3 Technology description
3.4 Description of the surveillance process
A flow chart showing the different stages in a surveillance programme is shown in Figure 3.1.
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Figure 3.1 Surveillance flow chart
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Women who have been identified as being at elevated risk of breast cancer are invited to participate in a surveillance programme that may consist of
mammography, MRI or a combination of both at certain intervals. The overall clinical outcomes of a surveillance programme will depend on the choice of population (age range and risk profile), imaging modality and testing interval. Different combinations of risk groups, age ranges, imaging modalities and surveillance intervals that could be used in a prospective surveillance programme are shown in Figure 3.2.
Figure 3.2 Components of a surveillance programme and list of potential options within each component
A summary of the role of MRI and mammography in clinical guideline
recommendations and surveillance programmes that are currently in place in a number of other countries is provided in Table 3.1.
• MRI
• Mammography
• MRI and mammography
• 6 months
• 1 year
• 2 years
• 25-49
• 30-49
• 35-49
• 40-49
• High risk
• Moderate risk
Population
Risk Profile Age Range
Imaging Tests Surveillance
Interval
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Table 3.1 International surveillance programmes and clinical guideline recommendations
BRCA1, BRCA2, or not tested, but equivalent
Ontario(51) Family history or
genetic mutation 30 - 69 Yes Yes 1 year N/A Alberta(52) Strong family history
or genetic mutation
DoHWA(58) 1/8 > Lifetime risk <
1/4 40+ No Yes 1 year ACS(56) Hadden(59) 1/4 > Lifetime risk <
1/2 40+ Yes Yes 1 year
ACS(56) Family history or genetic mutation Key: NHSBSP – National Health Service Breast Screening Service; DoHWA – Department of Health, Western Australia; NCCN – National Comprehensive Cancer Network, USA; ACS – American Cancer Society; ESMO – European Society for Medical Oncology; NHCTF – National Hereditary Cancer Task Group; NICE – National Institute for Health and Care Excellence; CCO – Cancer Care Ontario.
* Requirement for MRI to be reviewed annually on basis of background density.
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The evidence underpinning these surveillance recommendations is noted to be limited in a number of these guidelines with recommendations based on non-randomised screening trials and observational studies or expert consensus opinion.
Most surveillance programmes limit use of mammography to those aged 30 years and older because of an unfavourable risk-benefit profile in younger women. The use of MRI is discussed as an adjunct to mammography to address the potential
limitations of mammography surveillance in younger women (reduced test sensitivity in dense breasts and exposure to ionising radiation) with none of these guidelines addressing the potential use of MRI as a sole surveillance strategy. The UK
guidelines have been undergoing a process of review over the last three years and were put out to public consultation in January 2013.(66) The main revisions have been to state that, other than for research purposes, women aged less than 40 at elevated risk of developing breast cancer should not have any mammography surveillance and only digital mammography should be used for those aged 40 to 49. Furthermore, for women with TP53 mutations, no mammography surveillance should be used before the age of 50.
The age ranges and surveillance intervals in this HTA were chosen based on the review of research evidence, a review of surveillance programmes elsewhere and through discussion with the Expert Advisory Group. All possible permutations were not assessed as some potential combinations of the above parameters did not represent feasible surveillance strategies due to clinical, logistical or resource requirements. For instance a biennial programme that alternates between MRI and mammography in the 45-49 year age group would not represent a feasible option due to the relatively short period of time between entering and leaving the
programme. Potential surveillance programmes that were included are shown in Table 3.2.
The surveillance scenarios modelled in this evaluation are described in more detail in Chapter 5 (Economic Analysis).
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Table 3.2 Surveillance options: potential imaging modalities, surveillance intervals and age ranges
Surveillance
programme Description Population (age and
risk profile) Biannual alternating
DMX/MRI Women will alternate between receiving a mammogram or MRI scan every six months
Each of these potential surveillance programmes will be modelled
separately for sub-groups within the high-risk
cohort; the high risk; and the moderate risk group within each of the following age bands:
• 25-49 years
• 30-49 years
• 35-49 years
• 40-49 years.
Annual DMX Mammogram every year Annual MRI MRI scan every year Annual DMX+MRI Mammogram and MRI
performed at the same time every year
Annual alternating
DMX/MRI Women will alternate between receiving a mammogram or MRI scan every year
Biennial DMX Mammogram every two years Biennial MRI MRI scan every two years Biennial DMX+MRI Mammogram and MRI scan
performed at the same time every two years
Key: DMX – digital mammography; MRI – magnetic resonance imaging.
Mammography and MRI images are classified according to the Royal College of Radiologists Breast Group (RCRBG) imaging classification system.(67) This system specifies five different categories (1-5) with a prefix indicating which imaging modality was used (MRI for MRI and M for mammography). Table 3.3 provides a description of each of the five categories, along with a summary of how these relate to the American College of Radiology BI-RADS classification system, which was the system used in the studies included in the review of the sensitivity and specificity of mammography and MRI for this HTA.
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Table 3.3 Comparison of BI-RADS and RCRBG imaging classification systems (adapted from Maxwell et al. 2009(67))
Category BI-RADS RCRBG
0 Assessment incomplete.
Need to review prior studies and/or complete additional imaging
-
1 Negative.
Continue routine screening Normal/no significant abnormality.
There is no significant imaging abnormality
2 Benign finding.
Continue routine screening Benign findings.
The imaging findings are benign.
3 Probably benign finding. (<2% chance of malignancy) Short-term follow-up mammogram at 6 months, then every 6-12 months for 1-2 years
Indeterminate/probably benign findings.
There is a small risk of malignancy.
Further investigation is indicated.* 4 Suspicious abnormality. Perform
biopsy, preferably needle biopsy Findings suspicious of malignancy.
There is a moderate risk of
malignancy. Further investigation is indicated.
5 Highly suspicious of malignancy:
appropriate action should be taken.
Biopsy and treatment, as necessary
Findings highly suspicious of malignancy. There is a high risk of malignancy. Further investigation is indicated.
6 Known biopsy-proven malignancy, treatment pending. Assure that treatment is completed
-
Key: BI-RADS – American College of Radiology Breast Imaging Reporting and Data System; RCRBG – Royal College of Radiologists Breast Group.
* No short interval follow-up recommended in RCBRBG system.
Women with negative screens remain in the surveillance programme and undergo repeat imaging at the next surveillance interval. Women who are symptomatic are referred directly to a symptomatic breast clinic for triple assessment.≠ Asymptomatic women with an abnormal test result are recalled to the radiological assessment clinic.
The aim of this assessment is to establish a diagnosis of malignant or benign pathology so that further treatment can be planned or the woman returned to routine surveillance. It is assumed that women within the surveillance programme who present symptomatically between surveillance intervals will also be assessed at the radiological assessment clinic. Clinics are attended by a breast radiologist trained and experienced in breast screening, nursing staff, appropriate radiography staff and supported by clerical staff. The assessment process involves further imaging
≠ An assessment which includes clinical examination, imaging and pathology tests.
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(ultrasound and supplementary mammographic views), as necessary, clinical examination and biopsy for histology where indicated. Image-guided (MR-, ultrasound- and stereotactic-guided) biopsy is used as appropriate. In suspected cases of cancer, ultrasound of the axilla is also performed to determine if there are lymph node abnormalities, with image-guided biopsy of suspicious nodes performed for further assessment as necessary. The results of all assessments that include a biopsy are discussed at the weekly multidisciplinary team meeting (Figure 3.3).
Figure 3.3 Multidisciplinary assessment of positive surveillance test result
If the results of the multidisciplinary assessment indicate that the surveillance test result was a false positive, the patient remains in the surveillance programme and receives another imaging procedure at the next surveillance interval. Patients with a confirmed diagnosis of breast cancer will undergo further tests to determine the stage of their cancer. Appropriate treatment will be provided based on cancer stage and other relevant clinical information. Treatment options include wide local excision, mastectomy, sentinel node biopsy and axillary node dissection, radiotherapy,
hormone therapy and chemotherapy. (See Table 5.2 in Chapter 5, Economic Evaluation.)
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3.5 Key Messages
Unlike mammography, there is no radiation exposure associated with MRI.However, MRI requires the administration of a contrast agent prior to imaging.
The sensitivity of mammography is lower for women with dense breast tissue.Tissue density is less of a factor in MRI surveillance.
Due to the potential for hormonal factors to influence the performance of MRI, diagnostic accuracy may be higher if testing is performed in week two of the menstrual cycle.
It is recommended that surveillance MRI is deferred in pregnancy and lactation as the gadolinium-based contrast agent is contraindicated in pregnancy.
There are a range of age groups, imaging modalities and surveillance intervals that could potentially be employed in a surveillance programme. International practice varies, however, current guidance typically avoids use ofmammography in those aged less than 30 years and limits use of surveillance MRI to that of an adjunct to mammography.
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