The controversy surrounding high risk screening is now limited. MRI for screening has not been very popular in women with average risk due to concerns about the low specificity leading to additional biopsies, time and cost of technology. It is also evident that mammography with its lower sensitivity is limited in women with dense breasts. Mammography is also accused of picking up the more indolent cancers.
Breast MRI uses intravenous contrast administration Gadolinium but not limited by breast density and preferentially detects the higher-grade lesions. Christiane Kuhls's study published recently did not report any interval cancers, and the negative predictive value of MRI is high, thereby allowing a longer screening interval.
The abbreviated protocol for MRI screening developed by Christiane Kuhl, promises to reduce the time taken for the study and interpretation, and the cost with a high negative predictive value in breast cancer screening. DCIS on a mammogram is usually identified by the presence of microcalcifications. The tumour within the terminal ductal units and the ducts outgrows its blood supply, undergoes necrosis and calcifies. MRI does not pick up these calcifications.
However, the non-mass enhancement that is seen in DCIS id probably because the gadolinium permeating into the ducts through the leaky basement due to protease activity produced by tumour cells. Thus MRI might actually detect the more clinically relevant high grade lesions. The kinetic are variable and contribute less to the diagnosis of DCIS. The use of breast MRI in the preoperative setting for women with a recent breast cancer diagnosis is controversial, with wide variations in practice.
Preoperative MRI is likely to detect multifocal and multicentric lesions and evaluate the contralateral breast, especially in lobular cancers and in dense breast. A systematic review that included 3 RCT's and 16 comparative studies were included in the meta-analysis was performed to identify studies reporting quantitative data on pre-operative MRI and surgical outcomes.
MRI is also said to define the size and extent of the tumour better for planning surgery. While this is expected to reduce re-excision rates along with a decrease in the local recurrence rates and overall survival rates, this has actually not borne out in reality. It however leads to increase in additional biopsies, patient anxiety, cost, delay the onset of treatment and possibly increase in mastectomy rates.
Addition of MRI to routine clinical care in patients with non-palpable breast cancer was paradoxically associated with an increased re-excision rate. Therefore they recommended that breast MRI should not be used routinely for preoperative work-up of patients with non-palpable breast cancers.
The adequacy of the margins has been discussed extensively with wide variation in practice. The SSO-ASTRO consensus guidelines in made clear recommendations on the adequacy of margins which for an invasive cancer is no ink on tumour and 2 mm for ductal carcinoma in situ.
Pre-operative MRI is probably not warranted routinely in patients who can be adequately analyzed by mammography and ultrasound examination. It certainly may be valuable in women with dense breasts and in patients with lobular cancer. Neoadjuvant chemotherapy has been used successfully to downstage tumours to bring them within the scope of surgery.
Neoadjuvant chemotherapy is now increasingly used to conserve the breast in large operable lesions. Breast MRI provides the best imaging correlation with pathology and many studies have shown the MRI is superior to clinical assessment, mammogram and ultrasound. In most centres, a clip is placed after a core biopsy in the centre of the tumour with additional clips to mark the extent of the lesion.
Non responders are identified early on MRI using a combination of size and kinetic changes with interpretation facilitated by CAD systems offering volumetric analysis and parametric colour mapping.
Contrast enhancement on MRI correlates with viable tumour. However, the estimation of tumour size by measuring the extent of enhancement may not be accurate with possible underestimation and over estimation. Tumour necrosis may lead to reparative changes, and result in granulation tissue, which may also enhance with contrast leading to overestimation.
Chemotherapeutic agents like taxanes may have anti angiogenic action without corresponding tumour necrosis resulting in lack of enhancement and thereby over estimating the response to NACT. Scattered focal areas of enhancement Swiss cheese like appearance may have scattered residual tumour nests across the original extent of the tumour necessitating a mastectomy.
MRI is superior to x-ray mammogram in high-risk breast cancer screening. In women with low to average risk of breast cancer, the role of MRI remains controversial. The use of pre-operative MRI continues to be controversial with wide variations in practice. In a neo-adjuvant setting, MRI breast is useful to identify the non-responders early. In those who respond to chemotherapy, it is helpful in planning conservation where feasible.
National Center for Biotechnology Information , U. South Asian J Cancer. Selvi Radhakrishna , S. Agarwal , 1 Purvish M. Parikh , 2 K. Saxena , 5 Madhavi Chandra , 5 and Seema Sud 7. Purvish M. Author information Copyright and License information Disclaimer. Correspondence to: Dr. Selvi Radhakrishna, E-mail: moc. Moreover, MRI screening is important not only for women at high risk, but also for those at moderately increased risk.
Women underwent screening rounds consisting of annual MRI, annual digital mammography and half-annual screening ultrasound examinations.
These results confirm once more that MRI is essential for surveillance not only of women at high risk, but also for women at moderately increased risk of breast cancer. Moreover, the results contradict current guidelines according to which mammography is considered indispensable for breast cancer screening.
One aim of the EVA trial was to question this concept and to ask whether it is still appropriate to require that MRI should only be used in addition to mammography.
The results speak for themselves: If an MRI is available, then the added value of mammography is literally negligible. Researchers conclude that MRI is necessary as well as sufficient for screening young women at elevated risk of breast cancer. Since mammography appears to be unnecessary in women undergoing MRI, its use is no longer justifiable, and current guidelines should be revised to reflect this. Current guidelines for women at high familial risk of breast cancer recommend annual MRI with or without ultrasound and annual MRI starting at age In the past, MRI was used strictly in addition to mammography only.
The allegedly high rate of "false positive" diagnoses and the allegedly insufficient sensitivity for DCIS were the main reason to discourage its use as a stand-alone method for breast cancer screening. Materials provided by University of Bonn. Note: Content may be edited for style and length. Science News. Current guidelines questionable Current guidelines for women at high familial risk of breast cancer recommend annual MRI with or without ultrasound and annual MRI starting at age Story Source: Materials provided by University of Bonn.
Journal Reference : Kuhl et al. ScienceDaily, 8 March
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