Cancer screening has always been a double-edged sword with both advantages and disadvantages. Although breast cancer screening has been widely available in Western countries since the 1980s and has been effective in reducing mortality rates year after year, the debate about its pros and cons remains unresolved. Although the debate varies from one era to another, initially doubting whether it can reduce the mortality rate, and later blaming the possible damage caused by radiation, in recent years more debates have been made around the comprehensive benefits of screening and overdiagnosis, with different opinions.
According to GLOBOCAN 2008, we are ranked 110th in terms of incidence and 174th in terms of deaths in 184 countries worldwide, and there seems to be no urgency to carry out screening for breast cancer, which is a major consumer of health resources. However, from another perspective, the incidence of breast cancer in China is rapidly increasing at an annual rate of 3.9% (urban) and 6.3% (rural), and it has become the leading malignant tumor among women, especially in rural areas where the death rate is as high as 30%-40%, becoming one of the main causes of rural poverty. The International Union Against Cancer (UICC) believes that breast cancer screening should be carried out to reduce the death rate, and the former Ministry of Health is accordingly including “two cancers” screening in the national basic public health service program. However, breast cancer screening is different from cervical cancer screening, which is a more mature method, so is mammography, the gold standard for screening, applicable in China? How is the target population determined and is the focus on rural or urban areas? What methods are used? How is quality control performed? There are many issues to be considered, such as the organization and financing of screening teams.
Differences between urban and rural areas
Breast cancer is a tumor closely related to the economic standard of living, unlike cervical cancer which is related to human papilloma virus infection. The World Health Organization also uses the incidence of these two cancers as an indicator of a region’s economic development.
In China, the incidence of breast cancer varies with the vast geographical area and the significant difference between urban and rural areas. According to the 2010 Chinese Tumor Registry Annual Report, the annual incidence rate was higher among urban residents (51.24/100,000) than rural residents (19.61/100,000).
According to the principle of conducting cancer screening, the focus of breast cancer prevention should be in urban areas. However, the annual incidence rate in rural areas (6.3%) is higher than in urban areas (3.9%), and the death rate of breast cancer patients in rural areas (31.9%) is higher than in urban areas (20.2%), which is one of the causes of poverty among farmers due to the disease. Therefore, both from a developmental point of view and from the perspective of taking care of vulnerable groups, rural areas should not be neglected, but different measures should be taken.
Varying ages
China’s “two cancers screening” policy is similar to that of breast cancer, with a similar focus on rural areas and an age limit of 60 years. In Beijing, for example, the annual incidence of cervical cancer in women over 60 years of age is only about 5/100,000; this is not the case for breast cancer, where the peak age is about 12 years earlier than in Western countries (50 vs. 62 years), but most breast cancers develop after menopause, with an incidence rate of over 130/100,000 at age 50, and remains high thereafter, even at age 80. Even at the advanced age of 80 years, the incidence rate remains around 100/100,000 (Figure 1).
Therefore, if the screening age is similar to that of cervical cancer, a “one-size-fits-all” approach before 59 years of age would inevitably exclude most breast cancers from screening, which would be inappropriate.
Methods to be examined
Since the 1990s, the breast cancer mortality rate in Western countries has been declining at a rate of 2% per year, a remarkable achievement due to improvements in treatment, but also due to the widespread implementation of mammography-based screening. However, the detection of dense breasts is hampered by the fact that the fibrous glandular tissue of the breast may conceal smaller tumors.
Considering that our women have small and dense mammary glands and a younger age of onset than in the West, it is questionable whether this method is suitable for screening in Eastern women. Even in the United States, 1302 women had to be screened over a period of 10 years to save one case of breast cancer. Therefore, the applicability of screening methods that have worked well in Western countries to China remains to be confirmed.
It’s all about practice
Screening is currently considered to be a comprehensive and wide-ranging topic that cannot be easily evaluated in a short period of time.
In recent years, I have organized several hospitals in China to try mammography combined with ultrasound for female breast cancer screening, and the preliminary results in more than 100,000 women for two years showed that the detection rate was 6.6‰, and 34.8% of early stage breast cancer. Of the more than 70,000 women screened opportunistically, the breast cancer detection rate was as high as 9.2 per 1,000. Of the nearly 40,000 group natural population screened, the detection rate was 2.1 per 1,000, with early breast cancer accounting for 61.7 percent, and young women were better detected by ultrasound than by x-ray for early breast cancer.
On the basis of this work, the government conducted a three-year trial of primary screening by hand and ultrasound for about 2 million people, followed by X-ray screening for those with suspicion, with the aim of exploring a non-invasive screening method suitable for Chinese women. Although the detection rate of breast cancer was 0.5‰, which was not ideal, it was recognized that ultrasound was difficult to meet the screening needs because of its strong dependence on individual detectors and the lack of reliable quality control standards and time-consuming nature of screening in groups, unlike diagnostic examinations in hospitals.
The detection rate of other screening tests, such as the Shanghai textile system’s breast self-examination and manual screening in several regions, is low, which makes it difficult to detect early cases and cannot reduce the death rate.
Therefore, after years of practice in many regions, different units and multiple methods, there is still no ideal breast cancer screening program for our population.
It is important to explore
As mentioned earlier, the incidence of breast cancer is increasing rapidly, and early detection by screening is the hope to stop its damage.
The practice over the years has been to use non-invasive tests for primary screening, and then to fine tune the detection of suspected high-risk subjects, which would be a feasible way to explore. Various screening methods at different levels are being explored both nationally and internationally to compensate for the shortcomings of X-ray, and high hopes are placed on ultrasound. Professor Tarbar, a leading authority, even asserted at the 2011 American League of Breast Centers Annual Meeting that the automated full-volume breast ultrasound system (ABVS) will be the future of breast cancer screening. This device has indeed improved the diagnostic efficacy of ultrasound for breast detection and solved the challenge of quality control of ultrasound. Recently, the FDA has also approved this device for use in combination with mammography for breast cancer screening to improve the detection of mammographically negative breast cancers in dense breast tissue. However, the device is expensive, time-consuming to review (hundreds of films), and its ability to detect carcinoma in situ with only calcified spots is questionable, so its use for screening does not seem to fit the national situation.
In China, the combination of light scattering technology and ultrasound, which integrates anatomical and functional images, has been used to improve the detection rate of breast cancer in dense breast population by strengthening the quality control of ultrasound, and has been tested by several clinical units. It has a high detection rate of breast cancer in this population and may become the main method of primary screening for breast cancer in the Oriental population after extensive practice.
Building a Prevention and Treatment Network
Considering the low incidence rate but high mortality rate in rural areas and the lack of medical resources, it is advisable to establish a regional network centered on the regional central hospital (or county hospital) for primary screening and free screening of women of appropriate age by primary care units, and refer those who are suspicious to higher medical units for further treatment.
According to the experience of Deyang area in Sichuan Province over the past three years, the number of breast cancer cases in Deyang Regional Central Hospital increased from 80 cases before the establishment of the network in 2008 to 244 cases in 2011, and the detection rate of early stage cases (≤ stage I) increased from 6.3% to 25.8%, while the detection rate of stage IV cases decreased from 18.8% to 2.9%. Therefore, the establishment of a regional control network is a good strategy to share medical resources and improve efficiency.
Localization
In view of the fact that China has a large population and different conditions, it is not appropriate to adopt a “one-size-fits-all” approach to breast cancer screening, but to adapt to local conditions in order to get twice the result with half the effort.
Opportunistic screening is applicable to self-selected professional women in large and medium-sized cities, who can go to qualified medical units in different places for breast health examination by hand, ultrasound and X-ray according to the unified operation procedure, plan and standard, and establish a unified breast information file, and the examination cost can be combined with government subsidy.
Group Screening Screening is available for women of age in group units to go to a qualified hospital for age-stratified screening. For those ≤ 44 years old, manual examination and ultrasound examination; for those 45-54 years old, X-ray examination; for those ≥ 55 years old, manual examination and X-ray examination, and once every other year.
Community-based screening is used for group screening in rural areas or community health centers, and can be performed by hand and ultrasound light scattering mammography for initial screening.
In conclusion, breast cancer screening is an extensive systemic project and a good strategy to stop the harm of breast cancer, but it must be explored and practiced continuously with a scientific view of development to establish the best program suitable for our national conditions in order to benefit women effectively.