Breast Cancer Screening

EPIDEMIOLOGY:

Breast cancer is the most common of all cancers in women in industrialized countries.

In France, about 42 000 new cases were diagnosed in 2000, representing almost a doubling in twenty years (21 200 cases in 1980). Its annual crude incidence rate was 138 per 100 000 women. Breast cancer accounts for 36% of all female cancers. The median age is 61 years at diagnosis. Rare before age 30, the incidence increases and knows a peak between 60 and 69 years.

It decreases after 80 years. In France, breast cancer is the leading cause of cancer death in women. Mortality remains generally stable, with about 11 000 deaths in 2000 (8600 in 1980), due both to an earlier diagnosis through screening, that therapeutic progress (Table I and Fig. 1).

SCREENING:

Screening techniques:

The definition of screening is to reduce the severity of the disease and / or improve the evolution in diagnosing lesions of the earliest possible stages. Its implementation requires the use of a review:

– Economically viable;

– Simple and acceptable to the population;

– Reproducible;

– Reliable.

In order to reduce the severity of the disease and / or improve the evolution in diagnosing lesions of the earliest possible stages.

Most epidemiological studies have shown the importance of early diagnosis for breast cancer when the tumor size is less than 1 cm, node-negative, the chances of survival at 5 years is at least 90% while they are less than 55% in case of lymph node involvement (more than three positive nodes). Mammography can detect tumor lesions from an average size of 5 mm (with significant variations depending on the situation of the lesion and breast density), while the average palpation tracks that tumors larger than 1 cm ( corresponding to an average of eight years of evolution).There is a clear correlation between tumor size and in the risk of metastatic extension since it is estimated that about 50% of tumors larger than three inches already metastatic.

Thus, the key in the examination of breast cancer frame is mammography. Indeed, if breast self-examination and clinical examination have the advantage of simplicity and must be taught and practiced, their effectiveness in terms of screening is relatively low. Ultrasound is also not sufficiently effective in detecting small cancers to be used.

Instead, the mammogram is a good review of profitability in terms of screening that is to say, good sensitivity, specificity and positive and negative predictive values. In addition, it allows diagnosis not yet invasive malignant lesions (carcinoma in situ), highlighting in particular breast microcalcifications, the prognosis is excellent after treatment. Under the effect of mammography screening, a reduction of about 30% in mortality from breast cancer after 7-9 years of follow up is clearly demonstrated.

Screening in France:

In breast cancer screening, two systems coexist in France:

– Individual screening. It has the disadvantage of having a poorly measurable benefit in terms of public health. Cost, performance and the extra potential inherent to possible overdiagnosis is misjudged; – Organized screening whose practice was widespread at the national level since 2004 and is a flagship measure of the 2003 Cancer Plan is to provide to a population of patients between 50 and 74 years a mammography screening test to select those with suspicious signs justifying any further investigations.

Patients are thus called by mail to complete their review. It is assumed at 100% and is performed at an authorized radiologist’s choice of the patient. This screening meets predefined quality standards: certified mammography and regularly controlled by the French Agency for the Safety of Health Products (AFSSAPS), justifying qualified radiologists reading of 500 mammograms per year. Any negative plate is read by a second radiologist. If positive, a diagnostic evaluation should be performed for histological confirmation. The report should be expressed according to ACR classification (modified by ANAES) with a result of the action to be taken (Table II).

The results of this testing with a 60% of the population would be in favor of a 30% reduction in mortality from breast cancer, with a positive predictive value of 30% tracking 1 breast cancer every 200 mammograms ( 30% of these cancers will be less than 1 cm).

Recommendations for screening are contained in boxes 1, 2, 3.

Box 1. Recommendations for screening according ANAES (1999-2004)
A mammogram every two years.
Age between 50-69 years:
– Further testing up to 74 years for women previously included in the screening program between 50 and 69 years;
– Screening of women between 40 and 49 is however not currently indicated.
Two implications (external oblique craniocaudal).
On women between 40 and 49, there is no consensus at this time to extend screening at this age.

Box 2. Screening for breast cancer mammography in the general population ANAES, the Guidelines Department, March 1999
Routine screening is recommended in the age group 50-69
In the general population, the benefit of breast cancer screening in terms of avoided mortality is demonstrated in the age group 50-69 years. In this age, routine screening is recommended.
In the age group 70-74 years, breast cancer incidence is high, but data on its mass screening are rare. Given the difficulties of large-scale organization, the extension of screening this age seems premature at present in France. By cons, it is logical to recommend further screening between 70 and 74 years for women previously included in the screening program between 50 and 69 years. In the age group 40-49 years, the benefit of routine screening in terms of mortality avoided is low and appears after at least ten years of regular mammographic follow-up and realized under optimal conditions. The risks of screening is invalid, in particular the risk of false positives that result in the completion of additional tests to confirm the absence of cancer, particularly sources of unnecessary anxiety and psychological trauma. Therefore, the implementation of routine screening in this age group is not currently recommended. In addition, it is essential to first demonstrate the effectiveness of mass screening in France in women aged 50 to 69, before extending to younger women in whom the benefit is currently uncertain and controversial.
The realization of a mammogram every two years is recommended
The time between mammograms should always be less than three years. When mammography is repeated every three years, cancers “interval” discovered during the third year are much more numerous. The realization of a mammography every two years is recommended.
The completion of two mammographic views is recommended at least during the first two waves of screening
If some tests or programs were able to show their effectiveness with a single mammography incidence (external oblique) in optimal conditions of realization, two mammographic views (external oblique and craniocaudal), at least in the first wave, improve the performance of screening. The current implementation conditions of routine screening in France led to propose the implementation of two mammographic views (external oblique and craniocaudal) at least in the first two waves of screening. In all cases, the conditions for achieving the shots must be optimal.
Groups of women xclude the screening program
Breast cancer routine screening is not recommended for women with breast cancer known and regularly monitored for this, or in those who have a familial predisposition to breast cancer, for which there are specific recommendations. However, the orderly routine screening requires that all women of the chosen age range are invited to screening. The possible exclusion of a woman of routine screening should be decided in close cooperation with his doctor.

Box 3. Opportunity to expand breast cancer screening program for women aged 40-49 years.
Technology Assessment Department, Economic Evaluation, March 2004
The updating of data in the literature does not provide data from a sufficient level of evidence to challenge the recommendations of the ANAES 1999. The extension of the French screening program for women aged 40-49 years can not be considered without its efficiency and profitability have been proven to the population of women aged 50 to 74 years. These findings may be reviewed after the publication of the results of English multicenter randomized trial studying the efficacy of screening for breast cancer with annual mammography in women aged 40-41 years at baseline.