October is Breast Cancer Awareness Month, an annual international campaign aimed to increase education and raise funds for further research into breast cancer. Breast cancer is the most common type of cancer in women worldwide, with at least 2.1 million women affected each year. In 2018, the World Health Organization (WHO) estimated that breast cancer accounted for 15% of all cancer deaths in women. Breast cancer occurs most commonly in women ages 50 years and older who have been through menopause, although younger women and men can also get the disease. Risk factors include a family history of breast cancer, genetic mutations, and lifestyle factors such as smoking and being overweight or obese. With increased awareness of breast cancer and its risk factors, cases can be diagnosed earlier or possibly even prevented. The most common type of non-invasive breast cancer is ductal carcinoma in situ (DCIS), where abnormal cells have been found but have not become malignant. Identifying breast cancer cases in the earlier stages means patients have a better chance of successful treatment and survival.
In Figure 1 below, GlobalData epidemiologists have highlighted the incidence rates of DCIS in women ages 18 years and older across the eight major pharmaceutical markets (8MM) (US, France, Germany, Italy, Spain, UK, Japan, and urban China) in 2020. The highest incidence rate was reported in the US with 40.51 cases per 100,000 population, while the lowest incidence rate was reported in urban China with 1.44 cases per 100,000 population. The differences between these two markets can be attributed to the lack of population-based screening programs and funding in urban China. In the US, the American Cancer Society recommends all women ages 45–54 years to have an annual mammogram, and for those ages 54 years and older to either continue receiving yearly mammograms or switch to one mammogram every two years. Although similar recommendations for breast cancer screening are made in urban China, participation rates are much lower than in the US.
If DCIS is left untreated, cancer cells may develop and spread to the surrounding tissues. Therefore, diagnosing more people at this initial stage is vital to prevent the development of aggressive breast cancer, which is more difficult to treat. Early detection is made possible through regular self-breast exams, clinical breast exams, and mammograms. The goal of promoting these methods for detecting breast cancer is to identify cases before they have developed to more advanced stages. In settings where healthcare systems are limited and screening programs using mammograms are not cost-effective, early diagnosis programs aimed at self-checking for signs and symptoms need to be introduced instead.
Figure 1: Diagnosed Incidence of Non-Invasive DCIS (Cases per 100,000 Population), 8MM, Ages ≥18 Years, Women, 2020.