social environment, family history, fertility and pregnancy.
- We constituted a population-based cohort from the Geneva Cancer Registry of 1586 patients with breast cancer who were aged less than 46 years at the time of diagnosis.
- Breast cancer was diagnosed before the age of 35 years in 225 women (14.2%), between 35 and 39 years of age in 368 women (23.2%) and between 40 and 45 years of age in 993 women (62.6%).
- Most of the patients were diagnosed with luminal A or luminal B molecular subtypes (32.8 and 37.5%, respectively), stage I or II tumours (75.2%), and estrogen (74.8%) and progesterone (67.5%) positive receptors.
Luminal A breast cancer is hormone-receptor positive (estrogen-receptor and/or progesterone-receptor positive), HER2 negative, and has low levels of the protein Ki-67, which helps control how fast cancer cells grow. Luminal A cancers are low-grade, tend to grow slowly and have the best prognosis.
Luminal B breast cancer is hormone-receptor positive (estrogen-receptor and/or progesterone-receptor positive), and either HER2 positive or HER2 negative with high levels of Ki-67. Luminal B cancers generally grow slightly faster than luminal A cancers and their prognosis is slightly worse.
- During the study period, 16.7% of these women developed loco-regional recurrences and 25.4% developed distant metastases; the majority (66.3%) did not have a recurrence.
- Regarding mortality, 474 (29.9%) women died during the study period, 347 (73.2%) from breast cancer.
- Breast cancer in young women remains poorly understood.
- Many uncertainties exist in terms of prognostic factors, treatment, recurrence and mortality.
- Uncertainties are even greater in terms of the risks posed by pregnancy during and after breast cancer in this population.
- This project would contribute to the accumulating knowledge on factors that influence the risk of local and distant recurrence and the probability of survival in young women with breast cancer.
- Enhancing understanding of the risks associated with pregnancy during and after breast cancer in this age group is internationally recognized as a research priority.
- The creation of this population-based dataset on breast cancer in young women is envisioned to be the first step towards the constitution of a Swiss Observatory of young breast cancer patients through which the burden of disease, incidence and mortality trends, quality of care, prognostic factors and outcomes can be monitored on an ongoing basis.
The results of this study will help filling the knowledge gap about treatment of young breast cancer patients and having a child after breast cancer, and will provide clinicians and public health professionals’ with additional information to improve quality of care and decrease the impact of breast cancer in young women.