Individualized Screening for Breast Cancer

Introduction:

Breast cancer is common cancer occurring in women, and when untreated, it can be fatal too. Hence, early detection and management are important. It can be done through personalized or individualized screening based on certain criteria, like risk-based screening, age, and type of screening exam. The personalized screening will require an accurate estimation of individual risk, age, family history of breast or ovarian cancer, breast density, reproductive history, previous benign breast disease, hormonal factors, lifestyle, and a combination of common genetic variants. The genetic variants include BRCA and single-nucleotide polymorphisms (SNPs) or other susceptibility genes. The inclusion of artificial intelligence in breast-cancer risk assessment has been helpful for short-term risk estimation.

What Are the Screening Tools Available for Breast Cancer?

Mammography is the screening tool of choice for doctors when screening for breast cancer. Mammography also has its drawbacks, including the requirement of additional testing and the possibility of false positive and false negative results. There is an incidence of false negative results from mammograms of about 10 % to 15 % of the time. Digital mammography is the best tool to identify breast cancers in the case of dense breasts. An innovation of the mammogram, known as tomosynthesis or 3D mammography will enable the finding of small cancers, and it also help reduce the need for additional or repeat tests due to false-positive results. There is a risk in this also, overdiagnosis, in which there will be a breast problem that would not lead to any unwanted outcomes, yet there will be overtreatment.

There are other diagnostic options such as ultrasound and MRI (magnetic resonance imaging), which are less frequently used, as they barely benefit women who are of average risk. Though it is beneficial in women with high-risk, women with dense breasts, and those who have a lump or mass in the breast. Ultrasound and MRI use is not reduced as there are more false-positive results. The American Cancer Society (ACS) states that women with BRCA gene mutations, women with a strong family history of breast cancer, and those with previous radiation therapy to the chest are candidates for screening, and they should consider mammography and MRI every year. Women who are at moderate risk, such as those with precancerous changes in their biopsy should also consider screening.

What Are the Initiatives for Individualized Screening for Breast Cancer?

The Breast Cancer Surveillance Consortium (BCSC) is the most widely used risk-estimation model. It was developed by Tice et al. in 2008. For estimating the risk, factors like age, ethnicity, breast density, race, family history of breast cancer, and previous biopsy are taken into consideration. The previous biopsy factor was replaced by benign breast disease type in 2015. Including the polygenic risk score (PRS) has helped improve the accuracy of the model, and this was found by Yanes et al. The Breast Cancer Surveillance Consortium risk model is also used for personalized screening and includes age, ethnicity or race, history of benign breast disease, first-degree relatives with breast cancer, and mammographic breast density. This is combined with the Catalan (people of Spain) breast cancer incidence and mortality based on the cause of death and the distribution of risk factors in the BCSC dataset. These were implemented for the estimation of a preliminary five-year absolute risk of breast cancer. After obtaining the risk score, the subsequent second visit by the same healthcare professional as the first visit will be scheduled for screening recommendations, and risk communication is done.

How Is Breast Cancer Screening Done in Different Countries?

In Spain, the majority of the population-based screening programs are targeted at older women in the age range of 50 to 69 years. In younger women, opportunistic screening is done. In this screening, false positive results and overdiagnosis can happen to younger women. To overcome this, low-risk women are asked to wait and high-risk women are screened first.

Women who have anomalous findings in mammograms and those with high-risk breast cancer are referred to public healthcare centers. There is no watch or recommendation for women over 50 years of age, as they alter access to these public health centers once every two years.

BreastScreen Singapore is a nationwide mammography screening program that was established in 2002. It helps women who are around 50 to 69 years of age to participate in the early detection of breast cancer. There will be a biennial screening, and only 66 % of the target group participated according to a survey.

What Are the Established Risk Factors for Breast Cancer?

1. Aging: With increased age there is an increased incidence of breast cancer. It is significant in women above the age of 50 years.

2. Family History: A family history of cancer in first-degree relatives that have been affected with breast or ovarian cancer.

3. Reproductive History: Women who have had early menses such as before 12 years of age and women who have had late menopause after 55 years of age are estimated to have a high risk.

4. Breast Biopsy: Prior bracelets biopsy revealing atypical ductal hyperplasia.

5. Genes: Errors in genes like BRCA1, BRCA2, CHEK2, PALB2, and others.

What Are the Recent Developments in the Individualized Breast Screening Program?

The tomosynthesis mammographic imaging screening trial (TMIST) is progressing to evaluate if 2D or 3D screening technologies are necessary to better diagnose cancer. It is supported by the NCI Community Oncology Research Program. There is another upcoming screening study known as WISDOM (Women Informed to Screen Depending on Measures of Risk). This study is an individualized risk assessment tool to check for genetic testing in each woman. Mammography identifies women only based on factors that increase their risk, such as age and prior family history. This WISDOM study helps screen women based on a wide spectrum of diseases.

Conclusion:

Early screening has led to a decrease in the mortality of women affected with breast cancer. Hence there is an unavoidable need for screening in women of risk groups. Before the implementation of individualized screening, clear evidence of the advantages and harms it poses should be established. It is the need of the hour for designing tools and strategies for developing interventions that will primarily focus on increasing awareness about individualized screening and educating on risk measurement.